Appendix 2

NOISE ANALYSIS

NOISE IMPACT ANALYSIS

TECHNICAL REPORT

RTE 58 - Corridor Development Program - 4 Lanes Patrick County

PROJECT: 0058-070-E18/E19

UPC’s: 17536, 17537

From: Meadows of Dan Bypass

To: Stuart Bypass

Prepared by: Lovejoy Muchenje

Noise Abatement Engineer

Environmental Division Virginia Department of Transportation

March, 2010

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TABLE OF CONTENTS

I. Summary................................................................................................................................ 3 II. Introduction........................................................................................................................... 4 III. Guidelines and Criteria ........................................................................................................ 7 IV. Noise Model and Projections ............................................................................................... 9 V. Noise Impact Assessment ................................................................................................... 13

A. Existing Conditions........................................................................................................... 13

C. Design (2035) Build Conditions ....................................................................................... 14 VI. Noise Abatement ................................................................................................................. 16

A. Alignment Modification and Traffic Management............................................................ 16

B. Sound Barriers .................................................................................................................. 17 VII. Noise Contours .................................................................................................................... 20 VIII.Construction Noise ............................................................................................................. 20

TABLES AND FIGURES

Figure 1: Route 58 – Corridor Development Project Location Overview............................... 6 Table 1: FHWA Noise Abatement Criteria............................................................................... 8 Table 4: Noise Level Summary................................................................................................. 10

APPENDICES

Appendix A: Graphic Sheets .................................................................................................…..A

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I. Summary Potential traffic noise impacts associated with the Route 58 corridor development project were

assessed in accordance with procedures and criteria approved by the Federal Highway

Administration (FHWA) and the Virginia Department of Transportation (VDOT). The project

involves expanding the existing Route 58 to a four lane roadway from the Meadows of Dan

Bypass to the Stuart Bypass. A project location map is shown in Figure 1.

A two-dimensional (2-d) analysis was used for the noise modeling. Terrain features were not

included, which assumes a worst-case scenario. Using the existing and proposed typical

sections, the 66 dBA contour lines for the existing and proposed case were modeled. The two 66

dBA noise contour represent the existing and proposed worst case noise exposure throughout the

project area. Any noise sensitive properties within the 66 dBA contour should be considered

noise impacted.

One hundred-six receptor sites were investigated for noise impacts. These sites include single

family homes, a tennis court, two cemeteries and one church. No noise impacts are predicted to

occur in the existing year. Thirty-three sites, representing 57 single family homes, are predicted

to be noise impacted in the design year (2035) due to levels approaching or exceeding the Noise

Abatement Criteria (NAC). Noise mitigation for these sites by means of a barrier is not feasible

since all impacted sites have direct access to the roadway, which prohibits the construction of a

feasible noise barrier. However, the findings presented in this report are based on conceptual

design information, and are not considered final. All areas shall be reevaluated during the Final

Design phase of the project.

Construction activity may cause intermittent fluctuations in noise levels. During the

construction phase of the project, all reasonable measures will be taken to minimize noise impact

from these activities.

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II. Introduction

The objective of this analysis was to assess the potential traffic noise impact associated with the

widening of Route 58 and to evaluate noise abatement measures wherever impact is expected to

occur. The project location is shown in Figure 1.

The project involves expanding the existing Route 58 to a four lane roadway. Beginning at the

end of the recently constructed Meadows of Dan Bypass, the preferred alternative for the

proposed improvements to Route 58 include constructing four new lanes for the majority of the

corridor eastward to the beginning of the Stuart Bypass. Constraints including terrain,

residential and commercial development, wetlands, parks, historical sites, and river crossings

precluded the use of the vast majority of existing Route 58 in this portion of the corridor.

At Route 795, the Preferred Alternative proposes to shift Route 58 slightly to the south of

existing Route 58 with the exception of two sections just east and west of the Dan River

crossing. Aside from the River crossing itself, the historic Blackard-Spangler historic property

and industrial property to the east of the river crossing (Aerial Corporation) are constraining

issues.

