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97 <br />Extended Vehicle Idling <br />® Introduction <br />Item (xi) of Section 108 (f) of the 1990 amended Clean Air Act defines "programs to <br />control extended idling of vehicles" as a candidate transportation control measure. The <br />Idea is that vehicular emissions fan be reduced by eliminating vehicle idling, either by <br />turning the engine off while the vehicle is stopped or by limiting the periods of time in <br />which a vehicle must be stopped and idling. One method of reducing vehicle idle time <br />is through the use of traffic flow improvement techniques, and these are discussed in the <br />corresponding chapter of these information documents. This chapter addresses two <br />other sources of extended idling of vehicles: <br />• Passenger vehicles using drive - through facilities, such as those existing at banks and <br />fast food restaurants, where the vehicle is kept idling during the service period. <br />• Hea-.7 -duty vehicles that are not in use and are kept idling rather thai being shut <br />off, such as buses that are kept idling at layover points or trucks.that are left to idle <br />while being loaded or unloaded. <br />The tradeoff between idling emissions and hot-start emissions by vehicles of a particular <br />type depends on a number of factors including the age of the vehicle, the type of control <br />equipment used, the type of fuel used, the pollutant of interest, and the ambient tem- <br />perature. For ekample, catalytic controls work well in the idle mode, so that idle emis- <br />sions from newer vehicles are far less of a problem then from older, non - catalyst <br />equipped automobiles. It is difficult, therefore, to develop a single transferable number <br />that represents the maximum desired idling time,. The. following is an.analysis for one <br />urban area which indicates the factors which should be considered. <br />in preparing the 1982 Revised Air Quality Management Plan (AQMP) for the South • <br />Coast Air Basin, a strategy for reducing idling emissions by restriction or elimination of <br />drive - through facilities was considered (3). An emissions analysis of drive - through <br />facilities was done by comparing the emissions from idling with those from a hot <br />start /hot soak cycle, which would represent a person parking, carrying out a business <br />transaction within an hour, restarting the car, and leaving. The results are summarized <br />in Table 1. <br />According to this analysis, for CO a car could idle for 6 minutes before it would generate <br />the same emissions as when it was restarted. The equivalent idling times are even <br />greater foi• HC and NOx. Based on this analysis, it was concluded that the banning.of <br />drive - through fadlities would be counter- productive. <br />Extarded Veh7cfe1dt8rg t <br />