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CR 5500, REPLACEMENT OF BRIDGE 8130 OVER SAN JUAN RIVERPhase IA/B Detailed Evaluation of Alternatives

Table of Contents1. Executive Summary ............................................................................................................................................ 1

2. Introduction ....................................................................................................................................................... 6

3. Background and Study Process ........................................................................................................................... 6

3.1 Project Description ........................................................................................................................................... 6

3.2 Project Location and Limits ............................................................................................................................... 6

3.3 Project Context / Consistency with Regional Plans ............................................................................................ 6

3.4 NMDOT Location Study Procedures and Alternatives Evaluated ........................................................................ 6

4. Existing Conditions.............................................................................................................................................. 7

4.1 Existing Traffic Conditions ................................................................................................................................. 7

4.1.1 Crash History Review ..................................................................................................................................... 8

Highest Contributing Factor: ................................................................................................................................... 9

Crash Severity: ........................................................................................................................................................ 9

Crash Rate: ............................................................................................................................................................. 9

4.1.2 Crash Analysis Findings .................................................................................................................................. 9

4.1.3 Future Traffic Forecasts – Projected Traffic Volumes .................................................................................... 10

4.2 Existing Roadway Conditions ........................................................................................................................... 11

4.3 Existing Structure Conditions .......................................................................................................................... 11

Load Rating Methodology ..................................................................................................................................... 11

4.4 Existing Environmental Conditions .................................................................................................................. 16

4.4.1 Natural Resources ........................................................................................................................................ 16

4.4.1.1 Soils .......................................................................................................................................................... 16

4.4.1.2 Vegetation ................................................................................................................................................ 16

4.4.1.3 Wildlife, Threatened and Endangered Species ........................................................................................... 16

4.4.1.4 Threatened, Endangered, and Sensitive Species ........................................................................................ 16

4.4.1.5 Wetlands and Water Resources ................................................................................................................ 17

4.4.1.6 Historic and Cultural Resources ................................................................................................................. 17

4.4.2 CR 5500 Bridge Reconstruction .................................................................................................................... 17

4.5 Social and Economic Resources ....................................................................................................................... 17

4.5.1 Neighborhood and Community Impacts ....................................................................................................... 17

4.5.2 Demographics and Environmental Justice .................................................................................................... 17

4.6 Transportation Planning .................................................................................................................................. 17

4.7 Other Social, Economic and Environmental Considerations .............................................................................17

4.7.1 Visual Resources ..........................................................................................................................................17

4.7.2 Hazardous Materials ....................................................................................................................................17

4.7.3 Air Quality ....................................................................................................................................................17

4.7.4 Noise ............................................................................................................................................................18

5. Project Purpose and Need .................................................................................................................................18

5.1 Physical Deficiencies .......................................................................................................................................18

5.2 Roadway Capacity ...........................................................................................................................................18

5.3 Safety ..............................................................................................................................................................18

5.4 Multi-Modal System Connectivity....................................................................................................................18

5.5 Project Purpose ...............................................................................................................................................19

6. Alternatives Considered ....................................................................................................................................19

6.1 No-Build Alternative ........................................................................................................................................19

6.2 Alternative 1 – New Alignment Approximately 20’ West of Existing Alignment ................................................19

6.3 Alternative 2 – New Alignment Approximately 8’ West of Existing Alignment ..................................................19

6.4 Alternative 3 – Existing Alignment ...................................................................................................................19

7. Design Considerations .......................................................................................................................................20

7.1 Traffic Analysis Methods .................................................................................................................................20

7.2 Accessibility ....................................................................................................................................................21

7.3 Structures .......................................................................................................................................................21

7.4 Drainage .........................................................................................................................................................21

7.5 Local Drainage Improvements .........................................................................................................................21

7.6 Constructability of Build Alternatives ..............................................................................................................21

7.7 Roadway Alternatives .....................................................................................................................................22

7.8 Bridge Structure Alternatives ..........................................................................................................................22

7.9 Right-of-Way Requirements ............................................................................................................................22

7.10 Utility Impacts ...............................................................................................................................................22

7.11 Construction Costs ........................................................................................................................................23

8. Environmental Analysis of Alternatives .............................................................................................................23

8.1 Alternative 1 – 20’ Alignment Shift ..................................................................................................................24

8.2 Alternative 2 – 8’ Alignment Shift ....................................................................................................................24

8.3 Alternative 3 – Existing Alignment ...................................................................................................................24

8.4 No Build ..........................................................................................................................................................24


8.5 Summary ........................................................................................................................................................ 24

9. Evaluation Criteria ............................................................................................................................................ 24

10. Conclusions and Recommendations .............................................................................................................. 28

10.1 Preferred Alternative .................................................................................................................................... 28

Appendix A - Conceptual Design Drawings

Appendix B - Environmental Services Report by Ecosphere

Appendix C - BR 8130 Latest Inspection Report

Appendix D - 2015 New Mexico Crash Highlights Report

Appendix E - Hydrology Report

Appendix F - Farmington Metropolitan Planning Organization Exhibits

Appendix G - Engineer's Cost Estimate


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1. Executive SummaryProject Background and Limits

A Combined Location Study and Detailed Evaluation of Alternatives for the replacement of Bridge 8130 onCounty Road (CR) 5500 over the San Juan River has been developed and is summarized herein. Theproject is located in San Juan County, New Mexico, between the City of Farmington and the City ofBloomfield in an unincorporated area known as Lee Acres. Lee Acres is primarily a suburban residentialcommunity.

The bridge is located on CR 5500 at an elevation of approximately 5,400 feet, crossing the San Juan River.The bridge is approaching 50 years old and does not meet current design or load carrying standards.Inspection and evaluation of the bridge by New Mexico Department of Transportation (NMDOT) has notedthe continued deterioration of the six span bridge. A further study of the bridge was conducted byGEOMAT, Inc. in February of 2015 that load rated the bridge and developed the requirement to post amaximum allowable weight limit of vehicles using the bridge. Bridge 8130 does not accommodatebicyclists, pedestrian or equestrian users with safe travel; in fact, there are no facilities at all.

Bridge 8130 is located on CR 5500 between the intersection with US 64 on the north and US 550 on theeast. The bridge is located approximately nine tenths (0.9) of a mile south of the intersection of CR 5500with US 64 and six and a half (6.5) miles west of the intersection of CR 5500 with US 550. The designlimits for the bridge replacement and roadway are defined as approximately one half mile north and southof the existing bridge, to account for a shift in horizontal alignment.

Purpose and Need`

The need for this project is based on evaluations of existing engineering, operational, and environmentalconditions and are summarized as follows: eliminate the physical deficiencies in the existing bridge tosatisfy current design guidance and standards for operations, address safety and improve capacity , andprovide facilities for bicycle and pedestrian users.

The purpose of the proposed project is therefore to do the following:

· Remove the physical deficiencies by replacing the existing bridge with a new bridge of sufficientcarrying capacity for highway vehicles and loads;

· Increase the width of the new bridge to accommodate bicyclists, pedestrian and equestrian users,as well as motor vehicle traffic; and

· Address safety discrepancies with a new bridge meeting AASHTO engineering design criteria .

Analysis Methodology

In order to meet present and future traffic demands for CR 5500, traffic forecasts were developed inconjunction with Farmington Metropolitan Planning Organization (FMPO). The design year (2040) trafficforecasts were developed based on the FMPO 2040 Metropolitan Transportation Plan and the plannedtransportation network and socio-economic data adopted by FMPO. The Average Weekday TrafficVolumes forecast for 2040 for the build condition are significant and include 10,000 vehicles per daytraveling over the bridge (northbound and southbound).

The Highway Capacity Manual has been used to analyze and evaluate the level of performance of CR5500.

Regarding the roadway alignment, alternative alignments were developed for evaluation and comparison oftheir characteristics and performance with respect to meeting current roadway design criteria while alsominimizing impacts to adjacent properties, buildings and wetlands. All alternatives were developed basedon the assumption that right of way acquisition would be limited and no acquisition of buildings or relocationof residents would be considered. With adjacent properties developed and occupied, particularly on thenorth side of the river, opportunities for alignment shifts away from the existing roadway and bridge werevery limited. All alternatives were thus designed with phased construction planned.

Bridge Load Rating and Safety Concerns

A load rating of the bridge was performed on BR 8130 using AASHTOWare’s BrR load rating program. Theprogram simulates a truck crossing over the bridge and produces a rating of the bridge depending on howwell the bridge handles the loads caused by the truck. BR 8130 has previously been load rated by others.The previous rating showed that the bridge was insufficient to carry the standard load rating vehicleweighing 36 tons and was in need of a safe posting load of 22 tons.

AECOM has performed a new load rating to verify the 22 ton weight limit. A field visit was made and thenecessary dimensions taken in order to create an accurate and realistic model of the bridge. Once themodel was created, the results indicate the 22 ton weight limit is correct for an as-built load rating.However, there is minor to severe deterioration in all of the girders which affects the load-bearing capacityof each girder. Therefore, deterioration was applied to the girders and the load rating results indicated thatthe safe posting load should be 13 tons not the 22 ton limit which is currently posted.

Other noted deficiencies at the bridge include limited sight distance, limited width of bridge for passingoncoming vehicles, no crossing or refuge area for bicyclists or pedestrians, inadequate bridge railing,insufficient clearance between girders and the water surface elevation of 50-year and 100-year flow events,and deterioration of materials.

Photos on the following pages illustrate the existing conditions and deterioration of Bridge 8130.


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Damaged bridge railing post. Water surface elevation close to hitting bottom of pier cap.


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Deficiencies at joint include raveling and cracking of bridge deck, and the method of connection of thegirder bearing on pier cap

Area of San Juan River flood plain


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Alternatives Evaluated

The following alternatives were analyzed and evaluated in this Detailed Evaluation of Alternatives process:

· Alternative 1 – design new roadway alignment 20 feet west of existing centerline. Construct aportion of the new bridge (31’-6”) to accommodate 2 – 11 foot lanes and minimal shoulders andoffsets, while maintaining traffic on existing bridge. Demolish all of existing bridge then completeconstruction of new bridge.

· Alternative 2 – design new roadway 8’ feetwest of existing roadway. Construct 1 – 11 foot lane withminimal shoulder (18’-6”) of the new bridge then demolish 8’-9 ¼” of existing bridge. One lane oftraffic would be maintained on the new bridge and one lane on the existing bridge. Continue to addonto new bridge providing 2 – 11 foot lanes for traffic on the new bridge. Demolish existing bridgeand complete new bridge.

· Alternative 3 – use the existing alignment. Part of the existing bridge would be demolished whileone (1) lane of one-way traffic would be maintained and a portion of the new bridge is constructednext to the existing bridge. During construction a temporary signal or flaggers would be required24/7 for the shared lane. A minimal lane width of 11 feet with two (2) feet for temporary concretewall barrier would be required, reducing the initial demolition to 11 feet.

