Getting rid of signal bridges

Why does the MBTA seem to be getting rid of signal bridges in favor of signal posts next to the tracks?

Probably to make things easier for engineers to see to the side for the signals, and to also discourage railfans from climbing them to take pictures from the signal bridge.

Most railroads nationwide (probably Canada too) are doing this, not just the T.

Ok, I see, so it's not just a Boston-area trend, but a nationwide trend. That's good then, since signal bridges are now becoming obsolete.

Robert Paniagua wrote:Ok, I see, so it's not just a Boston-area trend, but a nationwide trend. That's good then, since signal bridges are now becoming obsolete.

Well, unless you like B&O color position light signals, or PRR/N&W position light signals...

there are a lot of places where you can't get ride of signal bridges, like interlockings on the NEC where you have 3 tracks, the signal bridges will always stay there, but there is no need for signal bridges on a double track mainline, the wayside signals make more sense

Not really, dwarfs could be used in replace of signal bridges at interlockings like Holden, Thatcher, etc.

but dont' dwarfs have different meanings? because at the east end of Back Bay station, the dwarf signal board, yellow over red is a different meaning then if it was on a wayside signal, which would be approach, but on the dwarf, it is a slow approach

Actually the difference is also in the red. On a dwarf:

Red over Yellow: Restricting
Yellow over Yellow: Approach Slow
Yellow over steady Red: Slow Approach
Yellow of flashing Red: Medium Approach

If you look in the NORAC book you will see all the possible ways each signal can be displayed depending on where you are.

For example coming in on a Franklin train you may see a Sloq Approach three different ways:

Walpole West: Red over Red over Flashing Yellow

Cove (just east of Back Bay): Yellow over steady Red

Tower One: White domino signal: positoned with white on bottom left and white towards top right.

yea, at an interlocking, like thatcher, a clear dwarf signal would mean slow clear, 15 mph through interlocking, so NORAC would have to change the rules on the signals, unlike a wayside clear signal

wow do I ever regrest asking this question....

haha its ok to ask questions, its just that dwarfs have different meanings than signals on a bridge, or wayside, didn't you learn something from these answers?

Yeah I learned that I'll never understand what all the differnet lights mean. They should really come out with a simpler universal system. So yellow means the same thing everywhere etc. Like a blinking yellow on the street always means the same thing... although thats not technically true since they use yellow as a traffic signal and just as an 'alert' type signal. Anyway you get the idea. Not that it matters as I probably won't be driving any trains anytime soon, other than the ones that are made of plastic.
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l008com wrote:Yeah I learned that I'll never understand what all the differnet lights mean. They should really come out with a simpler universal system. So yellow means the same thing everywhere etc. Like a blinking yellow on the street always means the same thing... although thats not technically true since they use yellow as a traffic signal and just as an 'alert' type signal. Anyway you get the idea. Not that it matters as I probably won't be driving any trains anytime soon, other than the ones that are made of plastic.
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Well, auto signals need to be consistant, since anyone licensed can drive anywhere. Imagine if every state had its own traffic signals...mass confusion.

Railroads aren't the same environment. No train crew can operate on a line unless they are properly qualified on it, which includes knowing what all the signals mean.

Also, railroad signals convey so much more information than a traffic light. Last time I checked, a gree arrow on the street didn't mean "clear for left diverging route, limited speed through intersection, maximum authorized speed when clear of intersection," although maybe making drivers think that way would get them driving a little better.

MBTA F40PH-2C 1050 wrote:yea, at an interlocking, like thatcher, a clear dwarf signal would mean slow clear, 15 mph through interlocking, so NORAC would have to change the rules on the signals, unlike a wayside clear signal

The signal displayed for moves through the interlocking would also depend on the maximum authorized speed which the crossover is designed to handle. For example Thatcher would probably have a Limited Clear as long as the crossover was designed for 45mph for pax trains. There's anoth example of how the flashing changes the meaning of the signal, LOL.

Green over Green: Clear

Green over Red: Slow Clear

Green over flashing Red: Medium Clear

Flashing Green over steady Red: Limited Clear

l008com wrote:They should really come out with a simpler universal system.

These signals that we use in this area are NORAC Operating Rules signals, which are pretty simple compared to some other railroads' signal systems.