• How do the signals in Reading (MA) work?

  • Discussion relating to commuter rail, light rail, and subway operations of the MBTA.
Discussion relating to commuter rail, light rail, and subway operations of the MBTA.

Moderators: sery2831, CRail

  by l008com
Back before they removed the signals from the Lowell Line, the general way signals seemed to work was that if there was a train in the current block or nearby block, the signals would light up. Otherwise, they'd be dark. That still seems to be the way they work in most spots where there still are signals.

Aside: Although I notice that sometimes signals closer to the train will shut off before ones further away. Like the signals on either send of Anderson Station. If a train is leaving to the North for example, the signals North of the station will shut off before the signals at the South end. It's like there is a smaller block embedded in a larger block, rather than the blocks just being lined up in a row up the line.

But anyway that's not what this post is specifically about. Reading also has lots of signals around. Signals to the North of the station seem to always be dark, unless a train is coming. But the signals on the South end of the platform, and the signals less than a mile to the South of that (adjacent to Market Basket), always seem to be lit up, and red, 24 hours a day. Just to the south of those Market Basket signals, theres another small, single signal right at New Crossings Road that only lights up as a train is going by,

I'm confused by the logic of how all these signals work, and why they don't seem to be consistent!?
  by edbear
Signals that are dark until a train shows up have "approach lighting."
  by BostonUrbEx
There's no rhyme or reason as far as I can tell. Some interlocking signals are approach-lit, some aren't. Some automatic block signals are approach-lit, some aren't. But I will say that newer installations seem to be trending towards approach-lit.
  by Engineer Spike
I haven't ridden the T in a long time. I have noticed elsewhere, such as where I work that some absolute signals are approach lit, while others will stay lit even with no train in the block, as long as there is a route lined up through the plant.
  by JCitron
It depends upon the signaling system used. From what I remember from riding the Haverhill line, there's a change in the kind of signaling system. There's a sign that reads something like begin and end automatic block system. I can't remember which one faces which way and looking at Google Earth does nothing to help the cause!

I do remember a railroad guy telling me that the B&M used AB signals on the Haverhill line while we were train watching and eating ice cream at Rose Glen in Ballardvale, but other than that the details are vague.

I did notice on the Google Earth images that the signals have been replaced from the famous GRS searchlights to the new generic tricolor LEDs and unlike the Searchlights, the signals in the images were lit up regardless of whether a train is there or not. This is also the case for the new interlocking signals in Ballardvale that were just put in and also the signals located along the Merrimack between North Andover, near the old Western Electric, and Bradford. On some clear nights, these signals can be seen from I-495 across located the river.