· The No-Build Alternative – assumes there will be no bridge replacement or reconstruction of theexisting bridge or roadway, and only typical maintenance activities would be performed.

In addition to the traffic analysis, each alternative was designed to a conceptual level. This conceptualdesign resulted in evaluation data regarding the bridge, retaining walls if needed, roadway construction,drainage facilities, constructability, area of land impacts, utility impacts, right of way requirements andcosts. Quantities for each alternative were calculated and conceptual construction cost estimates weredeveloped for each alternative. The primary purpose of the estimates at this time is for comparativeevaluation of alternatives. The total project cost estimates for the alternatives as evaluated range from$5,302,000 to $4,482,000. The estimated project cost for the Preferred Alternative is $4,482,000.

Alternative Evaluation and Ranking

The alternatives were evaluated to consider the cost of construction and in addition, the impacts to theneighborhood and community during construction. A list of environmental, neighborhood and communityimpacts considered include:

· Distance and length of time to travel detour routes;· Wait time for shared use lane if project is reduced to a single lane;· Critical link / access to communities;· Air and noise impacts during construction (total project construction time);· Cultural events and holidays;· Demographics and environmental justice; and· Critical times to wildlife (breeding and nesting) during construction.

None of the alternatives is expected to have disproportionate adverse impacts on minority, low income, orother special status populations.

Alternatives considered the span length, number of foundations in the river, and cost for construction ofeach phase.

Table 1. Alternative Ranking

Alternative Cost RankingAlternative 1 Concrete – 20’ Offset $4,482,000 1Alternative 2 Concrete – 8’ Offset $4,482,000 2

Alternative 3 Concrete – Existing Alignment $4,568,000 3Alternative 1 Steel – 20’ Offset $5,218,000 4

Alternative 2 – 8’ Offset $5,218,000 5Alternative 3 Steel – Existing Alignment $5,302,000 6

Preferred Alternative

The preferred alternative for the replacement of Bridge 8130 over the San Juan River is to construct a newbridge with the 20’ – 4 ¾” shift in alignment to the west. Concrete precast girders would be used since theyare less expensive than steel girders.

Agency Coordination and Public Involvement

Development of the project concepts and this study has involved participation of the followinggovernmental agencies in addition to the sponsoring agency, San Juan County (SJC) – the FarmingtonMetropolitan Planning Organization (FMPO).

A public information meeting for the Bridge 8130 Replacement project will be held during the future PhaseIC, inviting public agencies, stakeholders and the community.

Environmental Investigations and Recommendations

A draft biological assessment and pre-field records review and reconnaissance cultural resource surveyhave been conducted for the project. (See Appendix B for a copy of the report prepared by EcosphereEnvironmental Services, Inc.) Other detailed environmental investigations and surveys of the project sitewill be conducted during Phase IC for items identified during the preliminary investigation and survey. Thestudy will include a Clean Water Act Section 404 Permit.

A hazardous material survey will be performed that will include investigation for the use of asbestos andlead based paint related to existing utilities and the existing bridge.

Wetlands have been identified on the west side of the site. The wetlands may not be affected depending onthe alignment alternative selected. A Clean Water Act Section 404 Nationwide Permit will likely be requiredto authorize the crossing of the San Juan River.


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Figure 3.1 - Vicinity Map

2. Introduction

Figure 3.2 - CR 5500, Bridge 8130 Project Limits

The following document consists of a detailed evaluation of alternative concepts for the replacement ofBridge 8130 over the San Juan River on CR 5500. This evaluation and conclusion has been progressedbased upon interim meetings with San Juan County (SJC) during the development of alternatives. Four (4)alternatives for the replacement of Bridge 8130 on CR 5500 were initially proposed and evaluated as partof the Phase IA/IB process, in addition to the No-Build alternative. Determination was made for three (3) ofthe alternatives to be carried forward into the more detailed analysis represented in the Phase I-B process.This Detailed Evaluation of Alternatives documents the in-depth studies of three (3) concepts for newalignments for bridge replacement. The alternative that was discarded as part of the interim meetings isalso described and the reasons for discarding are outlined. Along with the three (3) alternatives progressedin the Phase 1-B process, the No-Build alternative was also evaluated. .

3. Background and Study Process3.1 Project Description

The intent of the project is to develop and analyze viable bridge replacement alternatives that present SanJuan County staff with options for bridge replacement that address necessary project funding and identify

any other important project issues that would affect project programming and subsequent development.This project has been identified as one of the priority transportation projects within San Juan County.

3.2 Project Location and LimitsBridge 8130 is located on CR 5500 in San Juan County. It is located east of Farmington and west ofBloomfield. Refer to Figure 3.1 for a location map of the project.

The study limits for this Phase IA/IB Detailed Evaluation of Alternatives consist of CR 5500 from CR 5476to CR 5510, a distance of approximately 3,600 feet as shown in Figure 3.2.

3.3 Project Context / Consistency with Regional PlansThe project is included in the 2040 Metropolitan Transportation Plan of the Farmington MetropolitanPlanning Organization (FMPO) adopted on September 24, 2015 (See Appendix F).The project is identifiedin Table 5-4, Tier 2 Roadway Projects with an estimated project cost of $3.6 M.

The estimated construction cost for the Preferred Alternative (refer to Section 7.9 and Appendix G of thisreport) is approximately $4.48 million. Other funding sources have not been identified for this bridgereplacement project. Initial project costs have been identified, with contingencies to account for unknownquantities within the confines of the conceptual engineering that has been performed. Development of thefuture design plans and bidding documents is expected to follow the Federal Highway Administration(FHWA) and NMDOT procedures unless local funding is identified for 100% of the cost of the project.

3.4 NMDOT Location Study Procedures and Alternatives EvaluatedThis alignment study was prepared following the 2015 edition of the New Mexico Department ofTransportation (NMDOT) Location Study Procedures. The Location Study Procedures outline a structuredprocess for the preparation of alignment and corridor studies. Alignment studies are generally conducted inthree (3) distinct phases – commonly referred to as Phases IA, IB, and IC. The first two (2) phases serve todevelop, evaluate and refine the range of possible alternatives to address the need for the proposed action.The third (3rd) phase involves the preparation of an environmental document (IC) and subsequentprocessing for the selected alternative in accordance with National Environmental Policy Act (NEPA) andNational Historic Preservation Act (NHPA). Environmental documentation would follow the NEPA process ifFederal funds or lands are involved in the project.

The Initial and Detailed Evaluation of Alternatives Phases, combined for this project as Phase IA/IB, areused to identify alternatives that best address needed operational and safety improvements for the existingcorridor. Alternatives were developed to address project needs, while avoiding or minimizing environmentaland community impacts and addressing issues identified by the major stakeholders. Various alternativeshave been evaluated in the Evaluation of Alternatives, including realignment to the west of the existingcounty road, in order to address the short and long-term needs of the river crossing. For the Phase IA/IBprocess, four (4) alternatives have been evaluated including the no-build option.

Regarding the roadway alignment, alternative alignments were developed for evaluation and comparison oftheir characteristics and performance with respect to meeting current roadway design criteria while alsominimizing impacts to adjacent properties, buildings and wetlands. All alternatives were developed basedon the assumption that right of way acquisition would be limited and no acquisition of buildings or relocationof residents would be considered. With adjacent properties developed and occupied, particularly on thenorth side of the river, opportunities for alignment shifts away from the existing roadway and bridge werevery limited. All alternatives were thus designed with phased construction planned.


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The alignments include:

· Alternative 1 – shifts the alignment approximately 20’ west in order to build two (2) lanes of a newbridge off line while utilizing the existing bridge to maintain traffic during construction;

· Alternative 2 – shift the alignment approximately 8’ west with a location between the existingalignment and Alternative 1’s alignment in order to build one (1) single lane off line while using theexisting bridge and a portion of the new bridge to maintain traffic during construction. Subsequentphases of construction would construct additional width on the new bridge and demolish a similarportion of the existing bridge;

· Alternative 3 – center the new alignment around the centerline of the existing alignment; and· No-Build Alternative – assumes there will be no bridge replacement or reconstruction of the existing

bridge or roadway. The existing river crossing and bridge remain as is.

Use of the existing alignment, closing the road and demolishing the bridge, then constructing a newbridge in its place, was identified as an alternative. Once the existing bridge was demolished, newconstruction would begin in the same location. This alternative was dropped from further considerationdue to the length of the detour route, which was over 30 miles in length; this alternative was not a viableoption to meet the needs of the communities.

Phase IC, the Environmental Documentation phase, will involve the preparation of the environmentaldocumentation and subsequent processing for the selected alternative. The successful completion of theAlignment Study process will allow the selected alternative to be advanced to the Preliminary Designphase, Phase ID.

4. Existing ConditionsThis report addresses the existing transportation system, topography, travel characteristics and trafficconditions, existing roadway alignments and geometry, existing pavement and structure conditions, andaccess. Crash data, existing Right of Way (ROW), drainage, utilities, and existing land use anddevelopment have also been identified in the study and become part of the analysis. Existingenvironmental conditions have also been identified, summarized herein and in the Existing EnvironmentalConditions Report (See Appendix B).

Existing conditions for the project study area consist of a narrow bridge crossing the San Juan River withsimilarly narrow roadway approaches. The topography of the roadway leading to and from the bridge isgenerally flat within the project area. As shown in Figure 4-1, County Road (CR) 5500 begins on the westend with a south/north alignment then turns to the east in an east/west alignment. CR 5500 intersects andbegins at US 64 east of Farmington on the western (northern) end of the alignment and intersects US 550south of Bloomfield on the eastern end of the alignment. The existing road is a two-lane road, with minimalshoulders. The Farmington Metropolitan Planning Organization (FMPO) classifies CR 5500 as a majorcollector. The roadway provides access to Lee Acres, and mobile home parks. The road and bridge havean asphalt concrete paved surface.

Bridge 8130 spanning the San Juan River was constructed in 1971 with no shoulders or sidewalks. Thedistance between guardrails measures 24 feet, face to face. The load limit of the bridge crossing the SanJuan River has been restricted and posted to 22 tons.

The northern limit of the corridor is adjacent to the Sun Ray Park and Casino. Sun Ray Park and Casinoare located at the southwest corner of the intersection of US 64 and CR 5500. Sun Ray Park providesthoroughbred horse racing and is connected to McGee Park, the San Juan County fairgrounds.

CR 5500 also provides access to the Navajo Agricultural Products Industry (NAPI) farms to the southwestof the Project area. NAPI farms include crops of alfalfa, corn (white, yellow and blue), potatoes, pintobeans, wheat and sumac berries. Large rotary irrigation systems provide water for the crops. NAPI farmsalso include livestock such as sheep, cattle and horses, and the highway transport of these products. Dueto the load posting of the bridge the majority of the transport of these products is assumed to movesoutheast to US 550 and then proceed either north or south along US 550 depending upon finaldestination.

