75C - PH - BRISTOL EIR FROM WARNER TO ST. ANDREW

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Long -term impacts are those associated with the change in usage of Bristol Street that will result from the roadway widening. Emission projections can be made for current conditions (1987) and future design year conditions (2006) by multiplying anticipated motor vehicle usage rates with and without the project by the appropriate emission factors. The emission factors used were taken from the ARB EMFAC6D model which adjusts the EPA "Mobile Source Emission Factors" to reflect the more stringent emission requirements of California vehicles. Vehicle miles of travel (VMT) and average route speeds are typically the basis for estimating the change in air pollutant emissions associated with a roadway improvement project. Traffic data provided by Willdan Associates representing current and future conditions indicate changes in average route speeds but no change in design year VMT values with and without the project. The traffic prediction model, upon which the assessment of air quality impacts was based, assumed that future traffic volumes along Bristol Street would be approximately the same, with or without the proposed improvements. The proposed improvements will expand the traffic carrying capacity and efficiency of Bristol Street and, for a short period of time, commuters may experiment with the improved Bristol Street as an alternate north /south route. Such changes in normal commuting patterns are possible, but cannot be quantified with any acceptable level of accuracy, and may, in fact, not occur. It is acknowledged that, should commuters temporarily or even permanently alter their normal north /south travel to drive greater distances in order to use an improved Bristol Street, total VMT would increase, and traffic speeds may not increase as much as predicted. These effects could alter the future air quality conditions. Table 14 provides the air pollutant emission projections anticipated for existing conditions and future conditions in the design year (2006) with and without the project. As shown therein, there will be a decrease in future carbon monoxide emissions of 3,666 pounds /day with versus without the project in 2006. There will also be a decrease in hydrocarbon emissions with the project (376 pounds /day in 2006). There will be an increase in nitrogen dioxide emission of S pounds /day in 2006. There will be no change in the emissions of sulfur dioxides and particulates with versus without the project. The widening of Bristol Street will relieve congestion which will lead to slightly higher speeds and shorter travel times. The increase in speed will cause a significant reduction of carbon monoxide and total hydrocarbon pollutant emissions from the vehicles using the road. However, higher speeds increase emissions of oxides of nitrogen from each vehicle on the roadway. IV -11 75C -146