In 2008, gas prices rose to $4.40 per gallon and then came down to $2.50 in the Seattle metropolitan region. As a result, PSRC’s Transportation Policy Board and Pricing Task Force asked a series of questions related to the potential travel and economic impacts of rising and falling gas prices. PSRC staff completed sensitivity tests to understand the potential impacts on travel, trip lengths, modal choices, vehicle miles traveled, emissions, and user benefits and costs.

The sensitivity tests were based on analysis completed by ECONorthwest to forecast vehicle operating expenses for autos and trucks in Puget Sound, incorporating short and long run sensitivity to fuel cost changes. The vehicle operating costs (fuel and maintenance) accounted for the interaction between fuel costs and fleet efficiency and currently adopted regulations on fuel efficiency. The analysis produced a base, high, and low forecast of vehicle operating cost for autos and trucks in 2030.

The sensitivity tests were applied to several of the future year alternatives developed for the regional transportation plan (Transportation 2040). Benefits and costs are compared to each base case (i.e. baseline, alternative 1 or alternative 5 as appropriate) so that the impacts of the changes in fuel cost are isolated. The results indicated that with limited tolling in the region, higher gas prices have a positive net benefit to users and lower gas prices have a negative net benefit to users. With significant tolling in place (as in Alternative 5 with full network tolling), lower or higher gas prices have a more limited impact on user benefits probably because there are already very large user benefits from the regional tolling policy.