Continuing east the Preferred Alternative shifts further away from Route 58 to the south

avoiding the Mountain Top Recreation Park and residential impacts near Hylton’s Store. The

alignment then shifts to the north of Existing Route 58 to avoid the community of Vesta and

multiple residential impacts that would occur by following existing Route 58. This alignment

also avoids wetlands impacted by other alternatives and is the shortest alignment from a design

standpoint. The Preferred Alignment once again joins existing Route 58 in the vicinity of Route

610 east of Vesta.

From Route 610 heading eastward, the Preferred Alternative enters the extremely rugged and

mountainous terrain known as Lover’s Leap. From Route 610 to Lover’s Leap, the Preferred

Alternative shifts south of the existing alignment to avoid terrain, the Fred Clifton Park, Radio

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Towers, and impacts to the Smith River drainage area due to concerns over the federally

endangered species, the Roanoke Logperch. A popular farm and market are also located in this

vicinity further constraining the location of the Preferred Alternative.

Near the actual site of Lovers Leap Overlook, the Preferred Alignment generally follows the

existing Route 58 to the point of a very sharp horizontal curve or switchback. At this point, the

east and westbound lanes diverge with the eastbound lanes following the southwestern side of

the valley well to the west of the existing alignment and the westbound lanes generally following

the existing two lane section of Route 58 to the bottom of the mountain near Route 640. This

allowed for grades of the downhill section of Route 58 to be considerably flatter (6.5% vs 8.5%)

and provided for significantly reduced earthwork. A very short section of existing Route 58

becomes the westbound lanes of the Preferred Alternative. Two truck escape ramps are planned

in this section of the roadway.

From Route 640 to Route 8, the Preferred Alternative generally follows the existing alignment of

Route 58 with minor corrections to horizontal and vertical alignment. Wetlands and stream

crossings encourage minor shifts in the alignment to avoid impacts to these areas. Near the

actual connection with Route 8, a slight shift to the south improves horizontal alignment and

improves the connection with Route 8.

Continuing East towards the Stuart Bypass, the Preferred Alternative generally follows the

existing alignment with while attempting to minimize impacts to the North Fork of the Mayo

River and it’s tributaries. This requires significant earthwork while widening away from the

River. Several residential properties and businesses further constrain the alignment as well.

Impact assessment has been performed for noise sensitive activities within project corridor,

which includes single family homes, commercial facilities and a cemetery. The study shows that

no noise impact is predicted to occur in the existing year. Thirty-three sites, representing 57

single family homes, are predicted to be noise impacted in the design year (2035) due to levels

approaching or exceeding the NAC. No noise impact is predicted to occur in the existing year.

This report presents a description of noise terminology, the applicable standards and criteria, a

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description of the computations of existing and future noise levels, a projection of future noise

levels, and a discussion of construction noise.

Figure 1: Route 58 – Corridor Development Project Location Overview

Begin Project

End Project

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III. Guidelines and Criteria

The potential noise impact of the proposed Route 58 project has been assessed in accordance

with FHWA guidelines published in Volume 7, Chapter 7, Section 2 of the Federal Aid Policy

Guide (FAPG 7-7-2) and with the State Noise Abatement Policy. In order to determine the

degree of impact of highway traffic noise on human activity, the NAC, Table 1, established by

FAPG 7-7-2 is used. The NAC, listed in Table 1 for various activities, represent the upper limit

of acceptable traffic noise conditions and also a balancing of that which may be desirable with

that which may be achievable. The NAC applies to areas having regular human use and where

lowered noise levels are desired. They do not apply to the entire tract of land on which the

activity is based, but only to that portion where the activity takes place.

The NAC is given in terms of the hourly, A-weighted, equivalent sound level in decibels (dBA).

