THE SHORT ANSWER
Caltrans is scheduled to fully close State Route 84 (Niles Canyon Road) at the Arroyo de la Laguna Bridge in Sunol from 6 p.m. Saturday, September 26 through 8 a.m. Sunday, September 27, 2026, while crews install six precast concrete bridge girders.
This is a localized overnight SR-84 closure, not a closure of every road between Fremont, Sunol, Pleasanton and Livermore. Caltrans says the work is weather and schedule dependent, so travelers should recheck current conditions before departure.
WHERE THE FULL CLOSURE IS
The closure is at the Arroyo de la Laguna Bridge in Sunol on SR-84. Caltrans says the bridge replacement project began in May 2026 and this overnight operation is needed to give the crane crew a safe work area for girder installation.
Do not translate this work into a claim that all of Niles Canyon, I-680, Fremont, Pleasanton, Livermore or nearby attractions are closed. Check the exact route involved.
OFFICIAL EASTBOUND DETOUR
Caltrans says eastbound SR-84 traffic from Fremont will be directed onto Main Street, then north on Kilkare Road and Foothill Road, continue north on Castlewood Drive, east on Pleasanton-Sunol Road, and use the I-680 on-ramp.
OFFICIAL WESTBOUND DETOUR
Caltrans says westbound SR-84 traffic from Livermore will be directed to northbound I-680, take the Exit 25 Sunol Boulevard off-ramp, then travel west on Sunol Boulevard and Castlewood Drive before continuing south on Foothill Road toward SR-84.
HOW TO PLAN AROUND THE CLOSURE
If an itinerary depends on SR-84 through Sunol during the published closure window, build in extra time and use the posted Caltrans detour rather than relying only on a saved route. Caltrans says motorists should expect delays but does not publish a universal delay time, so Bon Voyage Compass will not invent one.
For a timed tour, airport trip, hotel check-in, event or reservation, verify the route shortly before departure. Conditions can change because the work is weather and schedule dependent.
AFTER 8 A.M. SUNDAY
Caltrans says all closures are scheduled to be removed by 8 a.m. Sunday, September 27. That is a scheduled reopening target, not a guarantee that conditions cannot change. This guide should stop presenting the closure as active after the window unless Caltrans publishes an extension or another current restriction.
WHAT BON VOYAGE COMPASS WILL AND WILL NOT CLAIM
Bon Voyage Compass can organize the official closure window and Caltrans detours into a route-planning checklist. It will not claim a particular business, attraction, hotel, rail service or unrelated roadway is closed without current evidence from the responsible source.
This guide was source-checked September 26, 2026 against Caltrans. Recheck Caltrans QuickMap and posted roadway information before travel because the operation is short-lived and schedule dependent.