PORT OF SEATTLE 
MEMORANDUM 

COMMISSION AGENDA             Item No.      7a 
Date of Meeting  May 10, 2011 
DATE:    May 5, 2011 
TO:      Tay Yoshitani, Chief Executive Officer 
FROM:    Patricia Akiyama, Director, External Affairs 
Mike Merritt, Local Government Affairs Manager 
Geri Poor, Regional Transportation Manager 
Dan Burke, Regional Transportation Lead Planner 

SUBJECT:  City of Seattle West Mercer Place Study Update 

BRIEFING OUTLINE: 
At the May 10, 2011, Commission meeting, the City of Seattle will present the findings of the
West Mercer Place Study. The Study looks at potential infrastructure improvements for West
Mercer Place, and their impacts on vehicle travel time in this corridor. The team will also
respond to Port Commission questions raised at the November 2, 2010, Commission meeting
(see Previous Commission Review below). 
BACKGROUND: 
The Mercer Corridor is a critical link in the overall Alaskan Way Viaduct Replacement Program.
The Corridor's two segments, Mercer East and Mercer West, are designed by the City as a twoway
street that will provide east/west access between I-5, the Viaduct North Portal, and Elliott
Avenue West, serving Terminal 91 and the Ballard-Interbay Manufacturing and Industrial
Center. 
Mercer East is in the first year of a three-year construction program that will widen Mercer Street
to six lanes from Dexter Avenue North eastwardly to the I-5 ramps at Fairview Avenue. Mercer
West, currently under design, runs from Dexter Avenue North westwardly to Elliott Avenue
West. As part of Mercer West, Mercer Street will be widened to six lanes from Dexter Avenue
North to Fifth Avenue North under SR 99, which the Port desires for freight mobility. From Fifth
Avenue North to Fifth Avenue West, Mercer West is expected to be completed by reconfiguring
and restriping the existing roadway. Potential improvements to West Mercer Place are being
determined through the West Mercer Place Study.

COMMISSION AGENDA 
T. Yoshitani, Chief Executive Officer 
May 5, 2011 
Page 2 of 2 

SDOT began the West Mercer Place Study in the Fall of 2010 and included Port staff input into
the study review. SDOT staff presented preliminary findings of the study to Port staff in January
2011. Following the review, SDOT staff completed additional analysis and began presenting
updated findings to project stakeholders in March, 2011. The City expects to choose a preferred
alternative in mid-to-late May. 
OTHER DOCUMENTS ASSOCIATED WITH THIS REQUEST: 
SDOT PowerPoint 
PREVIOUS COMMISSION REVIEW: 
On November 2, 2010, the Alaskan Way Viaduct Team updated the Port Commission on the
Alaskan Way Viaduct and Seawall Replacement Program. At the meeting, Commissioners
asked questions about the City of Seattle's West Mercer Place project. Ron Paananen of
WSDOT and Bob Powers of the City of Seattle said the West Mercer Place Study is underway
and the team would be available toward the end of April 2011 to update the Commission. 
Specifically, the Commission asked that the following be addressed in the West Mercer Place
Study: 
Traffic model runs would include a sensitivity analysis of the potential for higher density
development and related traffic impacts for the Terminal 91 Uplands; 
A dual-lane uphill option would receive equal analysis and consideration as the single-
lane option on West Mercer Place; 
Traffic model runs would include analysis in the Elliott/15th Avenue corridor all the way
to Fisherman's Terminal; and 
Impacts of slow-moving freight on Mercer Place must be considered. 






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