The A-weighted sound level is a single number measure of sound intensity with weighted

frequency characteristics that correspond to human subjective response to noise. However, since

most environmental noise fluctuates from moment to moment, it is common practice to condense

all of this information into a single number called the equivalent sound level (Leq). The Leq is

the value of a steady sound level that would represent the same sound energy as the actual time-

varying sound evaluated over the same time period. For highway traffic noise assessment, Leq is

typically evaluated over a one-hour time period, and is denoted as Leq(h).

The noise impact assessment is made using the guidelines listed in Table 1. The noise sensitive

activities potentially affected by this project are in Category C. If, for a given activity, the

design year noise levels “approach or exceed” the NAC, then the activity is impacted and a

series of abatement measures must be considered. The VDOT State Noise Abatement Policy

defines “approach” as 1 dBA less than the NAC.

There is another criterion for assessing noise impact provided in the Federal guidelines. A

receiver can be noise impacted if the design year build noise levels are substantially higher than

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existing levels. The VDOT State Noise Abatement Policy defines a substantial increase as 10

dBA or more, even though the levels may not reach the NAC.

The final decision on whether or not to provide noise abatement along a project corridor will

take into account the feasibility of the design and overall cost weighted against the

environmental benefit.

Table 1: FHWA Noise Abatement Criteria

Hourly A-Weighted Sound Level Decibels (dBA)

Activity

Category Leq(h) Description Of Activity Category

A 57

(Exterior)

Lands on which serenity and quiet are of extraordinary significance and serve an

important public need and where the preservation of those qualities is essential if

the area is to continue to serve its intended purpose.

B 67

(Exterior)

Picnic areas, recreation areas, playgrounds, active sports areas, parks, residences,

motels, hotels, schools, churches, libraries, and hospitals.

C 72

(Exterior) Developed land, properties or activities not included in Categories A or B above.

D --- Undeveloped lands.

E 52

(Interior)

Residences, motels, hotels, public meeting rooms, schools, churches, libraries,

hospitals and auditoriums.

Source: 23 CFR Part 772

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IV. Noise Model and Projections Noise impact assessment has been performed for all noise sensitive properties within the project

corridor. Using the proposed typical sections and the traffic data, the 66 dBA contour lines were

modeled. The project has three proposed typical sections. Typical section one begins in the

eastern end of the project limits to the point where the proposed Route 58 begins to deviate from

the existing Route 58. Typical section one has four lanes and a median. Each lane has a width

of 3.6 m (12ft) and the median width of 7.2 m (24 ft). Typical section two begins in the area

where the proposed alignment begins to shift away from the existing Route 58 avoiding the

Mountain Top Recreation Park, to the area where the proposed alignment once again joins

existing Route 58 in the vicinity of Route 610 east of Vesta. Typical section two has two lanes

each with a width of 3.6m (12 ft). Typical section three begins in the area where the proposed

alignment joins existing Route 58, in the vicinity of Route 610, to the western end of the project

limits. Typical section three has four lanes each with a width of 3.6 m (12 ft). All three typical

sections were used to model the proposed 66 dBA lines in the different regions throughout the

project area. Any noise sensitive properties within the 66 dBA contour should be considered

noise impacted. The 66 dBA contour lines are shown as yellow and pink dashed lines in sheets 2

through 10 in Appendix A.

A review of the project corridor has established highway traffic as the dominant source of noise

for the build condition. Since highway noise can be determined accurately through computer

modeling techniques for areas that are dominated by road traffic, both existing and design year

traffic noise calculations have been performed using FHWA TNM® Version 2.5. FHWA TNM

® was developed and sponsored by the U. S. Department of Transportation and John A. Volpe

National Transportation Systems Center, Acoustics facility. The TNM computer model accounts

for such factors as ground absorption, roadway geometry, receiver distance, shielding from local

terrain and structures, vehicle volume, operating speed, and volumes of medium trucks (vehicles

with 2 axles and 6 tires) and heavy trucks.

