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SENTILLAS RUCHENETTE IGOT NESTOR

FERNANDEZ JUNJEEAR SAYSON

HIGHWAY.ENGINEERING

CHAPTER.4

HIGHWAYEVALUATION

HIGHWAY EVALUATIONIn the United States up until about 1950, highway engineers often were able to select desirable highway projects and plan, design, and construct them primarily on the basis of engineering and travel demand factors. Engineers, and the public as well, understood the need for extensive improvements to the highway system and recognized the considerable benefits from such projects.

ECONOMIC STUDIES FOR HIGHWAY PURPOSES ARE DONE PRINCIPALLY FOR ONE OR MORE OF THE FOLLOWING REASONS:

To determine feasibility of a project

To compare alternative locations

To evaluate various features of highway design

To determine priority of improvement

To allocate responsibility for the costs of highway improvement among the various classes of highway users

Occasionally, to compare proposals for highway improvement with proposals for other public projects such as education

COST OF HIGHWAY TRANSPORTATION

Highway transportation cost -is defined as the sum of the highway investment cost, the maintenance and operating costs, and the highway user costs. Highway investment cost- is the cost of preparing a highway improvement for service including the cost of rights-of-way, engineering design, construction, and traffic control devices.Maintenance cost- is the cost of preserving a highway and its appurtenances and keeping the facility in serviceable condition.Operating costs- include the costs of traffic control and lightingTransit capital costs- are the investments in fixed facilities for bus transit such as terminals, shops, bus parking facilities, and passenger benches and shelters.

HIGHWAY USER COSTSIncludes: motor vehicle

operating costs

the value of travel time

traffic accident cost

VALUE OF TRAVEL TIME is the product of the total

vehicle-hours of travel and the average unit value of time. The magnitude of travel time depends on average running speed and the number and duration of stops. Studies have indicated that the perceived value of ravel time is sensitive to trip purpose and time saving per trip.

NATIONAL SAFELY COUNCIL

Issues periodic reports (7) on the costs of vehicular accidents. Such costs include wage and productivity losses, medical expenses, administrative expenses, motor vehicle damages, and employer costs.

Death $1, 000, 000

Nonfatal disabling injury $ 35, 300

Property damage accident $ 6, 500

BENEFITS OF HIGHWAY IMPROVEMENTS SLEX

are categorized into 2:1. Direct benefits that result

from a reduction in highway user costs

2. indirect benefits, including benefits to adjacent property and to the general public

The most significant highway benefits are those that result from:

reduction in user costs. Decreased operating

costs Higher operating speeds Fewer delays Decreased accident

losses

PRESENT VALUE CONCEPTS

In economic studies it is important to recognize the time value of money. Because of the existence of interest, a quantity of money is worth more now than the prospect of receiving the same quantity of money at some future date.

P= ___F____ (1+I)n

The present worth Ps of a series of uniform annual end-of-period payments A can be determined by the following equation:

Ex.2 The user benefits for a

certain highway are estimated to be a uniform $85,000 per year. Determine the present worth of those benefits assuming an interest rate of 8% and the analysis period of 25 yrs.

Sol’n: Ps=$85, 000 [(1+0.08)^25-1]

[0.08(1.08)^25]

=$907,358

ECONOMIC ANALYSIS TECHNIQUES

Methods used in engineering economy studies include:

benefit-cost ratio net present value comparison of

annual costs determination of

the interest rate at which alternatives are equally attractive.

