Why, yes, the B Line is stuck this rush hour because the driver of a U-Haul van somehow managed to get it stuck on the tracks near the BU Bridge. Annie Whitehouse, who captured the moment for posterity, suggests:

U-Haul stuck on the tracks at the BU Bridge is the most Allston thing to ever happen.

At least since the last most Allston thing to ever happen, back in 2015.