A total of 106 noise sensitive sites were evaluated for purposes of noise prediction throughout

the project area. For reporting purposes, the project area was divided into areas of common

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noise environment, referred to as Noise Sensitive Sites (NSA’s). The NSA’s were divided based

on the proposed typical cross sections.

Assessment of traffic noise impact requires three comparisons:

(1) The noise levels under existing conditions must be compared to those under

design year build conditions. This comparison shows the change in noise levels that will

occur between the existing year and the design year if the project is constructed, to

determine if the substantial increase impact criteria has been met.

(2) The noise levels under design year build conditions must be compared to the

applicable NAC. This comparison determines if the impact criteria has been met under

future build conditions and can be used to assist in noise compatible land use planning.

The noise prediction results are summarized in Table 2. A no-build analysis was not completed

because the project is not on the interstate system, and does not involve a Section 4(f) analysis.

Table 2: Noise Level Summary Receiver Number Land Use Dwelling

Units

Sites Currently Impacted

Sites Impacted in 2035 Build

Noise Abatement

Criteria

Noise Impacted

NSA A-Typical Section 1 A1 Residential 2 0 0 66 No A2 Residential 1 0 0 66 No A3 Residential 2 0 0 66 No A4 Residential 3 0 0 66 No A5 Residential 1 0 1 66 Yes A6 Residential 1 0 0 66 No A7 Commercial NA 0 0 71 No A8 Residential 1 0 1 66 Yes

Residential 1 0 0 66 No A9 Commercial NA 0 0 71 No Residential 1 0 0 66 No A10 Commercial NA 0 0 71 No

A11 Residential 3 0 0 66 No A12 Residential 1 0 1 66 Yes A13 Residential 2 0 0 66 No A14 Commercial NA 0 0 71 No A15 Residential 2 0 0 66 No A16 Residential 1 0 0 66 No A17 Residential 3 0 0 66 No

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Receiver Number Land Use Dwelling

Units

Sites Currently Impacted

Sites Impacted in 2035 Build

Noise Abatement

Criteria

Noise Impacted

A18 Commercial NA 0 0 71 No A19 Residential 2 0 2 66 Yes A20 Residential 1 0 1 66 Yes

A21 Bouldin Memorial Cemetery NA 0 0 66 No

A22 Residential 1 0 1 66 Yes Residential 1 0 0 66 No A23 Commercial NA 0 0 71 No

A24 Residential 1 0 0 66 No Residential 5 0 5 66 Yes A25 Commercial NA 0 0 71 No

A26 Residential 1 0 1 66 Yes A27 Residential 1 0 0 66 No A28 Church with cemetery NA 0 0 66 No A29 Residential 2 0 0 66 No A30 Residential 2 0 2 66 Yes A31 Residential 2 0 0 66 No A32 Commercial NA 0 0 71 No

NSA B- Typical Section 2 B1 Residential 1 0 0 66 No

NSA C- Typical Section 3 C1 Residential 1 0 0 66 No C2 Commercial NA 0 0 71 No C3 Residential 1 0 0 66 No C4 Residential 1 0 0 66 No C5 Commercial NA 0 0 71 No C6 Residential 1 0 1 66 Yes C7 Residential 1 0 0 66 No C8 Residential 1 0 0 66 No C9 Residential 1 0 0 66 No C10 Commercial NA 0 0 71 No C11 Residential 1 0 1 66 Yes C12 Residential 1 0 0 66 No C13 Residential 2 0 2 66 Yes C14 Residential 1 0 0 66 No C15 Residential 1 0 0 66 No C16 Residential 2 0 2 66 Yes C17 Commercial NA 0 0 71 No C18 (2) Commercial NA 0 0 71 No C19 Residential 1 0 0 66 No C20 Residential 1 0 0 66 No C21 Residential 3 0 3 66 Yes

