signals on the B&A

when i was in Framingham and Ashland yesterday, the signals only came on when there was a train near by., but i only saw lights at the CP's and they came on when the CP's were beign used. How long has the B&A's signal system been like this and why is it like this? save power?

MBTA F40PH-2C 1050 wrote:How long has the B&A's signal system been like this and why is it like this? save power?

Since the late 1980s, I believe. The system is one of cab signals w/o wayside intermediate signals. This was an experimental Conrail project designed to eliminate the maintenance of the intermediate signals. It also adds to safety in that operators of trains have a continuous indication, displayed in the cab, of the condition of the track ahead.

The track between controlled points is divided up into segments. Cab signal indications change according to whether these segments in front of a train are clear of trains and other equipment that shunts track circuits. Open switches on the main track also affect the signals displayed in the cab -- as do broken rails or loose bond wires.

A train approaching a CP which has it's signal at "stop," (or an occupied segment of track) will first get an "approach" in the cab, and then a "restricting" as the train gets closer to the wayside CP signal (or occupied segment).

Thanks LCJ

Even before the the current installation on the B & A, the older installation of searchlight signals, probably from the early 1950s, were "approach lighted." Boston & Maine also used the same type of workings in its searchlight signal installations. New Haven's signals were always lit.

the New Haven signals are always lighted because of the amount of traffic, correct?

eddiebear
The B&A ABS searchlight signals in use before the changeover to TCS/261 in the mid to late 80's were continuously lit. They were of the typical NYC type with the small target surround, unlike the B&M and New Haven which used the large target.
"BandAfan"

I think the choice of approach lighted or continuosly lighted signals was made by a railroad's Chief Engineer. There were some areas on the New Haven that were not exactly overflowing with traffic in the 1950s and 1960s, such as Framingham-Framingham Ctr, P & W route, Norwood Central to Readville with continuosly lighted signals.

The B&A automatic semaphores in several locations, including Washington Hill, had an Approach Clearing feature. They would be normally in the Stop position until a train entered the block to the rear, and then they would move to the clear position (or whatever the system called for). It was somewhat the same circuitry as Approch Lighting, with the signal control circuit (instead of the lighting circuit) breaking over the back contacts of the track relays and repeaters in the block to the rear of the signal.

The purpose was to prevent a false clear indication if the signal was frozen or covered with ice.