The MBTA is blaming a "power problem" at Park Street for delays on the Green Line. Shortly before 8 a.m., Jed reported:

Just hit a big bump then saw sparks on the Green Line C Train. Track 2 disabled train.

At 8:25, he shows us how passengers got from the trolley to the station: Read more.

The T, which plans to run shuttle buses between Kenmore and Cleveland Circle on the C Line and Kenmore and Fenway on the Riverside line for the rest of the night following this morning's derailment, says it plans to resume regular service on the two Green Line branches first thing Sunday morning.

Henry Wong shows us the SUV whose driver somehow managed to get the vehicle's wheels ensnared on the inbound tracks of the C Line near Englewood Avenue sometime after 6:30 p.m. The T reports it had to stop trains at Coolidge Corner and bring in some buses to get riders between there and Cleveland Circle.

The MBTA reports delays on the Green Line outbound along Beacon Street due to a trolley that gave up the ghost.

UPDATE, 3:30 p.m. The power problems persist and are now affecting the Riverside line, too.

The MBTA reports "minor" delays on the C Line due to yet another unspecified power problem. Robinec helps define "minor":

I've been on the C line for more than 30 minutes now and we’re still not even underground.

A deceased trolley at North Station is causing "minor" delays for the ride to Lechmere, the MBTA reports.

MassDOT announced today that it's installing specialized traffic signal systems along Beacon Street in Brookline, and Comm. Ave. and Huntington Ave. in Boston that will switch to green lights for approaching trolleys. Mass. Ave. in Cambridge will get similar treatment for buses. Read more.

NBC Boston reports a trolley derailed at the Cleveland Circle yard and Beacon Street around 7:20 a.m. No injuries, no effect on service.

The T says service was pretty durn good on the four subway lines thanks to all the investments in things like new third rails and plows and dispatch centers.

So far this morning, the T has reported Red Line problems that include dead trains at South Station and near Ashmont, signal and switch problems on the Braintree branch and at Park Street. Green Line trolleys ran even slower than usual on the C line.

But as of 9:50 a.m., the T says everything's back to normal.