Residential 1 0 1 66 Yes C22 Commercial NA 0 0 71 No C23 Residential 4 0 0 66 Yes

Residential 2 0 2 66 Yes C24 (2) Commercial NA 0 0 71 No Residential 1 0 1 66 No C25 (2) Commercial NA 0 0 71 No

C26 Residential 1 0 0 66 No

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Receiver Number Land Use Dwelling

Units

Sites Currently Impacted

Sites Impacted in 2035 Build

Noise Abatement

Criteria

Noise Impacted

C27 Residential 3 0 3 66 Yes C28 Residential 0 0 66 No C29 Residential 0 0 66 No C30 Residential 4 0 4 66 Yes

Residential 3 0 3 66 Yes C31 Commercial NA 0 0 71 No C32 Residential 1 0 1 66 Yes C33 Residential 1 0 1 66 Yes C34 Residential 3 0 0 66 No C35 Residential 2 0 0 66 No C36 Residential 1 0 1 66 Yes C37 Residential 1 0 0 66 No C38 Commercial NA 0 0 71 No C39 Residential 1 0 0 66 No C40 Residential 2 0 0 66 No C41 Residential 3 0 3 66 Yes C42 Residential 6 0 0 66 No C43 Residential 2 0 0 66 No C44 Residential 1 0 1 66 Yes C45 Residential 1 0 0 66 No C46 Residential 2 0 0 66 No C47 Residential 2 0 2 66 Yes C48 Residential 1 0 1 66 Yes C49 Residential 2 0 0 66 No C50 Residential 2 0 2 66 Yes C51 Residential 2 0 2 66 Yes C52 Residential 1 0 0 66 No C53 Residential 1 0 0 66 No C54 Tennis court NA 0 1 66 Yes C55 Residential 4 0 0 66 No C56 Commercial NA 0 0 71 No C57 Residential 2 0 0 66 No C58 Residential 1 0 0 66 No C59 Commercial NA 0 0 71 No C60 Residential 1 0 0 66 No C61 Residential 1 0 1 66 Yes C62 Residential 10 0 0 66 No C63 Commercial NA 0 0 71 No C64 Residential 1 0 1 66 Yes C65 Residential 2 0 2 66 Yes C66 Residential 3 0 0 66 No C67 Residential 1 0 0 66 No

Residential 1 0 0 66 No C68 Commercial NA 0 0 71 No C69 Residential 3 0 0 66 No C70 Residential 2 0 0 66 No C71 (3) Commercial NA 0 0 71 No C72 Residential 1 0 0 66 No

Criteria based on levels “approaching” the absolute criteria

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V. Noise Impact Assessment

One hundred-six receptor sites in the three NSA’s were investigated for noise impacts. These

sites include single family homes, a tennis court, two cemeteries and one church. No noise

impact is predicted to occur in the existing year. Thirty three sites, representing 57 single family

homes, are predicted to be noise impacted in the design year (2035) due to levels approaching or

exceeding the NAC.

A. Existing Conditions No sites are predicted to have noise levels that approach or exceed the NAC in the existing

condition.

NSA A – Typical Section 1

NSA A begins in the eastern end of the project limits to the point where the proposed Route 58

begins to split up from the existing Route 58. Thirty three receptor sites, representing 48 single

family homes, two cemeteries, one Church and eight commercial facilities were studied for noise

impacts. Based on information on Geographic Information System (GIS) maps and Google

maps, the eight commercial facilities do not appear to have regular outdoor noise sensitive

activities. No noise impact is predicted to occur in the existing year for the studied receptor sites

in NSA A.

NSA B – Typical Section 2

NSA B begins in the area where the proposed alignment begins to shift away from the existing

Route 58 avoiding the Mountain Top Recreation Park, to the area where the proposed alignment

once again joins existing Route 58 in the vicinity of Route 610 east of Vesta. One receptor site,

representing one single family homes, was studied for noise impacts. No noise impact is

predicted to occur in the existing year for the studied receptor site in NSA B.

