Unknown Object On Top of RRD Car

Yesterday, while waiting for my train at ME, I saw something unusual on Car 266 (Silverliner II). It was centered on the roof, and appeared to be some kind of rectangular antenna. Is this something new, and what is its function?

Thanks in advance.

I wonder if they're doing GPS with trains now like the buses have? I would think that would be pointless though as I'm sure whatever system they have now tells Control where each train is. Just guessing....knowing SEPTA they found another gizmo to waste money on.

GPS would, however, be useful for an automated stop announcement system. Might be a test for something like that....

Silverliner II 266 was the catenary inspection car. What you saw is the remains of the camera mounts which were located above the front center cab door and the middle of the roof of the car. There is also a "black box" inside the car which contained the video equipment. Pictures of the car when the cameras were still in service can be found here: http://www.trainweb.org/phillynrhs/RPOTW030608.html

Thank you Mr. Glen K. for a very consice answer.