Formula for benefit-cost ratio:B= _PV(∆ U)__________C PV(∆ I)+PV (∆M)-PV(∆ R)

This formulation which utilizes present values, is now recommended for all highway and transit applications as an approximate indicator of project desirability

BENEFIT COST RATIOSLEX

PV = present value of the indicated amount or series

∆U = User benefits ∆M = increase in annual

maintenance, operating and administrative cost due to the investment

∆R = increase in residual value due to the project at end of project life

∆I = increased investment costs due to the project

NET PRESENT VALUE METHOD

-is defined as the difference between the present values of the benefits from the project and the costs of developing the project. It can be computed as follows:

NPV=PV(∆U)+PV(∆R)-PV(∆I)-PV(∆M)

NPV>0 , THE PROJECT MAY BE ACCEPTED

MEASUREMENT OF USER BENEFITS

The unit highway user cost for a given section of highway HU expressed in dollars per thousand Vehicles is the sum of the Basic section costs, Accident costs and Delay costs

HU=(B+A)L+T+D

Where: B=basic section costs,

consisting of the unit cost (time value and vehicle running costs)

A=unit accident costs in the analysis section

L=analysis section length in miles

T=transition costs D=additional unit time and

running costs caused by delays at intersections, and traffic signals, stop signs, or other traffic control devices.

THE FOLLOWING TRAFFIC AND SIGNALIZATION PARAMETERS FOR THE INTERSECTION BEING STUDIED:NLEX

1. Green-to-cycle time ratio is the ratio of effective green time of the signal to the cycle length of the signal both expressed in the same unit of time.

2. Saturation flows- the approach volume in vehicles per hour of green that is found for the intersection when the load factor is 1.0 and the appropriate adjustment factors are applied.

3. Capacity- the highway capacity manual is used, capacity is the service volume of the approach at a load factor of 1.0.

4. Degree of Saturation-the ratio of the volume of traffic approaching the intersection to the capacity of the intersection in the same units.

5. Approach speed- also termed “midblock speed” this is the average running speed at which the signalized intersection approached by the vehicle stream.

.

COST AND BENEFITS OF BUS TRANSIT IMPROVEMENTS

In economic analyses involving bus transit the user benefits should include reductions in :

Highway user costs

Bus user costs Out-of-pocket

costs

ONE-WAY TRAFFIC VERSUS TWO-WAY TRAFFIC

The costs given by the highway user nomographs relate to one-way traffic on a highway facility. In the usual case where the improvements affect both sides of the roadway and the traffic is balanced in direction over the course of a typical day, the benefits that are calculated from the one-way analysis should be multiplied by 2.

SOCIAL AND ENVIRONMENTAL CONSEQUENCES OF HIGHWAYS

Environmental legislation is important to the highway engineering process not only because of the types of impacts that must be considered in the project development process, but also because it outlines which agencies have approval power of project implementation. The different types of social and environmental impact to be considered by the highway designers.

THE MOST SIGNIFICANT LEGISLATIVE PROVISIONS RELATING TO EVALUATION OF SOCIAL AND ENVIRONMENTAL CONSEQUENCES OF HIGHWAYS:

Department of Transportation Act of 1966

National Environmental Policy Act of 1969

Clean Air Act of 1963 Uniform Relocation Assistance

and Real Property Acquisitions Policies Act of 1970

Federal-Aid Highway Act of 1970

Department of Transportation Act of 1966

declared to be the national policy that a special effort should be made to preserved the natural beauty of the countryside.

National Environmental Policy Act of 1969

declared to be the national policy that the federal government would use all practicable means and measures “to create and maintain conditions under which man and nature can exist in productive harmony.”

Clean Air Act of 1985 encouraged increased state and local programs

for the control of air pollution and development of air quality standard.

Uniform Relocation Assistance and Real Property Acquisitions Policies Act of 1970

an effort to establish uniform treatment of all people affected by public projects financed with federal funds.

Federal-Aid Highway Act of 1970

required the secretary of transportation to publish guidelines designed to ensure that possible adverse economic, social, and environmental effects.