NSA C – Typical Section 3

NSA C begins in the area where the proposed alignment joins existing Route 58, in the vicinity

of Route 610, to the western end of the project limits. Seventy two receptor sites, representing

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110 single family homes, one tennis court and 18 commercial facilities were studied for noise

impacts. Based on information on Geographic Information System (GIS) maps and Google

maps, the 18 commercial facilities do not appear to have regular outdoor noise sensitive

activities. No noise impact is predicted to occur in the existing year for the studied receptor sites

in NSA C.

C. Design (2035) Build Conditions Thirty three sites, representing 57 single family homes, are predicted to be noise impacted in the

design year (2035) due to levels approaching or exceeding the NAC.

NSA A – Typical Section 1

NSA A begins at the eastern end of the project limits to the point where the proposed Route 58

begins to split up from the existing Route 58. Thirty three receptor sites, representing 48 single

family homes, two cemeteries, one church and eight commercial facilities were studied for noise

impacts. Nine receptor sites, representing 15 single family homes, are predicted to be noise

impacted in the design year (2035). However, all the impacted residential sites have direct

access to the roadway, which prohibits the construction of a “feasible” noise barrier.

Based on information on Geographic Information System (GIS) maps and Google maps, the

eight commercial facilities do not appear to have regular outdoor noise sensitive activities. No

commercial sites are predicted to experience noise levels that approach the 72 dBA (NAC) for

commercial sites (Activity Category C in Table 1) both in the exiting year (2008) and the design

year (2035).

The church is represented by A28. The church has a cemetery, also represented A28. The

cemetery is outside both the existing and the proposed 66 dBA contour line, and therefore is not

impacted in the existing and the design year (2035).

Since the exterior for the church appears to be composed of masonry material and modern air

conditioning is installed (information from Google maps), the reduction in noise levels in the

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church interior as a result of the building is predicted to be 25 dBA (FHWA “Highway Traffic

Noise Analysis and Abatement Policy and Guidance,” June 1995). Therefore the design build

indoor noise levels in the church are not predicted to approach or exceed the NAC under

Category E activity.

NSA B – Typical Section 2

NSA B begins in the area where the proposed alignment begins to shift away from the existing

Route 58 avoiding the Mountain Top Recreation Park, to the area where the proposed alignment

once again joins existing Route 58 in the vicinity of Route 610 east of Vesta. One receptor site,

representing one single family homes, was studied for noise impacts. No noise impacts are

predicted to occur in the design year for the studied receptor site in NSA B

NSA C – Typical Section 3

NSA C begins in the area where the proposed alignment joins existing Route 58, in the vicinity

of Route 610, to the western end of the project limits. Seventy two receptor sites, representing

110 single family homes, one tennis court and 18 commercial facilities were studied for noise

impacts. Twenty four receptor sites, representing 42 single family homes, are predicted to be

noise impacted in the design year (2035). However, all the impacted residential sites have direct

access to the roadway, which prohibits the construction of a “feasible” noise barrier.

Based on information on Geographic Information System (GIS) maps and Google maps, the

eight commercial facilities do not appear to have regular outdoor noise sensitive activities. No

commercial sites are predicted to experience noise levels that approach the 72 dBA (NAC) for

commercial sites (Activity Category C in Table 1) both in the exiting year (2008) and the design

year (2035).

Note: All the noise sensitive sites are based on information on the GIS maps and Google maps.

A thorough field review to quantify all sites shall be carried out in the Final Design phase of the

project.

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VI. Noise Abatement Design year noise levels have been predicted to approach or exceed the VDOT NAC in a number

of areas throughout the project corridor. Therefore, per VDOT’s State Noise Abatement Policy,

noise abatement considerations are warranted for these areas. Noise abatement alternatives were

considered to reduce noise levels in the areas identified with design year noise impacts, and

potential mitigation measures were evaluated for feasibility and reasonableness.

