Credit to Ronald Long for raising the alarm
Construction zones have closed the Mountains to Sound Trail in three places in the Bellevue-Sammamish I-90 corridor! Numerous permanent routes are affected. Too many routes are affected to revise them all. This post provides suggested detours which riders should switch to when riding.
Factoria
The longest-lasting closure, which also affects the largest number of routes, is for the third phase of the Mountains to Sound Trail along SE 36th in Factoria. This will extend the trail to the intersection with 150th Ave SE near Bellevue College. Unfortunately the work entails detouring until the end of 2027!

The detour situation is a bit complicated. Westbound traffic can travel through the construction zone without detouring. SE 36th is narrowed to a single lane in the yellow zone. Bicycles share the single lane with cars, and can access the bike trail at 136th Pl SE (marked “Start of eastbound bike detour”). Less bold cyclists might feel crowded by impatient drivers here and prefer following the eastbound detour in reverse.
All eastbound traffic must detour. The city of Bellevue’s recommendation is depicted above. Below is a hopefully clearer RwGPS route, which avoids Bellevue’s wasted climbing.

After crossing Factoria Blvd on the bike bridge leave the trail and follow the sidewalk under I-90, then turn right on SE Eastgate Way. At the intersection with 150th Ave SE turn left and go up the spiral ramp to the ped/bike flyover across I-90. Then turn left on the sidewalk along SE 36th St. The flyover and sidewalk are supposed to remain open during the project.
Sixteen routes are affected:
#00541 – Mercer Island-Maple Valley-Redmond
#00850 – UW-Granite Falls-Fall City
#01801 – Club Car
#02176 – Eastside Loops
#02525 – The Commons-Renton-Maple Valley
#03227 – Postdoc Peddler
#03515 – A Sandy Arboretum Run
#04283 – Seattle Lakes & Rivers Cruise
#04329 – Newport Hills Two Lakes
#04715 – Three Lake Loop
#04918 – Edgy Lakes
#05281 – Happy Trails 200k
#05300 – Issaquah – Lake Sammamish – Mercer Island – May Valley Loops
#05322 – New Two Lakes
#05325 – I-90 Two Lakes Loop
#05416 – Seattle Trolls
Bellevue
A sewer project has closed the I-90 trail from Enetai Beach to the Mercer Slough. Work is projected to finish in the second week of December. Here is the recommended detour mapped in RwGPS:

You leave the I-90 trail at the hairpin turn, work northeasterly through the neighborhood to the traffic light crossing of Bellevue Way, then follow the connector trail back to the I-90 trail.
Please ride cautiously. A cyclist was killed at the Bellevue Way-SE 30th intersection on October 15. Poor signage on the detour is possibly implicated.
Fifteen routes are affected:
#00541 – Mercer Island-Maple Valley-Redmond
#00672 – Lake Washington Cruise
#00848 – Mercer Island-Selleck
#00850 – UW-Granite Falls-Fall City
#01801 – Club Car
#02176 – Eastside Loops
#02214 – Mercer Island-Carbon River
#02597 – West Seattle Edgy
#02795 – Leschi-Hobart-Redmond Loop
#02879 – Mercer Island-Auburn
#03227 – Postdoc Peddler
#03515 – A Sandy Arboretum Run
#04669 – Pizza for Lunch
#05300 – Issaquah – Lake Sammamish – Mercer Island – May Valley Loops
#05325 – I-90 Two Lakes Loop
Sammamish
NW Sammammish Rd is closed until mid December for installation of a fish passage culvert. Sammamish’s excellent detour plan ignores cyclists. Note the routing onto I-90.

There are two practical options. The least unpleasant is probably crossing I-90 on the ped/bike flyover to Newport Way. The flyover is very steep. Then ride Newport Way to the bike trail alongside 17th Ave NW which connects back to Sammamish Rd.

Riding eastbound there are no landmarks for the flyover apart from the structure suddenly appearing above you. The entrance is obscured by a slight bend in the trail until you are very close. Riding westbound the flyover is marked by a small “I-90 Trail” sign at a crosswalk.
The less attractive option is to continue on the I-90 trail and turn right on Lakemont and left on Newport Way. This requires negotiating a freeway onramp and two traffic circles on Lakemont.
Seven routes are affected:
#03502 – 520 Two Lake Loop
#03515 – A Sandy Arboretum Run
#04329 – Newport Hills Two Lakes
#04653 – Lake Sammamish Loop from Bryant
#04715 – Three Lake Loop
#05249 – Volunteer Park to Lake Sammamish Loop
#05281 – Happy Trails 200k
