4.1 Existing Traffic ConditionsBackground:

CR 5500 forms a connector between US 550 and US 64. The roadway provides access to low densityresidential development, mobile home parks, agricultural and industrial land uses. Community and regionalroad travelers use the roadway as a by-pass, thus eliminating the need to traverse the signalizedintersection at US 550 and US 64 in Bloomfield. The river crossing of CR 5500 is a critical link in theregion’s transportation system.

Figure 4.1.1 Map of CR 5500 and San Juan River

Bridge 3081

CR 5500

US 64

US 550


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Existing Roadway and Traffic Conditions:

Two-way traffic is carried on two (2) 12-foot travel lanes with a paved shoulder of approximately one (1) totwo (2) feet in width along the east and west sides of the north/south road. In close proximity of the northand south ends of the bridge, there is a graveled shoulder of approximately six (6) feet. Pavement widthand shoulders taper to travel lane width only crossing the bridge. The roadway width is reduced to 24 feetfrom face of bridge rail to face of bridge rail on the bridge. No facilities (widened shoulders or sidewalks)have been provided for pedestrians, bicycles or equestrians to cross the bridge.

The speed limit on the eastern portion of CR 5500 is 50 mph then reduces to 35 mph, approximately 1,000feet southeast of the bridge. The posted speed limit is 35 mph crossing the bridge. The transition of thespeed limit from 35 mph to 50 mph is located between CR 5510 and CR 5415.

Detour Route:

CR 5500 forms a connector between US 550 and US 64. If the roadway were closed during construction,then a detour route would be required. There are two (2) detour routes discussed herein.

The first detour route identified was using US 550 and US 64, which is a distance of 30 miles. The seconddetour route was through Navajo Nation’s NAPI area as shown in Figure 4.2. The detour route throughNAPI would require coordination and approval from Navajo Nation and is approximately 25 miles in length.Both detour routes are long and inconvenient to cross the San Juan River during construction. Due to thelength for “out of the way” travel and coordination for use of either detour route, alternatives that wouldrequire detour routes were dismissed.

Figure 4.1.2 Alternate Detour Route through Navajo Nation Agricultural Lands.

4.1.1 Crash History ReviewCrash data was made available for five (5) consecutive years from 2011 through 2015 from the NMDOTPlanning and Safety Division. Seventeen (17) crashes were reported on CR 5500 between CR 5480located north of the bridge to CR 5510 located south of the bridge covering the five (5) consecutive years.The breakdown of the reported crashes and crash types are shown in Table 4.1.1A.

Table 4.1.1A: Reported Crashes and Crash Types by Year

Year CrashType Total

Crash Types 2011 2012 2013 2014 2015

Fixed Object 2 2 1 1 6

Animal 1 1

Other Vehicle 3 2 4 1 10

Yearly Total 5 5 5 1 1 17

Six (6) of the crashes were categorized as fixed object crashes, where the motorist struck a fence orbarricade. One (1) crash with an animal involved a cow. Other types of vehicle crashes accounted for 10crashes, including motorists driving over the centerline (opposite direction), left turn or vehicle enteringfrom a driveway. Ten (10) crashes occurred during daylight, six (6) when it was dark and one (1) crashoccurred at dusk.


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Highest Contributing Factor:Table 4.1.1B: Highest Contributing Factor

ContributingFactor

Year CrashTypeTotal2011 2012 2013 2014 2015 Percent

Alcohol or drugInvolved

0 0 0 0 0 0 0%

Avoid Contact 1 1 5.9%

Drove left ofcenterline

3 1 4 23.5%

Improper Driving 1 2 1 4 23.5%

Excessive Speed 2 1 1 4 23.5%

Failed to YieldROW

1 1 2 11.7%

Missing Data 2 2 11.7%

5 Year Total 5 5 5 1 1 17 100%

Alcohol or drugs were not involved in any of the crashes. Excessive speed was identified in four (4) of thecrashes, 23.5%. One (1) commercial vehicle was involved in the crashes. Five (5) motorists were identifiedas non-local in the crashes while 11 were identified as local motorists. There was missing data for two (2)crashes. The involvement of motorcycles, pedestrians and bicycles was not identified in any of the crashes.A breakdown of the highest contributing factor by year is shown in Table 4.1.1B.

Crash Severity:Table 4.1.1C: Crash Severity-Injury

Year InjuryType Total

Crash Severity-Injury 2011 2012 2013 2014 2015

Fatalities 0 0 0 0 0 0

Incapacitating Injuries 0 0 0 0 0 0

Injury Visible 0 1 0 0 0 1

Injury Non-Visible 2 0 0 0 0 2

Non-Injury 8 9 15 2 2 36

Injuries – 5 Year Total 2 1 0 0 0 3

Of the 17 reported crashes, three (3) were classified as injury crashes. None of the injury crashes wasfatal. There were no incapacitating injury crashes. A breakdown of crash severity by year is shown in Table4.1.1C.

Crash Rate:Crash rates analyzed for CR 5500 based on the five (5) years data provided. The calculated crash rate forthe corridor was compared to the statewide average. That comparison is shown in Table 4.1.1D. Overall,the average crash rate for CR 5500 within the study corridor is approximately 1.2% that of the statewiderate for all highways for the study period.

Table 4.1.1D: State Wide Crash Rate in 2015

CR 5500 Study CorridorCrash Rate

State Wide Crash Rate forAll Highways

(Accidents per 100 MVM) (Accidents per 100 MVM)

182 150

4.1.2 Crash Analysis FindingsCrash data was analyzed over a period of five (5) consecutive years from 2011 to 2015. Of the 17 reportedcrashes, three (3) crashes resulted in injuries. None of the crashes was fatal and there were noincapacitating injury crashes. A breakdown of crash severity by year is shown in Table 4.1.1C.

Alcohol or drugs were not reported as the primary contributing factor in any of the accidents.

One (1) driver reported the accident was a result of accident avoidance.

Four (4) drivers reported driving left of the centerline (on-coming lane) as the primary contributing factorresulting in the accident.

Four (4) drivers reported improper driving (distracted), resulting in an accident.

Excessive speed was reported as the primary contributing factor in four (4) accidents.

Two (2) drivers reported they failed to yield the Right-of-Way (ROW) as the primary contributing factorresulting in an accident.

Two (2) of the accidents were missing data that would have defined the primary contributing factorresulting in an accident.

The large percentage of crashes due to driving left of centerline (23.5%) and avoid contact (5.9%), totaling29.4% combined, may be interpreted as associated with roadway geometrics—particularly the narrowroadway width. In effect, about a third of all crashes in this segment of CR 5500 may be avoidable if theroadway were more forgiving.

The crash rate for the Project segment of CR 5500 is 182 crashes per 100 MVM, greater than thestatewide average for all highways by 21%. This would indicate that this segment of CR 5500 is somewhatmore crash prone than the typical New Mexico state highway.


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4.1.3 Future Traffic Forecasts – Projected Traffic VolumesExisting traffic counts were provided from data obtained from the Farmington Metropolitan PlanningOrganization (FMPO). These volumes are provided in Table 4.1.3 below.

Table 4.1.3. AADT from 2011 to 2015

Traffic Data Year AADT2011 5,2602012 5,39920132014 6,2702015 6,044

Figure 4.1.3A 2040 AADT prepared by Farmington MPO, of CR 5500

The projected volume of traffic on CR 5500 is shown on the diagram above (Figure 4.1.3A) representingthe year 2040. The diagram shows westbound to northbound traffic beginning at the intersection of US 550with a volume of 2,580 (AADT) vehicles. The volume of traffic increases to 5,370 vehicles (AADT)westbound (northbound) as it approaches the intersection of US 64.

The southbound to eastbound projected volume of traffic on CR 5500 is also shown on the diagram above.Traffic volumes at the intersection of US 64 begin with a volume of 5,850 (AADT) which graduallydecreases to a volume of 3,470 (AADT) as it approaches the intersection of US 550.

The diagram in Figure 4.1.3A shows a total AADT of 11,220 just south of the intersection with US 64.There is a forecast AADT of 4730 westbound and 5270 eastbound for a total of 10,000 AADT on CR 5500that crosses the San Juan River.

As shown in Table 4.1.3 above, information was received from the FMPO for the years 2011 through 2015.The current records indicate an existing traffic count of 6,044 AADT for 2015. The projected traffic volumeis forecast by FMPO to increase to 10,000 vehicles per day by the year 2040, on the bridge crossing theSan Juan River. There is forecast to be an increase in traffic volumes of 165% at the bridge crossing from2016 to 2040.

CR 5500 has a functional classification of major collector.

As background information to illustrate the traffic growth related to current or short term vs. futurepopulation distribution, the following two figures are provided with population data within the traffic analysiszones that contribute traffic to CR 5500.

Figure 4.1.3B. Farmington MPO: Traffic Analysis Zone (TAZ) Structure for 2025 Population Distribution

The projected 2025 Population Distribution as shown in Figure 4.1.3B shows a population between 1,486to 3,207 at the southeast quadrant of CR 5500 and US 64. The adjacent center region shown on thenorthern side of CR 5500 of the population diagram shows population that ranges from 801 to 1,485. Theregion shown on the southern side of CR 5500 has a population from 179 to 438. The far eastern portion ofthe CR 5500 corridor at the intersection of US 550 has a minimal population between 0 and 178.

Bridge 8130

CR 5500 US 550

US 64

Bridge 8130


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Figure 4.1.3C. Farmington MPO: Traffic Analysis Zone (TAZ) Structure for 2040 Population Distribution

The projected 2040 Population Distribution, as shown in Figure 4.1.3C, projects a population between1,486 to 3,722 at the southeast quadrant of CR 5500 and US 64. The adjacent center section shows apopulation of 801 to 1,485, and a range of 1,486 to 3,722 on the eastern edge of the center section. The fareastern portion at the intersection of US 550 is depicted as minimal growth, with a population densitybetween 0 and 178.

4.2 Existing Roadway ConditionsThe existing roadway has a curve at the approach and departure of the bridge. The northern curve has aradius of 875 feet, with an unknown superelevation. The southern curve has a radius of 725 feet, also’ withan unknown superelevation. The speed limit is 35 mph. Assuming a design speed of 40 mph,superelevation rates for the north and south curves whould be 3.2% and 3.4%, respectively in order tomeet AASHTO minimum requirements using AASHTO Table 3-8, Minimum Radii for DesignSuperelevation Rates, Design Speeds, and emax = 4%. Design criteria for the new roadway will include areduced level of maximum superelevation on these curves. CR 5500 has a width of 24’ with no pavedshoulder. Gravel shoulders are provided on either side of the bridge with varying widths.

Existing guardrail lengths appear to be sufficient for existing traffic conditions, however the guardrail heightand end terminals appear to be sub-standard when compared to current design guidelines.

