I-5 - Tumwater to Mounts Road Corridor Study

I-5 Tumwater to Mounts Road Study Area Map

Study News

  • WSDOT received an additional 1,300 responses in the follow-up survey that concluded on March 31st. This brings the total number of survey responses to roughly 4,600. Thank you to everyone who provided input. The agency will use your responses to refine the study's overarching goals, refine ideas for improving the transportation system, and evaluating the modeling results. WSDOT is working on a brief summary to share with the public on the results from the surveys.

Study Purpose

WSDOT is studying transportation system performance on I-5 through Tumwater, Olympia and Lacey in collaboration with local partners. The study area extends from the SR 121/93rd Avenue SE/Tilley Road Interchange in Tumwater to Mounts Road just east of the Nisqually River. This segment of highway travels through Tumwater, Olympia and Lacey and is a major freight and commuter corridor. This section of I-5 experiences congestion, recurring delay, and unreliable travel times. Multiple factors contribute to these issues such as traffic volumes and merging at interchanges. WSDOT's goal is to recommend a set of performance-based strategies to achieve the following outcomes in the study area over the next 20 years:

  • Improve travel times and make them more predictable
  • Increase the ability of I-5 to efficiently and equitably move people and goods
  • Improve access to industrial and commercial areas and job sites
  • Protect and enhance the environment including reducing the transportation-related impact on wildlife habitat in the Nisqually River delta
  • Improve the transportation system's ability to operate during and recover from disruptions such as traffic incidents

The End Result

WSDOT will publish a report at the end of the study that will recommend strategies to improve system performance and manage congestion in the study area. These recommendations will be based on data and analysis from the study and local community input.


Fall 2018

  • Local government and community engagement
  • Data collection and analysis, develop improvement strategies

Winter 2018

  • Continued local government and community engagement
  • Refine and finalize improvement strategies

Spring 2019

  • Draft report
  • Online and in-person public meetings to review and comment on recommended strategies

Winter 2019

  • Publish final report


The study is funded through state and local appropriations totaling $550,000.


Dennis Engel, Multimodal Planning Manager

Karen Parkhurst, TRPC Programs & Policy Director

Bradley Bobbitt, Study Staff