Plan a Trail Outing Around Mercer Island Station and the Mountains to Sound Greenway
A trail outing with a train journey starts with two plans: where you want to run, and how you will travel before and afterward. Mercer Island's I-90 corridor brings light rail and park trails into the same planning picture. Use station amenities, the city's park information, and Bellevue's construction details to decide on an outing. Choose the distance and the return journey together, rather than assuming every part of the regional corridor is ready for an uninterrupted run.
Sound Transit announced the opening of the Crosslake Connection on March 28, 2026. The connection completed the 2 Line and carried light rail passengers across a floating bridge for the first time. Its final seven-mile segment included Mercer Island and Judkins Park stations and connected to the 1 Line at International District/Chinatown Station.
At the opening, Sound Transit described a Link network spanning 63 miles with 50 stations. For a running plan, the useful question is which station fits your start and finish. Identify both parts of the journey before choosing a one-way outing, and check the travel arrangements for the day you intend to go. A train journey can be part of the plan without committing you to a particular running distance.
Sound Transit's Mercer Island Station information states that the station has no public restrooms for passengers. Its bike facilities include racks for 50 bikes, 24 individual BikeLink lockers available on demand, and a bike room with capacity for 20 bikes. Plan restroom needs separately from the station stop; the city lists restrooms among Aubrey Davis Park's amenities.
For a train-first plan, choose the station where you will arrive, confirm your route to the trail, and decide how the run will end. For a run-first plan, identify the finish station and the way you will reach it from the trail. Both approaches call for a clear connection between the route and the return journey.
Write down a shorter alternative as well. If the planned trail access does not work for the day, a defined turnaround or a different finish is easier to consider than an improvised extension.
The city's Aubrey Davis Park description identifies a regional park and recreation and transportation corridor of more than 90 acres. Built in 1992 to mitigate the impacts of I-90 highway work, it includes the Park on the Lid and the Mountains to Sound Greenway, also called the I-90 Trail. Listed amenities include restrooms, play areas, sport courts, public art, and open space.
For the wider picture, the city's March 2022 parks and open space plan records about 6.2 square miles of island land, 481 acres of parks and open space, and 28 miles of walking paths and trails. These are city-wide figures, rather than the length of a single route. Use the Mercer Island running routes guide to compare the park outing with other island route ideas.
The City of Bellevue describes the Mountains to Sound Greenway as a 100-mile corridor along I-90 from Seattle's waterfront to Ellensburg. Bellevue is building a 3.6-mile trail segment in phases to close a gap. Its first two phases completed 1.2 miles; the third phase began construction in June 2026 and is expected to finish by the end of 2027.
Bellevue's information lists an eastbound bike detour during October 2026-December 2027 and says funding for the final phases is not yet available. The corridor's overall length therefore should not be used as a ready-made running itinerary. Review pedestrian access separately from the bike detour and confirm the segment you intend to use before making an eastbound extension part of your plan.
The U.S. Department of Health and Human Services guidelines recommend 150-300 minutes of moderate aerobic activity weekly and muscle-strengthening activity on at least two days. They also remove the former requirement that activity occur in bouts of at least ten minutes.
Those are general activity recommendations, not a prescribed running distance for this trail. Plan the outing around the time, route access, and travel arrangements available to you. A shorter park visit and a longer trail run can be different choices for different days; neither needs an assumed mileage derived from the regional corridor's length.