COORDINATION AND PUBLIC INVOLVEMENT

State highway agencies conduct public hearings to afford interested persons an opportunity to participate in the process of determining the need for and the location of highways. For federal-aid highways, one or more public hearings are normally required or proposed projects.

o if substantial amounts of right-of-way are required

o if there is a substantial change in the layout of connecting roads or the facility being improved

o if there is substantial adverse effect on abutting property

o If the property otherwise has significant social, economic, or environmental effects

AT SUCH HEARINGS, A REPRESENTATIVE OF THE STATE HIGHWAY AGENCY EXPLAINS THE:

project’s purpose and need it’s major design features the social, economic and

environmental impacts the measures planned to mitigate

such effects

NOISE STUDIES AND STANDARDS

What is a noise?

Noise – is a sound that is loud, unpleasant, unexpected, or

undesired.

NOISE STUDIES AND STANDARDS

It is suggested that a noise study be prepared during the location stage of all alternative lines under consideration for each highway project. Early in the design process, the present and future uses of land adjacent to the highway should be determined and noise-sensitive areas should be identified.

The prediction of future noise levels is a complex task in which the effects of a large number of parameters should be considered, including traffic volumes and composition, accelerations and speeds, roadway gradients, topography, the presence and types of barriers, and the distance between the highway and the affected area.

AASHTO - AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS 

AASHTO has established standards for evaluation of the impact of highway –generated noise on nearby land uses or activities. The standards provide a basis for the selection of appropriate noise attenuation measures.

THE FOLLOWING EXTERIOR DESIGN NOISE LEVELS ARE RECOMMENDED FOR THE LAND USES AND ACTIVITIES INDICATED:

CATEGORY DESCRIPTION NOISE LEVEL

(Leq)

(dBA) (L10)

ALands 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

57 60

BPicnic areas, recreation areas, playgrounds, active sports areas, parks, residences, motels, hotels, schools, churches, libraries, and hospitals

67 70

C Developed lands, properties, or activities not included in categories A and B above

72 75

D Undeveloped lands -- --

EResidencies, motels, hotels, public meeting rooms, schools, churches, libraries, hospitals, and auditoriums 52 55

NOISE ATTENUATION

Highway engineers can lessen the impact of highway noise on nearby human activities in three general ways:

By providing a buffer zone between the highway and adjacent land activities

By providing the horizontal or vertical alignment of the highway

By providing noise shielding

GENERAL PRINCIPLES FOR NOISE BARRIER DESIGN

1) Barriers should be high enough and long enough to intercept the line of sight between the source and the observer. It is especially important that the barrier be high enough to shield truck exhaust noise. To accomplish this without aesthetic sacrifice, some agencies have constructed combination barriers consisting of an earth berm that supports some type of vertical wall.

GENERAL PRINCIPLES FOR NOISE BARRIER DESIGN

2) To be most effective, barriers should be constructed so as to cast a big sound “shadow.” This generally means that the barrier should be placed close to either the source or the receiver. It should be remembered that noise barriers are fixed objects that, if placed close to the traffic lanes, may be unsafe. For this and other reasons, noise barriers are frequently located near the right-of-way line.

GENERAL PRINCIPLES FOR NOISE BARRIER DESIGN

3) Barriers should be constructed of a dense material, and there should be no air paths through or under the barrier that could constitute noise leaks.

GENERAL PRINCIPLES FOR NOISE BARRIER DESIGN

4) In the interests of community acceptance, barriers should be made as attractive as possible. They should be compatible with local architecture and blend into the forms of the landscape.

HIGHWAY AIR QUALITY

Air pollution may constitute the most serious environmental impact caused by highway transportation. It is a complex problem, and its evaluation and control may require the involvement of highway trained environmental specialists.

AIR POLLUTANTS ARE NATURAL AND MAN-MADE CONTAMINANTS IN THE ATMOSPHERE. THEY MAY BE GROUPED INTO FIVE (5) MAJOR CLASSES:

AIR POLLUTANTS

1) Carbon monoxide (CO)

2) Hydrocarbons (HC) and photochemical oxidants3) Nitrogen oxides (NOx)

4) Particulate matter

5) Sulfur dioxide (SO2)

CONTROL OF HIGHWAY AIR POLLUTION

1) PLANNING 2) DESIGN3) NUMBER OF TRAVEL LANES4) LANE CAPACITY

CONTROL OF HIGHWAY AIR POLLUTION

1) PLANNING Planning for improvements to

highway and transit networks should be coordinated to permit opportunities for transfer between public transit facilities and private automobiles.

