Washington State Ferries’ Travel Demand Model Development and Forecasting Analysis Programs: A 10-Year Perspective

Abstract

Recent Washington State Ferries (WSF) origin–destination travel survey data collection and model development activities are described. WSF performed similar activities in 1993. The lessons learned from the initial project helped to develop a better survey design and sampling plan. The overall survey response rate was 37%, about 28% higher than the response rate for the 1993 travel survey. The improved survey design and sampling plan also provided a richer data platform from which to establish more representative observed baseline ferry travel patterns, by boarding method and access and egress mode combinations. Compared with 1993, the 1999 travel survey results reflect a significant increase in the systemwide use of transit for access to and egress from ferry terminals. This increase was primarily attributed to improved transit service, timed ferry-bus connections, and ferry-bus passes implemented by Kitsap Transit and other transit agencies. In addition to the 1999 travel survey, WSF conducted a stated preference survey. The combined data from these two surveys provided information on ferry users’ revealed and stated preferences, which allowed a more rigorous statistical mode and route choice estimation analysis to be performed. This analysis helped develop a more robust and internally consistent model, as reflected in model performance. For walk-on and automobile-boarding passengers, the updated WSF model has produced more accurate route-level validation results than the previous model. The results from the model estimation and validation analyses are presented. Specific improvements made in the updated model are highlighted.