A work group tasked with examining alternatives to the Sound Transit-proposed layout for a bus station on Mercer Island reported its findings to the city council last week.

At an Aug. 20 city council meeting, public works director Jason Kintner presented two proposed alternatives to the council, one of which was already shot down. Residents had expressed concerns about loss of intersection capacity, pedestrian volume and safety, and crime and public safety.

When the Sound Transit light rail station opens on Mercer Island in 2023, bus traffic heading to Seattle from the Eastside will see riders eventually boarding the light rail to make their way into the city. The proposed transfer station is slated to be built on the north side of I-90 with a roundabout for the buses on 77th Avenue Southeast.

However, that means buses will need to turn around somewhere on the island before heading back to the Eastside.

Previous reports from Sound Transit showed four possible routes for a bus turnaround. Some options charted routes through the city’s town center. Residents had expressed concerns about buses idling and creating pollution.

One alternative proposed by the working group was known as the 80th Avenue Hybrid option, where buses would get off at the 80th Avenue Southeast off-ramp and head into the bus intercept area from there. That would keep buses out of the downtown core, but both Sound Transit and King County Metro said the plan had flaws, including turns that are too tight for the buses and not enough space for bus layovers and pedestrians.

Another option would be to build a double roundabout, one at 80th Avenue Southeast and Southeast 27th Street. However, the costs of that option could be more than $5 million and Southeast 27th Street would need to be realigned. At the same time, Sound Transit is still moving ahead with its planning, meaning time is running out for Mercer Island to suggest changes to the plan.

A roundabout at 77th Avenue Southeast is already planned by Sound Transit as part of a settlement agreement reached in 2017. The agreement was meant to offset impacts of light rail construction and operation.

The roundabout impacted private property owners and adjacent homes, but Sound Transit agreed to manage and pay for that. If the city chose to develop a second roundabout, it would be on the city’s dime.

Sound Transit’s buildout will create a regional transportation network with light rail stations from SeaTac to Issaquah. Mercer Island could have between 12 to 20 buses entering it during morning commutes, with the type of buses to be decided upon in 2021.