CONTROL OF HIGHWAY AIR POLLUTION

2) DESIGNThe physical layout of highway

facilities also affects vehicle emissions. In general, highway design features which reduce congestion and increase operating speeds will also contribute to reduced emissions of air pollutants.

CONTROL OF HIGHWAY AIR POLLUTION

3) NUMBER OF TRAVEL LANESThe number of lanes is an obvious factor that

affects the potential of total pollutants which may be emitted in a given corridor. With a greater number of lanes, the roadway capacity is increased, resulting in a potential for higher traffic densities and therefore higher pollutants emissions.

CONTROL OF HIGHWAY AIR POLLUTION

4) LANE CAPACITYAll roadway lanes are limited in

their ability to accommodate vehicular traffic, and emissions are dependent on the number of vehicles utilizing each lane.

IMPACTS ON WETLANDS

WETLANDS:

Those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted to life in saturated soil conditions. Wetland generally include swamps, marshes, bogs and similar areas.

3 most important factors for defining wetlands:

Type of vegetation

Type of soil

Hydrology

IMPACTS : Groundwater recharge Groundwater discharge Flood flow alteration Sediment stabilization Sediment/toxicant retention Nutrient removal/transformation High export of organic material Wildlife diversity/abundance Aquatic diversity/abundance Recreation Uniqueness/heritage

In addition to an assessment of the impact on these functions, many analysis procedures incorporate what is referred to as “fatal flaw” determination. To give some of what type of impact is considered a fatal flaw in a proposed highway design, following characteristics are considered to have significant levels of impact: (the term in parentheses following each impact characteristics refers to the wetland function affected.)

I. Do any federal or state endangered or threatened species use the wetland area regularly? (uniqueness/heritage)

II. Is the wetland owned by an organized conservation group or public agency for the primary purpose of preservation, ecological enhancement, or low intensity recreation? (uniqueness/heritage)

III. Is the wetland in a statewide listing of historical or archeological sites? (uniqueness/heritage)

Strategies that should be considered by designers:

Wetland replacement:

Wetlands are constructed at other locations to compensate for those impacted at the construction site. The replaced wetland should not necessarily be of the same type as that which was lost. Different types of wetland might, in fact, offer improvements for fish and wildlife or for the control of water quality, flooding, and shore erosion.

WETLAND RESTORATION:

Wetland that are impacted by construction are restored to their original or enhanced function. This is often used to mitigate the impact of temporary construction staging sites or other construction-related locations that will not be permanently part of the highway project itself.

WETLAND ENHANCEMENT:

Wetlands either in the right-of-way or replacement wetlands beyond the project boundaries are designed to improve the value of the wetland over which the original wetland possessed. In most cases, this enhancement relates to fish and wildlife or major improvements to the social values associated with the wetland.

HIGHWAY WETLAND IMPACTS AND POTENTIAL MITIGATION STRATEGIES

Project phase General ecological concerns and/or

impacts

Types of Mitigation and Enhancement Measures

Pre-design Loss of highly productive areas.Loss of oligotrophic water supplies.

Careful selection of corridors and alignments.

Design Changes in water quality .Interruption of fish migration.Enhanced eutrophication.Changes in hydrology.

Design of alignment culverts.Design erosion control measures.Specify provisions in construction contract.

Construction Loss and/or disruption of aquatic species.Loss of aquatic habitat.Loss of water quality in receiving waters.

Implementation of design features.Minimize encroachment and alteration of aquatic habitats.Implementation of erosion control.Careful timing of construction.Careful management of construction camp and site.

Operation and maintenance

Accidental spillage of potential toxicants and irritants. etc.

Implement plans for potential spill. etc.