WSDOT Projects

WSDOT highway projects primarily aim to improve the safety and capacity of roadways and extend their use. Almost every project, however, also requires ancillary undertakings to square the project with other public goals, such as clean water requirements or protection of wetlands and endangered species. These other undertakings are the “mitigation” without which a highway project would not happen and its transportation aims would not be realized.

The following case studies present mitigation experience of fourteen actual highway projects. They are designed to illuminate two questions:

1. What is the cost of mitigation for highway projects in Washington State?
2. Are mitigation undertakings and costs reasonable in relation to project objectives?

WSDOT shares the responsibility with regulatory agencies for seeing that project mitigation is reasonable and properly meets legal requirements specified in environmental protection statutes and regulations. The permitting process is a challenging forum in which the byplay of shared responsibility is carried out.

2006 Report Volume 2
Overview (pdf 319 kb)
Methodology (pdf 732 kb)
2006 Project Case Studies & Cost per Lane Mile (pdf 524 kb)

2006 Case Studies

1. I-5 Everett, SR 526 to US 2 HOV (pdf 447 kb)
2. I-405 Kirkland, SR 520 to SR 522 (pdf 1.39 mb)
3. I-5 Tacoma HOV Improvements (pdf 2.43 mb)
4. SR 16 HOV - Union to Jackson (pdf 1.96 mb)
5. I-5 Tukwila HOV - Pierce to Tukwila Stage 2 (pdf 554 kb)
6. SR 270, Pullman to Idaho State Line (pdf 1.86 kb)
7. US 12 Walla Walla - Attalia Vicinity (pdf 751 kb)

Appendix (pdf 71 kb)
2006 Executive Summary (pdf 478 kb)


2003 Report Volume 1
Executive Summary (pdf 1.19 mb)
Project Case Studies Overview (pdf 75 kb)

2003 Case Studies

1. US 2/20/153 Emergency Bridge Scour Repair (pdf 549 kb)
2. SR 20 Bannon Creek to Aeneas Valley Road (pdf 886 kb)
3. I-5 Overcrossing Marvin Road Interchange (pdf 623 kb)
4. US 395 Hillsboro Street Interchange (pdf 434 kb)
5. I-5 Maytown to 93rd Avenue (pdf 504 kb)
6. US 12 McNary Pool to Attalia (pdf 538 kb)
7. SR 510 Martin Way to Pacific Avenue (pdf 640 kb)
8. I-90 Evergreen Road Interchange (pdf 793 kb)
9. SR 14 SE 192nd Avenue Interchange (pdf 660 kb)
10. I-90 Argonne to Sullivan Interstate Widening (pdf 768 kb)
11. SR 18 - 180th to Maple Valley (pdf 1.29 mb)
12. SR 202 - SR 520 to Sahalee Way (pdf 1.51 mb)
13. I-90 Sunset Way Interchange (pdf 1.33 mb)
14. SR 18 Maple Valley to Issaquah Hobart Road (pdf 1.56 mb)

Contact Information
Ken Smith, Deputy State Design Engineer
WSDOT Design Office
PO Box 47329
Olympia, WA 98504-7329
E-mail: smithk@wsdot.wa.gov
Phone: 360 705-7233