VDOT guidelines recommend a variety of mitigation measures that should be considered in

response to transportation-related noise impacts. While noise barriers and/or earth berms are

generally the most effective form of noise mitigation, additional mitigation measures exist which

have the potential to provide considerable noise reductions, under certain circumstances.

Mitigation measures considered for this project include:

• Construction of noise barriers; • Construction of earth berms; • Acoustical insulation of public use and non-profit facilities; • Alignment modifications; and • Traffic Management

A. Alignment Modification and Traffic Management The alteration of the horizontal and vertical alignment has been considered to reduce or eliminate

the impacts created by the proposed project. However, the alteration of vertical alignment is not

feasible for this project as the existing terrain features do not allow for placing the entire

roadway into a cut. Shifting the horizontal alignment away from the impacts is not feasible

because the proposed project occurs in the existing roadway footprint.

Traffic management measures that have been considered in conjunction with this project include

reduced speeds and truck restrictions. Truck restrictions are not practical since this facility

would be a route used by local truck traffic. Reducing speeds will not be an effective noise

mitigation measure since a substantial decrease in speed is necessary to provide adequate noise

reduction. Typically, a 10 mph reduction in speed will result in only a 2 dBA decrease in noise

level, which would not eliminate all impacts.

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B. Sound Barriers The impacted properties in the project area consist of multiple access points; noise barriers were

not considered a viable mitigation option.

Noise walls and earth berms are often implemented into the highway design in response to the

identified noise impacts. The effectiveness of a freestanding (post and panel) noise barrier and

an earth berm of equivalent height are relatively consistent; however an earth berm is perceived

as a more aesthetically pleasing option. The use of earth berms is not always an option due to

the excessive space they require adjacent to the roadway corridor. At a standard slope of 2:1,

every one-foot in height would require four feet of horizontal width. This requirement becomes

more complex in urban settings where residential properties often abut the proposed roadway

corridor. In these situations, implementation of earth berms can require significant property

acquisitions to accommodate noise mitigation. The cost associated with the acquisition of

property to construct a berm can significantly increase the total costs to implement this form of

noise mitigation.

Availability of fill material to construct the berm also needs to be considered. On proposed

projects where proposed grading yields excess waste material, earth berms are often cost

effective mitigation options. On balance or borrow projects the implementation of earth berms is

often an expensive solution due to the need to identify, acquire, and transport the material to the

project site.

As a general practice, noise barriers are most effective when placed at a relatively high point

between the roadway and the impacted noise sensitive land use. To achieve the greatest benefit

from a potential noise barrier, the goal of the barrier should focus on breaking the line-of-sight

(to the greatest degree possible) from the roadway to the receiver. In roadway fill conditions,

where the highway is above the natural grade, noise barriers are typically most effective when

placed on the edge of the roadway shoulder or on top of the fill slope. In roadway cut

conditions, where the roadway is located below the natural grade, barriers are typically most

effective when placed at the top of the cut slope. Engineering and safety issues have the

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potential to alter these typical barrier locations.

The effectiveness of a noise barrier is measured by examining the barrier’s capability to reduce

future noise levels. Noise reduction is measured by comparing design year pre- and post-barrier

noise levels. This difference between unabated and abated noise levels is known as insertion

loss (IL). The following discussion presents potential mitigation measures for each of the

impacted noise sensitive land uses.

