NTSB: Cold meds at the root of SEPTA's 2017 trolley collision

A Southeastern Pennsylvania Transportation Authority (SEPTA) trolley operator's repeated use of antihistamine medications likely played a role in two trolleys colliding with each other in January 2017, according to the National Transportation Safety Board (NTSB).

On Jan. 4, 2017, a SEPTA trolley traveling on Route 10 struck a stopped trolley unloading passengers on the same line. The striking trolley was moving at about 10 mph, NTSB investigators wrote in an accident brief.

First responders then transported 40 passengers and both operators to local hospitals for treatment of minor injuries.

The day before the accident, the operator of the striking trolley reported feeling ill with cold symptoms and a persistent cough. As a result, he took a cough-and-cold medication containing the sedating antihistamine diphenhydramine before going to sleep.

He reported taking another dose of the same medication before reporting for duty the morning of the accident, NTSB officials said. The day of the accident was one of the operator's days off, but he volunteered to work for overtime pay.

The operator's impairment from fatigue and the sedating effects of the diphenhydramine likely led to his failure to slow and stop his trolley before striking the other vehicle, NTSB officials determined.

The operator's illness also "negatively affected his medical fitness for duty," they wrote in the brief.

NTSB investigators noted that the operator's post-accident breath testing and urine drug screening came up negative for alcohol and other substances. The Federal Transit Administration's post-accident urine toxicology protocol doesn't test for diphenhydramine, however.