What’s up with the trolley crash under City Hall?

SEPTA has spent years putting in place a collision-avoidance system in the trolley tunnel to keep vehicles from hitting each other.

So what happened yesterday, when a Route 10 trolley collided with a stationary Route 34 trolley in the Juniper Street station?

According to SEPTA, the safety system worked exactly the way it was supposed to.

SEPTA installed the nearly $25 million communications-based control system, or CBCT, in the 2.5 mile tunnel over the course of a decade. It took years to get the system fully up and running because of persistent glitches.

The system monitors the location of trolleys while they’re underground, sets speed limits and can engage trolleys’ brakes if they come too close to each other.

Similar collision-avoidance systems have also been installed on the Market-Frankford El and the Broad Street Line, and the federal government has mandated SEPTA install a collision-avoidance system on regional rail by 2015.

But what happened yesterday wasn’t a glitch. The collision-avoidance system isn’t active when trolleys are going under 8 miles per hour, said spokesman Andrew Busch. This allows trolleys at low speeds to follow each other into stations.

At Juniper, for instance, there are two trolley berths to allow multiple trolleys to take on riders at the same time.
When trolleys are going that slowly “it’s the responsibility of the operator to make sure that they’re basically operating in a safe manner,” Busch said.

“Yesterday wasn’t a speeding incident,” he added. The Route 10 trolley was going between 4 and 5 miles per hour at the time of the 11 a.m. collision ― meaning the system wasn’t operating.

(No one was seriously injured.)

Though there’s an “ongoing investigation,” Busch said “human error” caused the collision.

Contact the reporter at acampisi@planphilly.com