Title: MODELING SOAK-TIME DISTRIBUTION OF TRIPS FOR MOBILE SOURCE EMISSIONS FORECASTING: TECHNIQUES

The soak-time of vehicle trip starts is defined as the duration of time in which the vehicle’s engine is not operating and that precedes a successful vehicle start. The temporal distribution of the soak-time in an area is an important determinant of area-wide mobile source emissions. In the current paper, we formulate and implement a methodology for modeling soak-time durations. The methodology involves estimation of models using vehicle trip data from household travel surveys and supplementary zonal demographic/land-use data. The effectiveness of the methodology lies in its easy application at the traffic zonal level within a metropolitan region to obtain zone-specific soak-time distributions by time-of-day and origin activity purpose. The methodology is applied to estimate soak-time duration models for the Dallas-Fort Worth area of Texas.