4.3 Existing Structure ConditionsThe existing bridge crossing the San Juan River is in generally poor condition and is functionally obsolete.The bridge was constructed in 1971 and was most recently inspected by NMDOT personnel on May 10,

2016. The details of the bridge condition are shown in Table 4.3.1. The Sufficiency Rating (SR) was 22.5in 2016, on a scale of 0 to 100 with 100 being the highest score denoting like new condition. The loadrating of the bridge is HS 7.7 (Inventory) and HS 15.5 (Operating) based on the Load Factor DesignMethod. This load rating is an “as-built” load rating and does not account for the deterioration seen on thebridge. The condition of the deck was rated as 4 (Poor), the condition of the superstructure was rated as 4(Poor), and the condition of the substructure was rated as 4 (Poor). The bridge has a total curb-to-curbwidth (although there is no curb on the bridge) of 23.95 feet. This allows for 2-11’ – 11 5/8” lanes with noshoulders. This does not allow adequate safe width for pedestrians, bicyclist or equestrian.

Table 4.3.1. Bridge Rating

Description RatingSufficiency Rating (SR) 22.5

Load Rating (LR) HS 7.7 (Inventory)HS 15.5 (Operating)

Deck 4 (Poor)

Superstructure 4 (Poor)

Substructure 4 (Poor)

Width 23.95 feet

The topside of the deck is unobservable due to a chip seal surface being in place. There are transversecracks up to 1 ½” in width and minor raveling throughout the pavement joints in the deck. The deck haspatched areas up to 8’ x 8’ and the surface condition overall is fair. Deck faces at the edge of the bridgecontinue to deteriorate at inlet and outlet and have vertical diagonal and horizontal cracks up to 0.02” wide.Deck faces and edges have spalls at isolated areas, with section loss up to 3” along the entire deck edge.Seventy percent (70%) of underside of the deck has transverse longitudinal and diagonal cracks up to0.02” wide with severe scaling and honeycombing due to rough initial construction. The bottom of the deckhas areas with exposed rebar up to one (1) foot square with section loss related to delamination andefflorescence. The deck material was apparently constructed with round river rock (cobble) and Portlandcement concrete. The lower side of the deck has a rough finish. An asphalt concrete with chip seal wearingsurface was placed on top of the Portland cement concrete deck. Heavy debris buildup was observedagainst the steel columns at mid span.

Load Rating MethodologyA load rating of the bridge was performed on BR 8130 using AASHTOWare’s BrR load rating program. Theprogram simulates a truck crossing over the bridge and produces a rating of the bridge depending on howwell the bridge handles the loads caused by the truck. BR 8130 has previously been load rated and thisrating showed that the bridge was insufficient to carry the standard load rating vehicle weighing 36 tonsand was in need of a safe posting load of 22 tons.

AECOM has performed a new load rating to verify the 22 ton weight limit. A field visit was made and thenecessary girder dimensions were measured on site in order to create an accurate and realistic model of

Bridge 8130

CR 5500

US 64

US 550


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the bridge. Once the model was created, the results indicate the posted load rating should be 21 ton weightlimit is correct for an as-built load rating. However, there is minor to severe deterioration in all of the girderswhich affects the load-bearing capacity of each girder. Therefore, deterioration factors were applied to thegirders and the load rating results indicated that the safe posting load should be 13 tons not the 22 ton limitwhich is currently posted. Therefore, it is recommended that San Juan County remove the present 22 tonposting and replace it with 13 ton posting. (This is further documented with a letter to SJC from AECOMdated June 28, 2017; see Appendix C.)

Transverse crack and patch on bridge deck.

Steel girders have minor to moderate rusting. Fascia girders have heavy rusting and there is corrosion atthe abutments and piers where girders attach. Isolated girders are tilted approximately 5 degrees to theeast. Span 4, girder 3 is out of plane. It was observed that there is packed rust between girders and pilecaps. Span 2, girder 4 at cap 2 has considerable section loss up to 50% at the bottom of the flange.Girders have heavy graffiti markings at the ends and at abutments. It was observed that the girders haveheavy mud and dirt buildup.

Rusting of steel girders and rough under decking.

Painted steel columns and bracing have paint system failure with paint flaking and rusting. Piers 3 and 4 atinlet have moderate debris buildup.


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Debris build up at piers

Timber abutments are weathered with moderate splits, moderate to heavy water and dirt staining andisolated areas of wood rotting at bottom planks. Coating system has failed. Abutments are in overall poorcondition.

High water surface elevation (as of June 14, 2017)

High water surface elevation of spring flows approaches the bottom of the piers. Clearance should becalculated with two (2) feet of freeboard above the 50-year surface elevation. The elevation of the bridgedoes not meet the freeboard requirements.


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Debris build-up at pier with high flows

Debris build up at the piers results in a localized water surface elevation higher than the surroundingchannel.

Bridge deck condition with cracks and raveling of Portland cement concrete

The condition of the bridge deck shows cracking and raveling of the Portland cement concrete.


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W Beam connection with utility on side of bridge.

Bridge rail is 12” W Beam rail on steel posts tied to fascia girders with 4” round pipe that acts as wheelrunner. Railing has areas of minor to moderate traffic damage and sagging. At the west end, isolated postsare bent and not functional as intended. An isolated anchor post is cracked at the east end near theapproach. Railing is substandard.

Bent railing supports

Close inspection of the bridge railing shows bent and damaged supports. Engineering design of bridgerailings is intended to redirect the paths of errant vehicles to keep them on the traveled way.


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Abutment with timber planks

Wing walls are constructed out of 12” timber planks that are dry, weathered with heavy checks anddeterioration at the ends. Steel supports are misaligned and separated from timbers. Timbers have severesection loss at ends.

4.4 Existing Environmental ConditionsThis Environmental section consists of a review of existing environmental conditions. This is intended toidentify sensitive resources that may influence the project. The report is contained in Appendix B

4.4.1 Natural Resources4.4.1.1 Soils

Soils, as shown in Table 4.3, in the area are loamy sands, becoming less sandy and saline toward theriver.

Table 4.4 Soil Types

Map Unit Name Location Parent Material Percent ofProject Area

Lakes, rivers,reservoirs (water)

San Juan River (water) 24.10%

Werlog loam, saline-alkali

Northern riverbank to500 feet north of the river

Mixed alluvium 19.80%

Stumble loamy sand,3 to 8 percent slopes

100 – 635 feet south ofthe river

Eolian deposits derivedfrom sandstone

18.02%

Beebe variant loamysand

Northern 500 feet of theproject limits

Stream alluviumderived from igneousand sedimentary rock

16.00%

Walrees loam Southern riverbank Mixed alluvium 10.20%Turley-Slickspotscomplex, 0 to 3percent slopes

1000 feet south of theriver

Fan alluvium derivedfrom sandstone andshale

1.60%

Beebe loamy sand 635 feet south of theriver

Stream alluviumderived from igneousand sedimentary rock

0.30%

4.4.1.2 VegetationThe project site contains dense riparian vegetation in a narrow linear corridor adjacent to the river with anoccasional Rio Grande cottonwood. However, Russian olive, Siberian elm, and salt cedar dominate thevegetation, all of which are classified as Class C Noxious weeds in New Mexico. Roadsides contain featherfingergrass and cheatgrass as well as occasional small rubber rabbitbrush.

4.4.1.3 Wildlife, Threatened and Endangered SpeciesGunnison’s prairie dog are located within the right-of-way. Burrows are encroaching into the right-of-wayand under the roadway surface north of the bridge along CR 5500. These are part of a large prairie dogtown east of the project area.

Other wildlife observed consisted entirely of birds, including Canada goose, house finch, and Americancrow. Remnants of cliff swallow nests were observed beneath the road surface on the bridge.

The Migratory Bird Treaty Act (MBTA) protects against the taking of migratory birds, their nests, and eggsexcept as permitted. If construction is planned during the bird nesting season (March to August), a nestsurvey should be conducted or nests should be removed prior to construction.

4.4.1.4 Threatened, Endangered, and Sensitive SpeciesTwenty-eight (28) special status species may occur in San Juan County, New Mexico. These speciesinclude federally listed threatened and endangered species and State of New Mexico threatened orendangered species. Most of the project area overlaps with U.S. Fish and Wildlife Service designatedcritical habitat for the yellow-billed cuckoo. Five species have the potential to occur in the project areabased on the presence of suitable/critical habitat: Parish’s alkali grass, American peregrine falcon, baldeagle, spotted bat, and the yellow-billed cuckoo. Riparian vegetation within the Project is not suitable fornesting for the yellow-billed cuckoo. The other species could travel through; forage, or perch nearby, but


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construction activities would cause them to simply avoid the area and would result in no loss of suitablehabitat.

4.4.1.5 Wetlands and Water ResourcesThe San Juan River is the main hydrological feature in the study area. The San Juan River is a moderate,seasonal-flow perennial system with some water diverted to acequias. The section of the river within theproject area is an orphan channel with a loamy substrate. The wetted channel averages 100 feet wide and18 inches deep.

Surface water in the project area includes the San Juan River as well as the margins of several relic oxbowimpoundments at the northern end of the project area. Standing water and vegetation indicate potentialwetlands may be present. Although wetlands are not likely to be impacted by the proposed Projectalternatives, a Clean Water Act Section 404 Nationwide Permit No. 14 will likely be required to authorizethe crossing of the San Juan River.

4.4.1.6 Historic and Cultural ResourcesOn April 26, 2017, Okun Consulting Solutions conducted a pre-field records search of the New MexicoCultural Resources Information System (NMCRIS) database to obtain information on all previouslyconducted surveys and documented archaeological sites located within 1,640 feet of the CR 5500 BridgeProject Area. Current listings of the National Register of Historic Places (NHRP) and New Mexico StateRegister of Cultural Properties were consulted to determine the presence of any registered properties ordistricts in the Project vicinity. Based on these record searches, no previously documented resources arelocated within the Project area.

A 100-percent pedestrian cultural resource survey of the Project area was completed on April 28, 2017.The survey area included the entire CR 5500 right-of-way, extending 1,000 feet north and south of theends of the existing bridge. Bridge 8130 is the only cultural resource discovered during this survey. Noarchaeological sites, isolated occurrences, historic buildings, or other resources were discovered within thesurvey area.

4.4.2 CR 5500 Bridge ReconstructionBridge 8130 was constructed in 1971 to span the San Juan River. It has been in place for 46 years. TheNew Mexico Department of Transportation (NMDOT) requires that resources 45 years of age to bedocumented. Documentation is for planning and to accommodate future projects. The bridge was fullydocumented and evaluated during the survey. The steel girder bridge is 238.2 feet long and 24 feet wide,with six (6) spans. The bridge is a common type, exhibits a relatively short length, and is in poor condition.Based on the scoring system presented in NMDOT’s 2014 Historic Bridges in New Mexico: An UpdatedGuide for Evaluation, Bridge 8130 would not qualify for listing on the NRHP when it becomes 50 years old.If it still exists, it will be recommended as not eligible when it reaches 50 years old.

