A disabled trolley near Kenmore forced the MBTA to extend bus substitution on the D Line from Kenmore all the way to Fenway Sunday night — an unplanned disruption layered on top of the nine-day Green Line shutdown already upending service for Brookline riders.

Universal Hub reported the extra bus substitution kicked in at 8:53 p.m. Sunday, the second day of the planned shutdown. The MBTA hadn't confirmed the cause as of Monday. The practical effect: D Branch riders coming in from Brookline Hills, Brookline Village, Beaconsfield and Reservoir faced shuttle buses not just to Kenmore as planned, but potential further delays connecting through Fenway too — on top of the 25 extra minutes the MBTA already told riders to expect during the shutdown.

The planned shutdown runs Aug. 8 through Aug. 16 and affects all four Green Line branches. On the D Branch specifically, trains aren't running between North Station and Kenmore, with free shuttle buses covering Kenmore to Back Bay instead. It's part of a bigger signal-system overhaul replacing 90 track circuits, installing more than 72 miles of new signal cable, and upgrading 129 signal components — necessary work, since the MBTA says the current signal system is more than a century old.

Fares are waived at Kenmore, Riverside and all surface-level stops west of Kenmore, and the Worcester Commuter Rail is fare-free between South Station, Back Bay and Lansdowne for the duration. Every shuttle bus is wheelchair-accessible, with lift-equipped coaches on weekdays and ramp-equipped low-floor buses on weekends; accessible van service is also available between Kenmore and North Station through station staff or call boxes. Transit Ambassadors are posted at stops to help riders navigate the changes.

The moment this shutdown wraps Aug. 16, a new one begins the next day: from Aug. 17 through Oct. 4, westbound C Branch trains will skip Brandon Hall entirely for accessibility upgrades, with Fairbanks Street or Summit Avenue as the nearest alternatives, both just a short walk away.

Questions can go to the MBTA's general information line, 617-222-3200, weekdays 6:30 a.m. to 8 p.m.