Remaining automatic signals on Eastern Route

Does anyone know why the pair of automatic signals in Chelsea, between Eastern Avenue and Wonderland Interlocking, and the pair of automatic signals in Everett, between Second Street and Everett Junction Interlocking, are still in service? Last year, all of the other automatic signals on the Eastern Route were removed due to the installation of PTC, so why were the aforementioned automatic signals kept?

PTC was fully implemented prior to the cab signal "upgrade." There are still no cab signals from Wonderland in. A planned service disruption was cancelled in the spring due to a conflict between the lay of the land and how the new system works, so they went back to the drawing board to solve the problem before it becomes one. I've heard they plan on doing the work in the fall, and expect they'll wait to take the line out of service AFTER October!

Thank you for your reply, but I am not sure as to what the “cab signal upgrade” was. It sounds to me as though PTC alone does not allow for the removal of automatic wayside signals, and that, in order to remove them, a “cab signal upgrade” has to take place.

Correct - PTC is an overlay technology that uses the existing signal system. It's not a signal system on its own. The T needs to install a cab signal system on that portion of the line (which they plan to do); once that's done, the remaining automatic signals will get retired.

Since you mentioned that PTC uses an existing signal system, this must mean that it is being used with the home signals, given that they all are still in service, correct? And since PTC and cab signaling has allowed for the elimination of automatic signals, why do there still have to be home signals?

railfan1988 wrote: And since PTC and cab signaling has allowed for the elimination of automatic signals, why do there still have to be home signals?

For failover, when the magic box craps out?

Sent from my SM-S911U using Tapatalk

railfan1988 wrote: ↑Sat Oct 14, 2023 4:25 pm Since you mentioned that PTC uses an existing signal system, this must mean that it is being used with the home signals, given that they all are still in service, correct? And since PTC and cab signaling has allowed for the elimination of automatic signals, why do there still have to be home signals?

You ALWAYS still retain interlocking signals after the installation of Cab Signals and removal of automatic, that's just how it is. Has to be a failsafe and a method of having block occupancy within interlocking limits for track cars, when CSS is busted, etc.