Design & operation details for proposed Mercer Island Transit Exchange

March 25, 2019 | by Scott Strandberg

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Proposed Mercer Island Transit Interchange Operations

With construction well underway on Mercer Island’s future light rail station, the City and community members now have the opportunity to evaluate the design configuration and operation details of the proposed Mercer Island Transit Exchange, which will integrate bus operations with the light rail station. A key feature of this exchange is a roundabout to be located at North Mercer Way and 77th Avenue SE.

At the City Council meeting on Tuesday, March 19th, Sound Transit provided the latest information regarding the construction of the East Link light rail line, including goals and objectives, as well as steps taken to satisfy Sound Transit’s settlement agreement with the City of Mercer Island.

In October 2017, the Mercer Island City Council accepted Sound Transit’s offer of over $10 million to mitigate the effects of light rail construction. This settlement included compensation for altering traffic on Mercer Island, especially the loss of entrance and exit ramps from Island Crest Way, the four-lane road that runs from the north end of the island through Pioneer Park on the south end.

At last week’s Council meeting, Sound Transit gave a presentation detailing their objectives for the transit exchange, as well as some information regarding the key components of the settlement with the City. Among the goals cited by Sound Transit were the prioritization of convenient transfers through the Mercer Island exchange, along with minimizing property impacts and maximizing benefits to the community.

The presentation also included some key components to successfully realizing those goals, like the limiting of bus routes to not exceed the current volume of bus traffic on the Island. Other highlighted components were the proposed development of a roundabout at North Mercer Way and 77th Avenue Southeast, which would allow buses to turn around and head back east after dropping off riders, which would help prevent regional buses being routed through Mercer Island Town Center.

Proposed 77th Avenue SE Roundabout—Conceptual Design

Finally, Sound Transit touched on some refinements to the original settlement agreement, including the implementation of public transit layover limits to prevent buses from spending excessive time idling or otherwise occupying Mercer Island streets unnecessarily. The other refinements discussed were the allowance of transit operations on the north side of North Mercer Way near the impending light rail station, and the potential for an Island-exclusive bus stop on 80th Avenue Southeast.

Sound Transit’s presentation represented the latest developments from their Mercer Island Transit Interchange Operational and Configuration Study, which was implemented to evaluate the impact of multimodal transportation between the bus and rail systems on Mercer Island. According to information provided by the City Council at the March 19th meeting, the opening of the East Link light rail will coincide with a decrease in bus routes from off-island locations.

Following the study session at the City Council meeting, Mercer Island residents can voice their concerns about the project through a portal on the Let’s Talk Mercer Island website. Messages received through this portal will be considered for discussion at future City Council meetings pertaining to the East Link development.

Related Reading:  “Sound Transit Unveils Bus Turnaround Options for Mercer Island” [Mercer Island Reporter]