Find Posts By Topic

3 C’s Help Mercer traffic flow and construction impacts diminish

As 2014 draws to a close, construction in Seattle presses on with some help from the three C’s: Coordination, Communication, and Collaboration. It’s been another boom year, following the 2013 surge—a bounce back from the recession.
With the 2013 construction surge came the new Access Seattle Initiative to keep businesses thriving, travelers moving, and construction coordinated during peak building periods. Part of that plan is the Construction Hub Coordination Program, targeting areas of concentrated construction (hubs) to holistically assess impacts of all public and private projects. More hubs are expected in 2015.



Looking east at westbound Mercer traffic, including southbound left turns onto 5th Ave. N

What’s made the difference since the Construction Hub Program’s inception is good communication and collaboration. A great example of that is the recent Mercer Corridor coordination effort.


As Mercer Corridor construction takes the two-way concept all the way from I-5 to 5th Ave. N (completion anticipated mid-2015) travelers continue dealing with regular traffic alterations. This fall the South Lake Union Community Council (SLUCC) gave a list of concerns to the construction hub team, including congestion along Mercer.


“It’s the Community Council’s role to listen to community members regarding what they’re seeing and looking to improve; then to work in partnership with city departments to bring those concerns and visions together,” said SLUCC President Mike McQuaid. “To no surprise, one thing we consistently heard about is Mercer traffic back-ups.”



Crews adjusting Mercer/5th Ave. N signal to prepare for final intersection configuration: a 3rd eastbound lane and 2 separate westbound left-turn lanes

McQuaid worked with the construction hub team to underscore community priorities and follow up on progress. SDOT acted quickly, McQuaid commented, to address the issues raised. Options to comprehensively improve Mercer traffic flow were assessed and added to signal adjustment plans already in the works. The following changes were made:

  •  5th Ave. N and Mercer St. signal reconfigured to run East-West Mercer traffic concurrently, improving efficiency and reducing delays compared to the previous split-phase operation (this was done in concert with the Mercer Project’s opening of a third eastbound lane November 16, 2014)
  • Queen Anne Ave. N and Roy St. signal phasing modified, resolving a problem with vehicle blockage of the Queen Anne Ave. N crosswalk
  • Fairview Ave. N and Mercer St. southbound left turn time extended
  • Lower Queen Anne area Rapid Ride “D” Line transit given signal priority
  • Seattle Center special event signal timing plan implemented to coincide with large events (with positive reception from the Seattle Center event timing signal change, SDOT is also planning to implement a large event signal timing plan near McCaw Hall)


As the Construction Hub Coordination Program strives to limit construction impacts, Access Seattle is always looking at ways to keep a growing Seattle mobile and thriving. By no coincidence, community organizations do the same.


During SLU traffic discussions with SDOT this summer, the Queen Anne Community Council, South Lake Union Chamber of Commerce and the South Lake Union Community Council asked about better technology for traffic flow along Mercer. SDOT had plans for something called adaptive signal controllers (ASC), dynamic signals that automatically adjust in real-time based on current traffic conditions. Seattle is a national leader in adopting this state-of-the art technology to move cars, busses, bikes and pedestrians efficiently. However, there was only enough funding to install base technology that could later receive ASC.


The neighborhood and business organizations then talked with Seattle City Council and Transportation Committee Chair Tom Rasmussen about funding Mercer adaptive signal controllers. SDOT joined, highlighting that the supportive infrastructure was already in place so funding to complete phase one/Mercer Corridor (shown by red dots in map below) would be about $1 million. With SDOT/community collaboration supporting the need, City Council said yes to bridging the funding gap to make ASC implementation a reality.

Traffic Responsive

“In my opinion this is how it should work,” said McQuaid. “Community councils serve a very important role helping our city function and move forward. We help leaders in city departments by sharing neighborhood interests so they can in turn help the community. The Mercer signal effort is an example of that work done in the right way.”


The adaptive signal controllers will be installed starting in 2015 and will get finalized in 2016 . They’re expected to make a significant improvement moving traffic through the Mercer Corridor, in and out of South Lake Union and the downtown core.


So the final story is the three Cs of Coordination, Communication and Collaboration bringing solutions to communities. That’s a story Access Seattle and the Construction Hub Coordination Program want to tell over and over again…for every Seattle community in need.


Covering the entire city is the Construction Hub team of five in-office project coordinators/analysts and two on-site coordinators (one more added in 2015 with budget approval) all with SDOT, and a business liaison with the Office of Economic Development. The small but nimble group is dedicated, already making strides in Capitol Hill, West Seattle and South Lake Union. If you have questions about construction in your neighborhood, contact the Construction Hub Coordination Program team at