4.5 Social and Economic Resources4.5.1 Neighborhood and Community Impacts

CR 5500 provides access to low-density residential development, mobile home parks, and industrial landuses along both sides of the roadway. It also provides access to the San Juan County McGee Park horseracing track and Sun Ray Park and Casino, located north of the river on the west side of the highway.

4.5.2 Demographics and Environmental JusticeThe community context of the Project includes civil rights and environmental justice considerations, whichrelate to potential disproportionate adverse impacts on minority, low-income, or other special statuspopulations, and groups with special needs such as the elderly and physically handicapped. Data from theU.S. Census Bureau (2015) were reviewed to characterize economic and demographic information aboutthe Lee Acres Census Defined Place (CDP) in comparison to statewide, San Juan County and City ofFarmington.

The Project area in Lee Acres CDP has a percentage of Native American people that is considerablyhigher than the statewide level but similar to other areas in San Juan County. None of the projectalternatives is expected to have disproportionate adverse impacts on minority, low income, or other specialstatus populations.

4.6 Transportation PlanningThe Metropolitan Transportation Plan (MTP), adopted by the Farmington Metropolitan PlanningOrganization (FMPO) in 2015 and the Farmington MPO Bicycle and Pedestrian Plan (FMPO 2008) are theprimary transportation plans that guide development within the project area. The MTP is the long-rangetransportation plan for the urbanized region of the cities of Aztec, Bloomfield, and Farmington and thesurrounding urbanized area of San Juan County. CR 5500 is identified on the MTP’s Major ThoroughfarePlan as a major collector.

CR 5500 Bridge Project is identified in the MTP as a Tier 2 priority, identifying the replacement of the 6-span bridge, a wider alignment, and the addition of pedestrian facilities. The Farmington MPO Bicycle andPedestrian Plan identifies CR 5500 as an existing bike use route and shows a Proposed Regional Projectbetween US 64 and US 550 on the Proposed Regional Bicycle and Pedestrian Network map.

4.7 Other Social, Economic and Environmental Considerations4.7.1 Visual Resources

The visual landscape of the immediate Project area includes the riparian vegetation along the river and theriver itself. Since the Project is primarily limited to replacing the existing bridge, it is not expected toadversely affect the scenic qualities of the visual landscape.

4.7.2 Hazardous MaterialsVisual inspections of the Project area have not identified past land uses or other activities that would resultin potential soil or groundwater contamination, which could affect the project design. An investigation forasbestos containing materials and lead-based paint will likely be needed for the CR 5500 bridge. Additionalresearch and consultation with the NMDOT Environmental Geology Bureau is needed to determine theneed for further investigations.

4.7.3 Air QualityThe Clean Air Act as Amended establishes National Ambient Air Quality Standards (NAAQS) for seven (7)criteria pollutants, including carbon monoxide, nitrogen dioxide, particulate matter less than 10 microns indiameter (PM10), particulate matter less than 2.5 microns in diameter (PM2.50, ozone, sulfur dioxide, andlead. San Juan County has been defined as an attainment area for all NAAQS criteria pollutants. TheProject is not anticipated to result in localized air quality impacts, exceedance of the NAAQS, or substantialclimate change concerns.


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4.7.4 NoiseNMDOT noise policies and procedures are based on the Federal Highway Administration’s Highway TrafficNoise: Analysis and Abatement Guidance (2010) and are described in the NMDOT Infrastructure DesignDirective IDD-2011-02, Procedures for Abatement of Highway Traffic Noise and Construction Noise. Underthe NMDOT’s policy, a noise analysis is required for a “Type I” or a “TYPE II” project. A Type I Projectinvolves the construction of a highway on a new location or the physical alteration of an existing highway,which significantly changes either the horizontal or the vertical alignment, increases the number of throughtraffic lanes, or modifies the existing typical section. A type II Project involves the construction of noiseabatement measures on an existing highway. The proposed Project is not expected to significantly alter thehorizontal or vertical alignment, or change the number of lanes, or cross section in anyway on CR 5500that would increase community noise; therefore, it does not meet the definition of a Type I Project and nonoise analysis will be performed.

5. Project Purpose and NeedThe existing conditions within the project study area have been described in the previous sections. Thereare many aspects of these conditions that demonstrate the need for improvements and need for thereplacement of Bridge 8130. The following section summarizes those critical conditions that clearly indicateProject Need.

5.1 Physical DeficienciesThe existing corridor, defined for this Detailed Evaluation of Alternatives, includes the project segment ofCR 5500 between US 550 on the east and US 64 on the west. The segment in question exhibits certaincritical physical deficiencies. The most obvious and glaring deficiency is the width of the bridge carrying CR5500 over the San Juan River and the width of the existing roadway. A Policy on Geometric Design ofHighways and streets, (AASHTO) recommends lane widths of 12 feet to provide desirable clearancesbetween commercial vehicles traveling in opposite directions on two-lane, two-way rural. Shoulder widthsof six (6) to eight (8) feet is recommended for low volume highways to provide a minimum clearance of one(1) foot for stopped vehicles to clear the edge of traveled way. Bridge 8130 has lane widths of 12 feet withno shoulders.

The six (6) span bridge results in foundation supports in the river, creating obstacles to collect debris.Debris collecting on the foundation could create a horizontal loading hazard on the foundation.

The bridge in its current configuration is functionally obsolete. It is not safe for use by pedestrians,bicyclists and equestrians due to its width. While the existing guardrail lengths of need appear to besufficient, deficiencies exist in its height and the end sections being used. Current design guidelines requirea height of 31” and the use of TL-2 end terminals unless space is limited, which should not be the case forthis corridor. Also, there is no lateral offset from the edge of existing travel lane to the face of existingguardrail throughout the length of the bridge. Current design guidelines recommend a 2’ lateral offsetwhere possible.

5.2 Roadway CapacityThe AADT volume for 2040 crossing the bridge is 10,000 on the 2-lane roadway. Based on the trafficnumbers and crash data there is no evidence that the existing roadway is congested, and therefore, noadditional lanes for roadway capacity are required. The roadway design for Alternatives 1 and 2 have beendesigned for design speed of 40 mph, with posted speed limit of 35 mph.

The speed at which motorists drive on CR 5500 often exceeds the speed limit, creating unsafe conditions.Table 3-8. Minimum Radii for Design Superelevation Rates, Design Speeds, and emax = 4% Super-elevation tables using 4.0% for urban conditions was used to determine the superelevation rate for thehorizontal curves. The northern curve of Alternative 1 is designed with radius of 1,000’ and superelevationof 3.6%. The southern curve of Alternative 1 is designed with a radius of 833’ and superelevation of 3.8%.Super elevation tables and formulas for Urban conditions are used in an effort to have motorists drive atthe speed limit.

The northern curve of Alternative 2 is designed with a radius of 1,190’ and superelevation of 3.4%. Thesouthern curve of Alternative 2 is designed with a radius of 725’ and superelevation of 4.0%.

5.3 SafetyCrash history has been reviewed for the area adjacent to the bridge. Crash data for the area surroundingthe bridge has been researched and analyzed for the period from 2011 to 2015. The crash data suggeststhere are deficiencies within the roadway such as narrow bridge and/or site distance from horizontal curvesto bridge that contributes to the crashes. The crash history suggests bridge is too narrow and excessivespeed is the primary contributing factor for the accidents.

5.4 Multi-Modal System ConnectivityThe Farmington MPO has included CR 5500 on the long-range master plan to include bicycles as shown inFigure 5.4. There are currently no bicycle or pedestrian paths connected to the bridge or corridor. Theproposed bridge replacement with widening would accommodate bicyclists and pedestrians crossing theSan Juan River and provide future connectivity within the corridor when pedestrian and bicycle paths areconstructed.


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Figure 5.4 Regional Bicycle and Pedestrian Plan, prepared by Farmington MPO

5.5 Project PurposeThe purpose of the project is therefore to address the deficiencies and project needs identified in theprevious section and to replace Bridge 8130 to meet current design and operating standards. The newbridge will be designed with the following criteria:

· LRFD loading;· 2 – 12’-0” driving lanes;· Width to include 2 - 6’-0” shoulders;· Width to include 2 - 5’-0” barrier separated sidewalks;· Bridge design to reduce number of spans, and reduce foundations within river, thereby reducing the

locations for debris to collect;· Designed to pass the 50-year flood event with two (2) feet of free board; and· Designed to pass the 100-year event, with surface elevation below the low cord.

6. Alternatives Considered6.1 No-Build Alternative

The No-Build Alternative is defined as no new construction; the existing bridge would stay in place andcontinue to function as it is currently doing. Load rating analyses as previously described may result in the

posting (with signage) of a lower allowable truck weight limit. Typical County road maintenance wouldoccur as is currently being done.

6.2 Alternative 1 – New Alignment Approximately 20’ West of Existing AlignmentThe following “build” alternatives all reconstruct the new bridge on an alignment that is either directly over(as with Alternative 3) or very close to (offset 8-20 feet) the existing alignment and bridge. In certain casesit would be preferable to build a new bridge on a completely separate and non-overlapping alignment so asto not interfere with existing traffic operations while the new bridge is being constructed. For this project,any greater alignment shifts than have been considered with these alternatives would require more right ofway acquisition, have greater impacts to adjacent properties and wetlands, and project costs wouldincrease. For these reasons, the new alignments have been established as described herein.

Alternative 1 shifts the centerline alignment approximately 20’ to the west of the existing alignment. Withthis shift and location overlap of new bridge with old, construction has to be phased. Thirty-one feet, sixinches (31’-6”) of the new bridge would be constructed in Phase 1 and “offline”, which would not affect theuse of the existing bridge. Two (2) lanes of traffic would be maintained on the existing bridge. Once Phase1 is completed, the two (2) lanes of traffic would be shifted onto the new bridge. The existing bridge wouldthen be demolished at the completion of Phase 1.

Phases 2 and 3 construction would add width onto the new bridge to complete the final recommendedwidth of 52 feet.

The roadway profile would be raised for the design of the new bridge to better accommodate river flowswith adequate freeboard. Phasing would affect the profile of the detour onto the new bridge and wouldrequire temporary concrete barrier separation of the northbound and southbound lanes of traffic.

The typical section of this alternative includes travel lane widths of 12 feet, 6-foot shoulders, and 5-footsidewalks. A metal bridge railing with 18 inch width provides positive separation between travel lanes andthe sidewalk. Total bridge width is 52’-0”. See typical sections in Appendix A.

