The purpose and need statement (pdf 133 kb) is an essential part of the environmental process. It explains why the project is being proposed and why it is a worthwhile investment of time and money. The purpose and need statement also helps provide context and criteria for developing a range of possible alternatives, and eventually the selection of a preferred alternative.
Purpose of the I-90 Tolling Project
The purpose of Interstate 90 tolling is to raise revenue for substantial transportation improvements in the Cross-Lake Washington Corridor and to help alleviate congestion on I-90 between I-5 and I-405.
Need for the I-90 Tolling Project
The movement of people and goods needs to be improved on both the I-90 corridor and the overall Cross-Lake Washington corridor. The following sections describe current and forecast future conditions in the corridor and demonstrate the need for tolling and congestion management.
- Raise revenue for Cross-Lake Washington Corridor Improvements - The tolling component of this project is needed to fund transportation improvements in the Cross-Lake Washington Corridor. Revenues generated from tolling I-90 will make a major contribution for the portion of the SR 520 Bridge Replacement and HOV Program that is currently unfunded.
- Alleviate congestion on the I-90 Corridor - Current travel conditions in the I-90 corridor can be extremely congested, particularly during rush hour. With variable rate tolling on I-90 some travelers will likely make their trips outside of the peak periods to avoid paying higher tolls, which would redistribute some trips on the I-90 corridor and help reduce peak period congestion.
- Accommodate regional growth - Long-term forecasts for growth in the region show continued steady increases in population and employment. Regional forecasts anticipate the population of King County to increase from fewer than 2 million in 2010 to over 2.56 million in 2040 while jobs increase from about 1.2 million to about 1.8 million jobs for the same time period. Much of this growth is expected to occur on either side of Lake Washington. By reducing congestion during peak periods tolling on I-90 may improve overall throughput.
- Provide reliable travel conditions in the I-90 Corridor - Two of the most substantial outcomes of severely congested traffic conditions are increased travel time and reduced reliability. With heavily congested conditions, the difference in travel times between non-peak periods and peak periods increases. The heavily congested conditions also mean it is more difficult for motorists to maneuver and change lanes, which can result in crashes or near misses between vehicles.