According to VDOT guidelines, potential mitigation measures must also be assessed for

feasibility and reasonableness. Noise barrier feasibility deals specifically with acoustical and

engineering considerations such as:

• Noise barriers must reduce design year noise levels by 5 dBA for impacted sites; • The barrier cannot deny access to local vehicular and/or pedestrian travel; and • There cannot be significant engineering and/or safety problems associated with the

barrier which preclude construction of the barrier (engineering, safety, and utility conflicts)

Noise barrier reasonableness is determined by assessing multiple issues including:

• The number of units protected; • The desires of those citizens affected by the barrier; • A comparison of existing and future noise levels; • Total barrier cost and cost per protected and benefited property; • Barrier constructability and maintainability; and • Barrier impacts to utilities and drainage

Typically, the limiting factor related to barrier reasonableness is cost per protected dwelling unit,

where a protected and/or benefited receptor receives at least a 5 dBA reduction in noise level.

VDOT’s current approved cost is $30,000 per protected and/or benefited residence.

When a barrier exceeds the State Noise Abatement Policy’s cost-effectiveness criteria, third

party funding is required for the barrier to continue towards construction. FHWA and VDOT

contribute the first $30,000 for each protected or benefited property. The remainder must come

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from any source other than FHWA or VDOT. Final approval of all barriers will take into

account the views of the impacted property owners. The final determination of a barrier's cost

effectiveness will be based on the following:

• For residential properties, a barrier is cost effective when the cost does not exceed $30,000 per protected or benefited residential unit.

• An impacted property is considered protected when it receives a noise reduction of at least 5 decibels.

• Should a non-impacted property receive 5 dBA or more of noise reduction then the property will be considered benefited and included in the cost per protected site equation.

For non-residential properties such as parks, schools, and churches, the $30,000 cost criterion

does not apply. The determination is based on cost, severity of impact (both in terms of noise

levels and the size of the impacted area and the activity it contains), and amount of noise

reduction.

Another important component in noise barrier design is that a noise barrier should be continuous

without openings or gaps. Introducing openings into noise barriers to allow for driveways,

intersecting streets, or pedestrian access can quickly compromise the effectiveness of a noise

barrier. Because the impacted properties in the project area consist of multiple access points,

noise barriers were not considered a viable mitigation option.

Note: House Bill 2577 shall be given consideration in the Final Design phase of the project.

“House Bill 2577 States: Requires that whenever the Commonwealth Development Board (CTB)

or the Department plan for or undertake any highway construction or improvement project and

such project includes or may include the requirement for the mitigation of traffic noise impacts,

consideration should be given to the use of noise reducing design and low noise pavement

materials and techniques in lieu of construction of noise walls or sound barriers. Landscaping in

such a design would be utilized to act as a visual screen if visual screening is required.”

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VII. Noise Contours

Noise contours are lines of equal noise exposure that parallel the roadway noise source, and

diminish in intensity with distance. For the existing year and the design year (2035) build case,

the location of the 66 dBA noise contour line was determined for areas along the project corridor

for the purpose of characterizing the noise environment in the study area. Table 3 shows the

approximate worst-case distance between the 66 dBA lines and the roadway. The 66 dBA noise

contour lines for the existing case and the design year build (2035) are illustrated in sheets 2

through 10 in Appendix A. Any noise sensitive properties within the 66 dBA contour should be

considered noise impacted if no noise barrier is present to reduce noise levels.

Table 3: Distance of the 66 dBA contour line from roadway

NSA’s Distance of exiting 66 dBA from existing

center line (from edge of pavement) ft Distance of proposed 66 dBA from proposed

center line (from edge of pavement) ft NSA A 75 (63) 125 (100) NSA B 75 (63) 75 (53) NSA C 75 (63) 111 (89)

VIII. Construction Noise

Land uses that will be sensitive to traffic noise will also be sensitive to construction noise. A

method of controlling construction noise is to establish the maximum level of noise that

construction operations can generate. In view of this, VDOT has developed and FHWA has

approved a specification that establishes construction noise limits. This specification can be

found in VDOT's January 2007 Road and Bridge Specifications, Section 107.16(b.3), ″Noise″.

The contractor will be required to conform to this specification to reduce the impact of

construction noise on the surrounding community.

Appendix A