Case Study:

Portland, Oregon

Overview

Portland, Oregon Trucks in Congested Traffic

This case study illustrates how regional benefits to freight as well as passenger movement can be estimated. Readily available models are used to assess a range of user, economic, and environmental benefits associated with transportation improvements. The methodology benefits from a rich database on freight movements within the metropolitan region.

Interstate 5 (I-5) is a key north-south route for both freight and passenger movement through the Portland, Oregon - Vancouver, Washington metropolitan region. The freeway, which runs from Canada to Mexico, is an important route for long-distance goods movement. With its connections to local industrial centers and intermodal terminals, the freeway is also crucial to the economy of the Portland-Vancouver region.

Given the high levels of congestion on I-5 and the importance of freight movements in this corridor, the Washington and Oregon Departments of Transportation initiated a study of improvements to facilitate freight movement. The study investigated a number of strategies in the I-5 corridor, including:

Fixing hot spots (bottlenecks);
Improving the Columbia River crossing;
Adding more general-purpose freeway capacity;
Adding freight-only freeway capacity; and
Adding more capacity on key freight arterials.

To compare the strategies, user and economic benefits were measured using a combination of a travel model post-processor and an economic simulation model. First, the region's travel demand model was applied in conjunction with FHWA's Surface Transportation Efficiency Analysis Model (STEAM) to compute systemwide user benefits including travel time savings, vehicle operating costs, and accident costs. Benefits were calculated for both freight and passenger traffic. The overall economic benefits to the region were then estimated using the REMI model developed by Regional Economic Models, Inc. The output of the REMI model was used to identify overall impacts on employment, output, and personal income in the Portland region.

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