6.3 Alternative 2 – New Alignment Approximately 8’ West of Existing AlignmentAlternative 2 shifts the centerline alignment to the west approximately 8’ from the existing alignment. Withthis shift and even greater location overlap than with Alternative 1 of new bridge with old, construction hasto be phased. Phase 1 construction would be initiated with a new bridge segment width of 15’ – 4”. OncePhase 1 is completed, southbound traffic only would be shifted to the new bridge. Eight feet – nine and onequarter inches would be demolished on the western side of the existing bridge. Southbound traffic would beon the new bridge and northbound traffic would be on the existing bridge. Phase 2 construction would addseven foot six inches (7’ – 6”) to the eastern side of the new bridge. Once Phase 2 construction iscomplete, the northbound traffic would also be shifted to the new bridge. Demolition of the existing bridgewould be completed in Phase 2.

Phase 3 construction would add 24’ – 6” to the east on the new bridge, completing the width to 52’ – 0”.

As with Alternative 1, the roadway profile would be raised for the new bridge. Temporary concrete barrierwould be required for the separation between northbound and southbound traffic to account for the gradingdifference in elevation of the roadway surfaces.

6.4 Alternative 3 – Existing AlignmentAlternative 3 uses the existing roadway alignment. This alternative keeps the new bridge centered on theexisting alignment to minimize the impacts to the adjacent properties, right-of-way, utilities and wetlands.

Bridge 8130

CR 5500


20

For this alternative, one-lane two-way traffic would have to be implemented for a section of roadway tofacilitate demolition of old bridge / construction of new bridge while utilizing 12’ width of old bridge for traffic.This could be accomplished by providing lane closure tapers to indicate closure of a portion of the existingroadway approaching the 12’ available single lane crossing. The purpose of this taper is to control traffic bygiving an appearance of restricted movement and thereby alert drivers of potential head-on conflicts.Temporary traffic signals or flaggers would be provided to control traffic. The figure below illustrates atypical one-lane two-way traffic control. The duration of this traffic control set-up is directly dependent onthe bridge construction schedule and may take several months. It may be beneficial to develop theconstruction schedule by reviewing seasonal traffic patterns such that the bridge construction activitiesrequiring one lane, two way traffic are implemented to affect the lowest seasonal traffic volumes if possible,while also considering bridge pier construction in the river during low flow seasons. Furthermore,Accelerated Bridge Construction (ABC) methods may be adopted to accelerate the schedule in order toreduce impacts to traffic.

Advantages of use of Temporary Traffic Signals:

1. Traffic signals communicate more directly with motorists than flaggers do: red means “stop” andgreen means “go.” Drivers tend to have a clearer understanding of and greater familiarity with trafficsignals,

2. Proper timing intervals can be setup,3. An option is available to use traffic presence detection to detect approaching vehicles and automate

timing,4. Meets MUTCD requirements, and5. Is likely less costly considering the long duration of need.

Disadvantages for use of Temporary Traffic Signals:

1. Approach sight distance may be limited considering the curvilinear roadway alignment (this will requirefurther investigation during the design phase),

2. Motorists delay time may become excessive, and

3. Unable to control high speeds through the work zone.

Figure 6.4A Traffic control for 2-way, 1-lane traffic.

Figure 6.4B Temporary signal used for traffic control of 2-way, 1-lane traffic.

7. Design Considerations7.1 Traffic Analysis Methods

AADT volumes forecasts for 2040 crossing the bridge is 10,000 vehicles per day (vpd).

The Highway Capacity Manual (TRB, 2010) includes service volume tables to provide guidance onmaximum traffic volume for a facility operating with a specific LOS. Table 7.1 exhibits the maximum dailyvolume that can be accommodated by a two-lane highway at a given LOS. Values presented in this tableare a function of the planning analysis hour factor, K (ratio of traffic volume in the study hour to AADT) andthe directional distribution factor, D. Values of D=55% and K=10% were assumed for CR 5500 facility.From Table 1, it can be concluded that a volume of 10,000 vpd (2040 forecast volume crossing the bridge)is well below the maximum daily threshold for most cases for LOS D corresponding to K and D factorsassumed. Even with different assumptions, such as a higher directional split of traffic (D=60%) and a moreconcentrated peak hour (K=12%), the threshold volumes for rolling terrain, LOS D are still 9600 or 10900.Therefore, it can be reasonably concluded that CR 5500 with one lane in each direction should be able toserve 2040 traffic without a need to upgrade to a 4-lane highway facility.


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Table 7.1Table from Highway Capacity Manual prepared by TRB

7.2 AccessibilityThe replacement bridge would include ADA compliant pedestrian and bicycles facilities. Barriers will beconsidered between driving lanes and sidewalks.

The FMPO has listed CR 5500 in their master plans to accommodate a future bicycle trail. The new widebridge will be compatible with this master plan objective and will serve as one of the first components ofplan implementation.

7.3 StructuresThe structural requirements of the bridges discussed in each alternative in Section 6 were determinedusing the same span length, bridge width and superstructure depth. Using this information, structure typeand approximate bridge costs were evaluated with these results presented in Section 9. Retaining walls willalso be required outside the edge of pavement to minimize earthwork within and beyond the existing right-of-way.

7.4 DrainageThe drainage analysis demonstrates compliance with applicable hydrologic and hydraulic criteria for theproposed replacement of Bridge 8130. Key existing condition issues include hydraulic capacity andadequacy of the existing bridge, scour and sedimentation concerns with bridge footings and piers, andstormwater sheet flow traveling across CR 5500 at the ends of the bridge.

From a hydrologic and hydraulic capacity perspective, all of the build alternatives are preferred over the no-build alternative because of the opportunity afforded to address existing hydraulic capacity concerns.Specifically, the foremost of these is raising the profile of the bridge would keep the structure above thedesign flow event and preventing over topping of the bridge.

Hydraulic analysis of all of the proposed alternatives is based on raising the grade for the new bridge by 4-feet along with channel improvements to meet the minimum freeboard requirements for the 50-year and100-year storm flow events.

The San Juan River transports a considerable amount of sediment that could cause large amounts ofsediment deposition at the bridge location thus reducing hydraulic capacity. Maintenance of the channelbanks and overbanks is needed to remove vegetation and sediment that could be deposited within thevicinity of the bridge crossing. Right-of-way or maintenance easements along with an establishedmaintenance schedule is recommended for an appropriate distance upstream and downstream of thebridge to allow for bank maintenance activities.

7.5 Local Drainage ImprovementsLocal drainage improvements will consist of driveway culvert crossings for the driveways impacted by theproposed roadway improvements. The need for and configuration of driveway culverts are expected to bethe same for all three (3) roadway alignment alternatives.

7.6 Constructability of Build AlternativesThe constructability of each of the build alternatives was assessed by examining the probable phasedconstruction sequence necessary to construct the new bridge, and complete the replacement of theexisting bridge while maintaining traffic through the construction zone. The design approach to thealternatives sought to avoid off site detours and minimize the extent of lane shifts and temporary pavementneeded to maintain movements of traffic. In all alternatives except Alternative 3, use of the existingalignment, it is assumed that one (1) lane of traffic will be maintained in each direction during construction.In the Alternative 3, there is a shared use single lane to maintain traffic thru the project site.

Alternative 1 – Approximate 20’ Alignment Shift

The construction phasing of Alternative 1 is straightforward. As the proposed bridge is offset from theexisting bridge to the west, partial widths of the new bridge may be constructed in Phase 1 while trafficcontinues to run on the existing bridge. In Phase 2, traffic is shifted onto the new bridge while the existingbridge is demolished and the remaining width of the new bridge is constructed. Additional pavement will berequired for temporary concrete wall barrier. This alternative provides the best approach to balancing theconstruction of the new bridge off line (at least with the first segment) while maintaining traffic on theexisting bridge.

Alternative 2 – Approximate 8’ Alignment Shift

The construction phasing of Alternative 2 is also straightforward as discussed in Alternative 1 althoughthere is greater overlap of the footprint of the old and new bridges than with Alternative 1. As the proposedbridge is offset from the existing bridge to the west, partial widths of the new bridge may be constructed inPhase 1 while traffic continues to run on the existing bridge. In Phase 2, 1-lane of traffic is shifted onto thenew bridge while 1-lane of traffic continues to use the existing bridge (however, at different grades due tothe higher new bridge profile). A portion of the existing bridge is demolished in order to construct additionalwidth of the new bridge. This phasing may require stabilization of the portion of the existing bridge that ismaintained for traffic. Subsequent phases will continue to add width to the new bridge and demolish the


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existing bridge. Additional pavement will be required to support temporary concrete wall barrier. Thisalternative provides a less desirable approach to balancing construction of the new bridge, only partially offline, with phasing requiring one lane on the new bridge and one lane on the old bridge to maintain traffic.

Alternative 3 – Existing Alignment

The construction phasing of Alternative 3 is not as straightforward as with the previous alternatives.Construction sequencing becomes an issue, as only one (1) lane of traffic would be supported on theexisting bridge. Cure time of the deck slab of the new bridge would require a minimum of one (1) monthbefore traffic can be shifted to the new bridge. Partial widths of the new bridge could then be constructed insubsequent phases. Once Phase 2 has constructed the new bridge to a width to support 2 – 11’ lanes, thetemporary traffic signal would be eliminated and there would be one lane of traffic in each direction. Asnoted in Alternative 2, due to partial demolition of the existing bridge, the portions of the existing bridge tobe maintained may require stabilization. Beginning in Phase 3, traffic would be on the new bridge anddemolition of the existing bridge would be completed. Subsequent phases will continue to add width to thenew bridge until it is completed. Additional pavement will be required for temporary concrete wall barrier.This alternative provides a fairly undesirable approach to balancing construction of the new bridge, whichcompletely overlaps with the old bridge, with phasing requiring an one (1) lane, two-way signal or flaggercontrolled operation for maintaining traffic.

7.7 Roadway AlternativesThe three roadway alignments for this project have been developed with roadway cross-sections that meetthe AASHTO design criteria for the major collector roadway classification. This will result in 2-12 ft. travellanes and 2-6 ft. shoulders. 2-5 ft. sidewalks will be provided to accommodate pedestrians throughout thecorridor. 1’-6” barriers will be placed between the edge of shoulder and sidewalk for the safety ofpedestrian travel throughout the corridor.

The three alternative roadway alignments have been developed to meet the existing roadway alignmentwithin the project limits. The location of the proposed bridge in each alternative is controlling the curvatureof the road for each alignment. For the alternatives shifted to the west the roadway curves have beenflattened to accommodate meeting the existing roadway cross-section at the northern and southern ends ofthe project corridor and meeting the proposed bridge location near the midpoint of the project corridor.This also results in different superelevations of the proposed roadway. The alternatives were reviewed fortwo different design speeds, 35 mph and 40 mph. The superelevation is based on the AASHTO minimumrequirements using AASHTO Table 3-8, Minimum Radii for Design Superelevation Rates, Design Speeds,and emax = 4%. See Table 7.7 for the roadway data.

