Emissions decreased by 30 to 37.9 percent and fuel consumption decreased by 32.2 percent on the SR 520 bridge after electronic tolling was deployed.

The Seattle/Lake Washington Corridor Urban Partnership Agreement projects evaluated tolling, technology, transit, and travel demand management strategies to reduce congestion.


Summary Information

In 2006, the U.S. DOT initiated the UPA (Urban Partnership Agreement) program to demonstrate congestion reduction through strategies consisting of combinations of the 4Ts: Tolling, Transit, Telecommuting/TDM, and Technology. The Seattle/LWC UPA projects focused on reducing traffic congestion on SR 520 between I-405 and I-5, a heavily-traveled, east-west commuter route across Lake Washington. The lake separates Seattle from the eastern suburbs (including Bellevue and Redmond). These strategies included tolling all lanes of the SR 520 bridge, adding bus service in the SR 520 corridor, implementing active traffic management systems, and real-time traveler information signs on highways and at transit stops and stations. The suite of projects had a combined benefit-to-cost ratio of 1.76 due to travel time savings and reduced emissions.

The environmental analysis involves multiplying miles of travel by the rate of emissions per mile for each pollutant. The energy analysis is the same except that it uses fuel use rates. Motor vehicle emission rates are modeled with Environmental Protection Agency (EPA) mobile source emissions factor models and are expressed in terms of grams of pollutant per mile of travel and gallons of fuel per mile of travel.


The effect of the tolling on SR 520 was a marked decrease in traffic volumes, emissions, and fuel consumption along SR 520. Emissions decreased by 30 to 37.9 percent and fuel consumption decreased by 32.2 percent on SR 520 after deployment of tolling. Increases were noted on alternative routes, yielding a system-wide reduction of 2.5 to 5.8 percent of emissions and 2.9 percent reduction in fuel consumption.

Values were interpolated (assuming a linear change in values per year) to obtain the monetary benefit of the reduction of four pollutants in each year from 2012 to 2021. Multiplying these values by the amount of pollution reduced, then adjusting the 2007 dollars to 2012 dollars using a discount rate of 7 percent, resulted in a total benefit of $305,515 from VOC, $470,083 from NOx, $426,001 from PM2.5, and $6,075,774 from CO2. Combining the benefits of these individual emissions resulted in a total environmental benefit of $7,448,861.

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Seattle/Lake Washington Corridor Urban Partnership Agreement: National Evaluation Report

Author: Schroeder, Jeremy, et al.

Published By: U.S. Department of Transportation, Research and Innovative Technology Administration, Federal Highway Administration/Federal Transit Administration

Source Date: 12/02/2014

Other Reference Number: FHWA-JPO-14-127


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Urban Partnership Agreement, Congestion Reduction Demonstration, congestion pricing, tolling, congestion reduction, evaluation, emissions, fuel consumption

Benefit ID: 2017-01185