Lessons Learned on Congestion Pricing from the Seattle and Atlanta Household Travel Behavior Surveys
The lessons learned described below come from the Volpe demographic household traveler panel survey conducted in Seattle as part of the USDOT sponsored UPA Program evaluation.
The Volpe National Transportation Systems Center conducted a demographic household traveler panel survey in Seattle (as well as another UPA site) as part of the evaluation of the UPA Program (Peirce, Petrella, Puckett, Minnice, & Lappin, 2014). The survey, focused on corridor users assessed changes in route and mode choice, trip timing, origin and destination patterns, and telework that resulted from implementing various pricing related strategies. The survey was also designed to explore changes in travel and tolling related attitudes and equity impacts. Findings included the following lessons learned:
- Pricing influences travel behavior, particularly with respect to route choice and the timing of trips. Even modest toll levels can significantly shift traffic volumes, route and lane choice, modes used, and vehicle occupancies.
- Travelers have a surprising amount of flexibility in their overall levels of travel. Diary data from Seattle showed respondents reduced their use of the priced route, total trips fell 14 percent, VMT decreased 15 percent, and average daily time spent traveling decreased 12 percent.
- Pricing can have a significant impact on route choice. Of the survey respondents, 25 percent of former SR-520 users switched to the I-90 with increased traffic volumes and congestion increased on that alternative route.
- Impacts on mode choice and occupancy depend on the design of the tolling project and the regional context.
- Pricing affects the timing of trips in complex ways. General demand by time-of-day did not change significantly; however, there were small but measurable increases in the share of vehicle trips that occurred during the peak period
- Pricing does not appear to have a noticeable impact on telecommuting. Tolling did not lead to any increase in telecommuting.
- Travelers appreciate improved traffic conditions from variable tolling. Improvements in travel times on the tolled facility are noticed and appreciated by travelers. It led to greater levels of subjective trip satisfaction among SR-520 users.
- Attitudes toward tolling change with direct experience. In Seattle, general attitudes toward tolling shifted in a positive direction after the project was implemented.
- There are demographic differences in responses to tolling, mostly related to income. Although respondents of all income groups used the tolled facilities, the heaviest users were disproportionately from upper-income households.
- Equity impacts can take many forms and present measurement challenges. Seattle’s very small number of low-income households among peak-period users made it difficult to draw firm conclusions about income equity impacts.
Lessons learned lead to the following implications for deployment of congestion pricing strategies:
- Near term shifts in mode or increases in carpool size require programmatic support. Travelers are much more apt to make changes to their number of trips, the timing of those trips, and their choice of route (or lane), than they are to make more fundamental shifts in their mode of travel. For regions contemplating congestion pricing, this is an important consideration. The region may need to conduct additional community outreach and programmatic support to generate larger shifts in transit, carpooling, and telework.
- Make the requirements for using the priced facility as simple and convenient as possible.
- The more public communication, the better. A robust outreach plan, with ongoing and constant public communication, can be a great tool to prepare the public for the new system.
- Agencies should anticipate that pricing will have differential impacts on corridor users. Road pricing creates a set of “winners” and “losers” in the region.
- Strong community and civic engagement supports a positive response to road pricing.
- Regional factors influence public attitudes toward tolling.