Table 7.7. Roadway Criteria

Alternative Design Speed Curve Radius (ft.) Superelevation (%)

1

40 North 1000 3.540 South 833 3.735 North 1000 3.035 South 835 3.2

2


3


7.8 Bridge Structure AlternativesThe concept design of the new bridge includes two (2) alternative structure types. The first structure type isconcrete girders, the second type would use steel girders. These two alternative types compareconstruction material costs and adjustments to roadway profiles. The structure depth of the concretegirders and deck is 53 1/2”. The structure depth of the steel girders and deck is 38 1/2". The concretegirder bridge alternative would require that the adjacent roadway be raised a minimum of 4 ft. while thesteel girder alternative would require the adjacent roadway be raised a minimum of 3 ft. Concrete girdersare less expensive than steel girders but would require additional earthwork to raise the adjacent roadwayprofile. See Appendix A for Alternative Typical Sections and Profiles of the bridges.

7.9 Right-of-Way RequirementsThe existing fence lines are visible and have been physically identified from aerial mapping. Digital shapefiles of property ownerships have been provided by the County. This property line data conflicts with themapping data with respect to roadway right of way. According to the shape files, there may be no formallydefined right of way; the roadway may be located within a roadway “prescriptive use” right of way or withinprivate property. A boundary / right of way survey will be required to establish the right-of-way. Based oninformation available at the time of this report, it is clear that all of the alternatives will require additionalright-of-way. Topographic survey and boundary location will be required during design to determine theextents of right-of-way required.

7.10 Utility ImpactsOverhead electrical transmission lines and overhead communication lines are located on the west side ofthe bridge, near the existing western fence line. A natural gas line has been attached to the structure onthe west side of the bridge. There are markers indicating additional utilities exist within the immediatevicinity of the bridge, including water, and communications. The following utilities with contacts areexpected to be present at the Project site.

· Communications – Century Link. Communication lines are attached to the utility poles, belowelectrical supply. Laurence Joe, [email protected] 505-409-8042

· Electricity – Farmington Electric Utility Company. Electrical transmission lines are located on theutility poles to the west side of CR 5500. 505-599-1353


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· Gas / Petroleum – NM Gas Company. A natural gas line is attached to the bridge structure. LeviMoore, [email protected] 505-324-3783

· Water Supply –Lee Acres. Aaron Lee, 505-325-8317, 505-632-2987. Water supply on the northside of the bridge. Water main is located on the east side of the roadway.

· Water Supply – West Hammon Ditch. Sam Purda, 505-632-2987. Water supply on the south side ofthe bridge.

The design of the bridge is expected to include attaching the natural gas line to the west side of the newbridge. This will require an alignment shift from its present buried location.

Alternatives 1 and 2 begin construction of the new bridge to the west of the existing bridge. Once the firstphase is completed, the natural gas line would be relocated to the new bridge.

The relocation of the natural gas line would be a greater challenge in Alternative 3. Using the existingalignment in phase 3 would require constructing the new bridge to the east in the first phase in order tokeep the natural gas line in service. If the structure were constructed to the west during the first phase ofconstruction, then the natural gas line would require multiple shifts from one side of the bridge to the other.Once the expansion to the east is completed, the natural gas line would be relocated to the east side of thestructure. This would require the gas line to cross under CR 5500 from west to east and back to the westafter the bridge. This complexity makes this alternative much less attractive than Alternatives 1 and 2.

Alternatives 1 and 2 would require additional right-of-way. The utility poles supporting the overheadelectrical and communication lines will require relocating to the west side of the new right-of-way.

7.11 Construction CostsUsing the alternative layouts as developed and illustrated in Appendix A, and with conceptual design ofroadway alignments, quantities of the major construction bid items have been calculated for eachalternative to estimate the construction costs of each. Along with the construction bid item costs,construction engineering, utility relocation, right-of-way acquisition and New Mexico Gross Receipts Taxhas been calculated and added to the overall construction cost estimates to arrive at total project costs.The three (3) alternatives present a range of costs. The major difference between the alternatives is thecost of constructability and phased construction reflected in bridge costs and maintenance of traffic (MOT)costs required for detours during construction sequencing. Refer to Table 7.11 below for construction costsof each alternative.

Table 7.11. Construction Cost Estimates

Alternative Estimated RoadwayCost

Estimated Cost ofStructure

Estimated TotalProject Cost

Alternative 1 –20’ Alignment Shift, Steel

Option

$717,000 $2,948,000 $5,217,000

Alternative 1 –20’ Alignment Shift,

Concrete Option

$732,000 $2,338,000 $4,482,000

Alternative 2 –8’ Alignment Shift, Steel

Option

$717,000 $2,948,000 $5,217,000

Alternative 2 –8’ Alignment Shift,Concrete Option

$732,000 $2,338,000 $4,482,000

Alternative 3 – ExistingAlignment, Steel Option

$781,000 $2,953,000 $5,302,000

Alternative 3 – ExistingAlignment, Concrete

Option

$796,000 $2,343,000 $4,568,000

8. Environmental Analysis of AlternativesThis section provides an evaluation of the project alternatives based on their impacts to environmentalresources and community services. The Existing Environmental Conditions Section 4.3 of this reportprovides a summary of environmental issues within the project area and identifies which ones would besignificant when evaluating alternatives. While all environmental concerns will be addressed in thesubsequent National Environmental Policy Act (NEPA) document and a Clean Water Act Section 404Nationwide Permit #14, a few concerns were identified that may vary among the alternatives and contributeto identifying a preferred alternative.

The habitat impacts are for general wildlife within the project area. Gunnison’s prairie dog burrowsencroach into the right-of-way and under the roadway surface north of the bridge. These are part of theprairie dog town northeast of the project area. There is a potential for impacts to nesting birds within theproject limits. It is anticipated that the birds will simply avoid the area once construction starts and there willbe no impact to nesting.

Wetlands have been identified on the northwest quadrant of the project area. Depending on the alignmentselected, the wetlands could be impacted.

Community services impacts would also include the emergency response services provided by the SanJuan County Fire Department. District 6 of the Department serves Lee Acres, within which the project islocated. District 6 comprises 39 square miles, much of which is south of the San Juan River. The onlycurrent fire station in District 6 is north of the river, located on CR 5500 between the river and US Highway64. A new fire station is planned and construction is starting on it in the summer of 2017. This station isalso being located on CR 5500, about four miles southeast of the Project site. With construction starting in2017, it will not be available for operation until sometime in late 2018. Therefore, for most of the coming


24

year, emergency services from the Lee Acres Fire Station that are needed in the south portion of LeeAcres rely on the river crossing at Bridge 8130.

8.1 Alternative 1 – 20’ Alignment ShiftVegetation and Habitat: The alternative may have an impact to the wetland located on the northwestquadrant of the project site.

Community Services and Right-of-Way: This alternative provides the least initial impact to traffic and toemergency response services, with Phase 1 construction to provide two (2) lanes for traffic on the newbridge while traffic continues to flow on the existing bridge. Traffic operation is virtually unaffected. Thisalternative has the potential to have the greatest impact to right-of-way, utilities and the wetlands but all toa reasonable degree. The roadway profile would be adjusted to tie to the existing roadway prior to the firstintersection to the north and south to minimize earthwork to the intersections and driveways.

8.2 Alternative 2 – 8’ Alignment ShiftVegetation and Habitat: This alternative will minimize the impacts to the wetlands located on the northeastquadrant of the project due to close proximity to the existing alignment.

Community Services and Right-of-Way: This alternative exhibits impacts related to traffic flow duringconstruction. Following initial construction, traffic will be split with one lane on the old bridge and one laneon the new bridge. Traffic flow will be slowed with low “detour” speeds and with the narrow availableroadway widths. The smaller, concentrated but more restrictive work zone, will pose potential concerns fortraffic operation beside construction operations, with the probable need for short term closures of the roadwhile shifts are made and while girders are placed. This alternative therefore does pose concerns for trafficand emergency response use, and is less desirable than Alternative 1.

8.3 Alternative 3 – Existing AlignmentVegetation and Habitat: This alignment minimizes the impacts to the vegetation and habitat since it usesthe existing alignment. There would be very minor impacts due to widening of the bridge and roadway.

Community Services and Right-of-Way: This alternative also exhibits impacts related to traffic flow duringconstruction, with greater impacts than the other alternatives. With use of the same alignment, the workzone is very small and restrictive, with traffic set up with one-way operation directly beside constructionoperations. Use of this configuration may be detrimental to emergency service providers. While flaggercontrol could be responsive to approaching emergency vehicles when sirens are heard, traffic signal usewould require pre-emption for emergency vehicles. The District 6 Fire Station’s vehicles are not set up withpre-emption equipment. This alternative therefore does pose concerns for traffic flow, and is fairlyrestrictive to emergency services.

8.4 No BuildThe no build alternative would have no impact to vegetation and habitat, or community resources and right-of-way. The deteriorating condition of the bridge does however, pose a concern for emergency vehicle use.The no build alternative does not satisfy the project purpose and need and is considered here as abaseline for comparison of other alternatives.

8.5 SummaryThe amount of right-of-way needed for each alternative varies with the right of way needed beingproportional to the greater offset of new alignment from existing alignment. None of the alternativesinvolves relocations or an excessive amount of right of way.

Impacts to community services, focused on emergency service providers, is considerably different betweenalternatives. Alternative 1 has little to no impact to emergency services; Alternative 2 does impose somerestrictions to traffic and emergency services, while Alternative 3 has a fairly significant impact.

This analysis addressed environmental justice and Title VI concerns where right-of-way or relocations maybe required from special status populations. None of the alternatives would affect special statuspopulations. 9.0Evaluation Criteria and Evaluation of Alternatives

9. Evaluation CriteriaAlternative evaluation criteria were categorized under six (6) primary categories: 1) Purpose and Need; 2)Traffic Operations and Safety; 3) Access and Mobility; 4) Constructability and Maintenance; 5)Environmental and Community Impacts; and 6) Costs and Land Impacts. These categories generallyaddress the key measures of performance that were used and needed to differentiate and evaluatealternatives. Each of the categories was further broken down into performance criteria as described below.The categories were assigned weights, which at this level is the sum of the weights for the individualcriteria within each category. A 100-point total system was used, so that the weights effectively representthe percent emphasis assigned to each category and criteria. Weights for each criteria are also describedbelow.

Purpose and Need

All alternatives, with the exception of the No Build alternative, are considered to satisfy the Project Purposeand Need. Therefore, a relatively low weighting is allocated to this criteria – 5 points or 5%, therefore, moredetail is considered unnecessary. The alternatives are ranked based on how well they address PhysicalDeficiencies, Safety and Multi-Modal System Connectivity.

Traffic Operations and Safety

All of the alternatives, with the exception of the No Build alternative, meet the needs for traffic operationsand safety. The No Build alternative meets the current traffic operations, but due to the lack of adequateshoulders and pedestrian amenities, it does not meet the safety requirements for the project area. Arelatively low weighting is allocated to this criteria – 5 points or 5%, therefore more detail is consideredunnecessary.

