According to the Roosevelt Island Operating Corp (RIOC):

Due to a vehicle accident(no injuries) by the RI Tram, there will be a delay in red bus service. Red Buses are currently being re-routed towards the East Roadway. An additional advisory will be sent when normal service resumes.

Sincerely,

Roosevelt Island Operating Corp Advisories Group

UPDATE – At 8:05 PM RIOC reports:

Service has resumed with residual delays. All roadways are open.