CE 341 Transportation Planning Environmental Impact of Transportation Projects

 Governmental regulations require an environmental impact Assessment (EIA). The EIA must includes studies of the environmental, social and economic impact of the proposed projects.  Many components of EIA studies fall beyond the usual practice of transportation and traffic engineers and should be conducted by a specialist in the specific area.

EIA DEFINITION - Early at the design phase of Projects. -Typical Projects Requiring EIA are : Waste management & disposal (solid, medical) Infrastructure (roads, highways, tunnels, bridges) Water supply & irrigation (dams, canals, lakes) Wastewater collection & disposal Exploitation of natural resources (quarries, mines) Coastal zone developments and Industrial activities

EIA Content  A comprehensive EIA on a -large project may include the following: -Natural resources -Relocation of individuals and families -Air quality studies -Noise impacts -Wet lands and coastal zones -Water quality issues -Flood hazard studies -Social and economic impact -Construction effects

EIA EVOLUTION  Early 1970s :initial development 1970s to 1980s: trend to integration1970s to 1980s: trend to integration Mid to late 1980s: cumulative effects & policy integrationMid to late 1980s: cumulative effects & policy integration Mid 1990s: towards sustainabilityMid 1990s: towards sustainability (Strategic Environmental Assessment )  World Bank, Arab and other international funding agencies introduce EIA policies within loan agreements.

Noise Impact Studies  Determine the additional noise generated by the use of transportation systems in the community.  The characteristics of environmental noise that are of particular concern are :  Magnitude of the sound  Frequency of the sound  Temporal distribution of the sound  Time variance of the sound

Intensity  Intensity decreases inversely as the square of the distance from a point source generating a fixed power

Noise Level Noise Level   Noise: undesirable or unwanted sound   Level measurement: decibel

Temporal Distribution and Time Variance -L50 is the sound level exceeded 50%of the time (i.e.,the median sound level ). - L10 level is the sound level exceeded 10 % of the time.

Design Standards for Noise Levels Land use Design Noise Level-L10 Exterior or Interior Lands on which serenity and quiet are of extraordinary significance 60 dB (A) Exterior Picnic areas, recreational, parks, residences, hotels, schools, hospitals, libraries 70 dB (A) Exterior Other developed lands, properties and activities 75 dB (A) Exterior Undeveloped land No limit Residences, hotels, meeting rooms, schools, libraries, hospitals 55 dB (A) Interior

Ambient Noise Levels  Ambient noise is the total noise composed of all natural and human –made noise sources considered as part of the acoustical environment of the general area  Ambient measurement times should coincide with peak-hour traffic volumes for key sites. Under some circumstances a 24-hour study period may be desirable.  Noise can be measured directly using a sound level meter (SLM) or with a tape recorder and statistical analyzer.  The noise source for automobiles and light trucks is considered to be at ground level because the primary radiated noise comes from the tires and pavement.

Mitigation Measures  From the contour lines, noise- sensitive locations can be identified. Especially critical noise- sensitive sites such as schools, hospitals, and social welfare must be identified for ambient measurements.  Possible mitigation options include changes in location (realignment) and geometry (gradient, elevation, tunnel) and the use of road-side barriers (walls, trees, or other shielding techniques, pavement (smoother aggregates).

Measures to Reduce Noise  Depressed Highway  Noise Barriers

AIR Pollution

Major Pollutants The major direct pollutant species present in emissions are: 1- Carbon monoxide (CO): a product of incomplete burning of fuel. 2- Hydrocarbons (HC): incomplete burning or evaporated fuel or solvents, produced by mobile sources. 3- Nitrogen oxides (NO x ): products of high- compression internal combustion engines. 4- Sulfur oxides (SO x ): product of the burning of sulfur- rich fossil fuel, particularly coal with minor emissions from motor vehicles. 5- Particulates: mostly carbon particles much like soot. 6- Lead: the result of burning leaded gasoline.

Measuring Emissions: Example from Tehran

Automobile Emission Characteristics.  The nature and concentration of those emissions vary with: -type of engine- mode of operation -fuel composition- atmospheric conditions -presence and working condition of emission control devices, and -engine tuning.  The mode of operation determines the air \fuel ratio, which is a key factor determining the rate of emission output.  The completeness of combustion, which also affects emissions, is relatively low when decelerating and idling.

Air Quality Impact Studies Commonly conducted analysis for highway or an airport projects. The Steps are: 1-Projecting the amount of traffic expected to result from the project. 2- Calculating the quantity of pollutants that will be emitted by the project traffic. 3-Estimating the resultant concentration of the pollutants of interest for a particular receptor site, using a dispersion model or some other analysis tool 4-Adding the traffic- generated pollutant concentration to an expected back-ground concentration generated by other pollutant sources. 5-Comparing the results to the ambient standard for various alternatives.

Natural Resources Endangered  Ground water  Green cover and forests

Mitigation Measures  Slope stabilization to protect buildings  Slope planting  Deserted unused areas

Water Courses

Aesthetics  Pedestrians bridge  Bridges  Guardrail  Noise breaker

Mitigation Measures: Retaining Walls