Access and Mobility

Access and Mobility represents the use of the project corridor by multiple modes of transportation andmaintaining the opportunity to traverse the corridor while satisfying the Americans with Disabilities Act(ADA) requirements. The Pedestrian Accommodations criteria is evaluated on the capacity of eachalternative to provide safe pedestrian travel across the corridor. This criteria is assigned 5 points or 5%.

Constructability and Maintenance

Constructability and Maintenance represents the critical issue of actually constructing an alternative whilemaintaining traffic on the existing roadway. This criteria represents the importance of minimizing stagedconstruction, especially of the bridge structure, in order to minimize traffic and emergency responseimpacts, and in order to obtain a better facility by reducing the number of construction joints. All of thealternatives require construction phasing, but those that can be constructed while minimizing the number ofphases and maintaining traffic on the existing roadway are preferable. One of the elements that will affectconstruction phasing is the grade difference between existing and new profile. With a grade difference of


25

approximately 38 1/2” for steel or 53 1/2" for concrete, construction phasing could potentially create anunsafe condition of steep side slopes, requiring measures such as temporary concrete wall barrier,(TCWB). Relocating the gas line will be included in the phasing to maintain service. This category isassigned 40 points or 40% of the overall rating.

Constructability and Maintenance is subdivided into the following two criteria: Construction Phasing /Maintenance of Traffic, assigned 20 points; Maintenance Concerns, assigned 20 points. These criteria aregenerally subjective, with the alternatives with the greatest complexity and impact being ranked lower, andthose with the least complexity and impact being ranked higher.

Environment and Community Impacts

Environment and Community Impacts can often be a significant concern and determining factor in certainprojects. Alternatives that avoid impacts and are the most acceptable to a community would rate quitedifferently than those with significant impacts. All alternatives have the environmental impacts for thiscategory and will be assigned a total of 10 points or 10% of the overall evaluation. This category is dividedinto two criteria: Overall Area of Disturbance to Vegetation and Habitat, assigned 5 points, and PublicPerception, assigned 5 points.

Overall Disturbance to Vegetation and Habitat is quantified by the area of impact of the total projectfootprint less the existing pavement areas. A positive ranking applies to those alternatives with smallerfootprint, negative rankings apply to alternatives with larger footprint.

As discussed in Section 8, community services impacts include the emergency response services providedby the San Juan County Fire Department. District 6 of the Department serves Lee Acres, within which theproject is located. Emergency services from the Lee Acres Fire Station are needed in the south portion ofLee Acres and rely on the river crossing at Bridge 8130.

Cost and Land Impacts

All of the alternatives were evaluated for cost. This category is subdivided into two criteria: Right of WayAcquisition assigned as 5 points, and Overall Project Cost assigned as 15 points. This category overall isvalued at 20 points or 20% of the overall rating.

Overall Rating

The results of the evaluation and summation of ratings ranks Alternative 1 as the most desirable alternativewith a score of 70 points. Alternative 2 ranks second with 61 total points. Alternative 3 scored the lowestdue to various factors including more construction stages, resulting in a longer timeframe for construction.The No-Build alternative is clearly an undesirable result, with 50 points total. Refer to Table 9.1.


26

Table 9.1 Evaluation Matrix

Evaluation Criteria (weighted 100points total)

Alternative 1 – Alignment Shift20’ West

Points Alternative 2 – Alignment Shift8’ West

Points Alternative 3 – ExistingAlignment

Points No-Build Points

Purpose & Need(5 points total)

Physical Deficiencies, TravelDemand, Safety

Meets Purpose & Need,addresses travel demand, loadrating, pedestrian and bicycle

safety.

5 Meets Purpose & Need,addresses travel demand, loadrating, pedestrian and bicycle

safety.

5 Meets Purpose & Need,addresses travel demand, loadrating, pedestrian and bicycle

safety.

5 Does not satisfy Purpose &Need. No improvements,

therefore, Project Need is notaddressed.

0

Traffic Operations and Safety(5 points total)

Meets traffic demand in the 2040horizon year

Operates at adequate level ofservice. Accommodates future

traffic demand.

5 Operates at adequate level ofservice. Accommodates future

traffic demand.

5 Operates at adequate level ofservice. Accommodates future

traffic demand.

5 Does not satisfy traffic demandof truck traffic. Roadway sectionhas inadequate shoulders withno facilities for pedestrians or

bicyclists.

0

Access and Mobility(5 points total)

Pedestrian and bicycleaccommodations

Pedestrian friendly, sharedfacility with bicycles.

5 Pedestrian friendly, sharedfacility with bicycles.

5 Pedestrian friendly, sharedfacility with bicycles.

5 There are no pedestrianfacilities. There are no bicycle

lanes or multiuse path. No-Buildalternative does not address

deficiencies.

0

Constructability and Maintenance(40 points total)

Construction Phasing (20 points) Staged construction is lesscomplicated than other

alternatives. Alternative includes4 phases of construction

beginning with new constructionof bridge adjacent to existing.Phase 2 will accommodate 2lanes of traffic with traffic shiftfrom existing to new bridge,

allowing both directions of trafficto be switched to new bridge

while existing bridge isdemolished. Subsequent phasesof construction will add width to

the new bridge. Advantageincludes no grade separation

between directions of traffic andlimited reroutes of traffic.

15 Staged construction iscomplicated will require 6

phases of constructionsequencing. In phase 1, a

portion of the new bridge isconstructed, then southbound

traffic is switched to new bridge.Close horizontal alignment

between phases requires TCWBat top and bottom of the steep

slope due to differences invertical profile. Bridge wideningis similar to Alternative 1. After

construction of phase 2, alltraffic will be on the new bridgeand the existing bridge will be

demolished.

10 Staged construction iscomplicated and will require 5

phases of constructionsequencing. Shared use of

single lane is required while aportion of the existing bridge isdemolished and a portion of the

new bridge is constructed.Shared use lane will require

temporary signal. Constructionof the new bridge is limited dueto width that can be demolished

based on girder spacing.

10 No-Build requires noconstruction sequencing.

20


27

Maintenance Concerns (20 points) This alternative would result inthe fewest number of

longitudinal joints due to thephased construction.

20 Alternative 2 will requireincreased maintenance due to

increased longitudinal joints

15 This alternative would have themost construction joints, with

potential for maintenanceproblems in the future.

10 The No-Build alternative wouldrequire increased maintenance

the longer the bridge is notreplaced.

0

Environmental and CommunityImpacts (10 points total)

Overall disturbance to vegetationand habitat (5 points)

Alternative 1 has the potentialfor the most impact to vegetationwithin the project area due to theproximity of the wetlands locatedon the northwest quadrant of the

project.

1 Alternative 2 would have a slightincrease of impacts to

vegetation disturbance overAlternative 3, with a new

alignment shift of 8’.

3 Alternative 3 would have theleast impact to vegetation

disturbance due to widening ofexisting roadway only for project

compared to the width of theexisting roadway.

4 The No-Build alternative wouldhave the least impact to existing

vegetation since there is noconstruction.

5

Public Perception (5 points) This alternative would be theleast disruptive to the travelingpublic, with the least number of

shifts to traffic. The perception ofthe public would be positive for

bridge replacement withincreased safety as a result ofwidening for pedestrians and

bicyclists.

5 This alternative would provide apositive attitude towards the

replacement of the bridge. Theperception of the county and

engineering staff would not bepositive towards the delays andincreased congestion as a result

of the traffic shifts.

4 This alternative would be viewedas negative towards the bridgereplacement due to an increase

in traffic congestion andconstruction contract time.

1 The No-Build alternative doesnot address the replacement of

the bridge, therefore, theperception of the public would

not be positive.

0

Cost and Land Impacts (20 pointstotal)

Right-of-way required 1 Right-of-way required 1 No right-of-way required 5 No right-of-way required 5

Right of Way Acquisition (5 points) Alternative 1 has the potentialfor most impact for right-of-way

acquisition.

1 Alternative 2 has decreasedpotential for right-of-way

acquisition due to proximity ofthe existing right-of-way.

1 Alternative 3 has the potentialfor the least impact to right-of-

way.

5 The No-Build alternative doesnot address an increase to right-

of-way widths.

5

Overall Project Cost (15 points) Steel - $5.217MConcrete - $4.482M

12 Steel - $5.217MConcrete - $4.482M

12 Steel - $5.302MConcrete - $4.568M

6 No construction costs. 15

Overall Rating / Grand Total Points 70 61 56 50

Deficient <40 points Performs Poorly 40 – 45 points Neutral 46 – 55 points Performs Well 56 – 60 points Superior > 60 points

Definitions of Rating Spread / Points Assignment

Deficient (points as shown within each category above, overall summation <35 points) – fails to satisfy the criteria, points assigned as zero (0) or at/near the bottom of the number of total points available.

Preforms poorly (points as shown within each category above, overall summation 35 – 44 points) – performance is generally inadequate, points assigned in the bottom third of the total points available

Neutral (points as shown within each category above, overall summation 45 – 55 points) – satisfies most criteria, performance is adequate, points assigned at or near the mid-point of the total points available

Performs Well (points as shown within each category above, overall summation 56 – 65 points) – performance is good, points assigned in the upper third of the total points available

Superior (points as shown within each category above, overall summation >65 points) – performance is outstanding, points assigned at/near the top of the number of points available


28

10.Conclusions and Recommendations10.1 Preferred Alternative

Based on the analysis described in Section 7 and 8, and the evaluation and ranking of alternativesdescribed in Section 9, the Preferred Alternative for the reconstruction of Bridge 8130 on County Road5500 is Alternative 1, with offset of approximately 20’ west of the existing alignment, with concrete girders.This alternative works very well from the perspective of both “Purpose and Need” and “Constructability andMaintenance”. In the sub-category of “Construction Phasing” and “Maintenance Concerns”, this alternativedemonstrates “Superior” performance. Relative to costs, this alternative demonstrated “Superior”performance. Alternative 1, with concrete option is ranked the highest of all the alternatives evaluated.

The purpose and need of this project is to replace Bridge 8130 with a bridge that meets current designstandards, provides safety for pedestrians and bicyclists and meets future traffic in 2040.

CR 5500, REPLACEMENT OF BRIDGE 8130 OVER SAN JUAN RIVER

Phase IA/B Detailed Evaluation of Alternatives

I:/Projects/Transportation/60534372_CR5500SJC/400-Technical/410-TAR/Phase 1A Report

Appendix A

Conceptual Design Drawings:

Alternative 1 Layout



CR 5500 Existing and Proposed Bridge Profile Views

Typical Sections – Concrete

Typical Sections – Steel

Construction Phases 1 and 2 – Alternative 1






Construction Phases 3, 4, and 5 – Alternative 3

cr 5500, replacement of bridge 8130 over san … · cr 5500, replacement of bridge 8130 over san...

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