Travel Demand Forecasting Analysis Challenges Supporting Washington State Ferries' Long-Range Plan Development

Document Type

Journal Article

Publication Date


Subject Area

mode - ferry, place - north america, ridership - modelling, planning - travel demand management


ferry ridership, long range plan (LRP), Washington, forecasting


Ferry ridership modeling and forecasting analyses were performed to support the long-range plan (LRP) recently undertaken by the Washington State Department of Transportation Ferries Division (WSF). The LRP was developed in response to specific legislative direction. The ferry ridership forecasting analyses posed numerous challenges. In particular, the legislation directed WSF to improve its travel demand forecasting approach to ensure its plans were based on the best projections of future needs. To be able to address adequately the travel demand forecasting requirements called out in the legislation ("Ferry Bill"), a technical work group was formed that included expertise from both public agencies and consulting firms. The group met regularly over approximately 1 1/2 years to review and provide valuable feedback on the ridership forecasting procedures and results. The primary planning tool used to perform ferry ridership forecasting analysis was the WSF travel forecasting (Emme) model. The WSF travel forecasting model relies on an incremental method and produces route-level ferry ridership by boarding method and mode of access and egress. The model's capabilities were supplemented by performing additional analyses, including development of (a) expansion factors to produce annual ridership, (b) growth projection factors specific to the recreational travel segment, and (c) fare elasticities by time-of-day using stated preference survey data. Ridership forecasting analyses were performed for a baseline and a range of scenarios that also included pursuit of pricing strategies.


Permission to publish the abstract has been given by TRB, copyright remains with them.