Demand Forecasting Model for Park-and-Ride Lots in King County, Washington

As the demand for using park-and-ride lots grows, the need to accurately forecast these trips also grows. Initially, demand for park-and-ride lots was forecast using a technique that identified the draw area for each lot and estimated demand without regard to capacity. These were simplifying assumptions that are no longer appropriate with respect to current demand for park-and-ride lots. In King County, Washington, the 12 largest park-and-ride lots are currently operating at 95 percent utilization. According to a recent park-and-ride lot survey in King County, there is significant latent demand for using lots that are full. The analysis of demand for parking in park-and-ride lots in King County was developed as part of the Washington State Department of Transportation Public/Private Partnership Program for the Park-and-Ride Capacity Enhancement Project. There were 17 park-and-ride lots considered for capacity enhancement. The approach to evaluate park-and-ride lot demand uses a technique to identify intermediate stop choices, such as park-and-ride lots, as part of the overall modal choice. User and nonuser surveys were evaluated to identify the importance of specific variables, such as security or amenities. A combination of the survey results and an application of the demand forecasting model were used to estimate shifts in demand for parking from increased capacity and user fees. Several different user fees were tested and compared with stated preference results from the user and nonuser surveys. The project resulted in significantly different demand for park and ride than previous modeling efforts because of the impact of lot capacity and effects of user fees.