Traffic signals for transit only

[cpzilliacus]

Saw them in Las Vegas (of all places) for a bus lane. Just LRT signals according to the latest MUTCD, no big deal...

Obviously they want to differentiate them from traffic signals so cars don't obey them and so buses/trams know to not obey the "normal" lights.

Obviously the white color make sense for that reason. 

Thanks for sharing your knowledge.  I have never seen anything close to the original signals above in the United States, and did not know they were in the MUTCD until your post.  See this for the details.

These would seem to make a lot of sense in intersections with heavy volumes of transit bus traffic, though  the MUTCD says the signals are for rail vehicles and makes no mention of buses in that description, though the text appears to allow them for queue jump applications.

In the cases of heavy rail systems, naturally, traditional signals are used. Red, yellow, and green mean pretty much exactly what you'd expect, though it gets more complicated when you have switches.

Though as discussed above, the Washington Metrorail system's trackside signals do not include green - only red and white (a "lunar" aspect) for "GO."

[on_wisconsin]

The Hiawatha LRT in the Twin Cities uses a modified version of the signals at the top of the page.

[Dr Frankenstein]

For the record, on heavy rail:
Double red: Stop.
Single Red (or double red, units not aligned): Stop and go, restricted speed (under 15 mph and watch for traffic; no clearance guarantee). Might mean Stop for some light rail systems.
Yellow or Yellow over Red: Proceed, next signal is red.
Green or Green over Red: Proceed at normal speed.

Position light signals: horizontal is red, diagonal is yellow, vertical is green. Amtrak uses coloured lenses on theirs but not everyone else does. And exceptions exist.

Like Duke87 mentioned, the presence of switches, interlockings and even grades and phase breaks make the whole thing get very complicated quickly, since the signals will give you instructions about the speed at which to get through and what to do afterwards. This is why some signals have two or three units, able to display combinations of colours called "aspects". And I won't even get started about dwarf signals, which are interpreted differently. To make things worse, many companies throw in extra custom signal aspects. BNSF is especially bad for this. In countries where signals aren't actually standardized, what I said above is subject to variation. Canada has a federal standard which must be complied to, I don't know about the U.S.

That said, I don't think it's wise to use colour signals on street runs, especially when those are frequent and/or traffic is dense. I'd rather see plain white lights with symbols (as seen at the beginning of this thread) or position lights (common on heavy rail in the U.S. from what I've heard).

[cpzilliacus]

For the record, on heavy rail:
Double red: Stop.
Single Red (or double red, units not aligned): Stop and go, restricted speed (under 15 mph and watch for traffic; no clearance guarantee). Might mean Stop for some light rail systems.
Yellow or Yellow over Red: Proceed, next signal is red.
Green or Green over Red: Proceed at normal speed.

Position light signals: horizontal is red, diagonal is yellow, vertical is green. Amtrak uses coloured lenses on theirs but not everyone else does. And exceptions exist.

Frank, this is correct.  And consider this - when the Øresund bridge-tunnel crossing between Denmark and Sweden, opened, in addition to the motorway crossing, this was the first time that the Danish and Swedish railroad networks had ever been linked (both networks are standard gauge, but prior to 2000, the only connection was by floating freight cars and passenger cars across on ferries).  The traction power voltages and the frequency of the power is different, and the signals (including ATC) are quite different.  And for more fun, Swedish railroads still run "on the left" on double-track segments.  All of this had to be dealt with when "through" train service across the bridge-tunnel started up in 2000.

Like Duke87 mentioned, the presence of switches, interlockings and even grades and phase breaks make the whole thing get very complicated quickly, since the signals will give you instructions about the speed at which to get through and what to do afterwards. This is why some signals have two or three units, able to display combinations of colours called "aspects". And I won't even get started about dwarf signals, which are interpreted differently. To make things worse, many companies throw in extra custom signal aspects. BNSF is especially bad for this. In countries where signals aren't actually standardized, what I said above is subject to variation. Canada has a federal standard which must be complied to, I don't know about the U.S.

I believe each of the U.S. railroads is to some extent free to set-up signal systems as it wishes to, though I suppose (in the United States) the Federal Railroad Administration could step in and order a railroad to make changes if it was deemed appropriate.

That said, I don't think it's wise to use colour signals on street runs, especially when those are frequent and/or traffic is dense. I'd rather see plain white lights with symbols (as seen at the beginning of this thread) or position lights (common on heavy rail in the U.S. from what I've heard).

Agreed. 

[deathtopumpkins]

US railroads use several distinct signal types that date to different historical differences between railroads - the different signal types do NOT line up with the modern Class I railroads, because, for example, the Chesapeake & Ohio used a different signal type than the Pennsylvania RR, and both of those ended up at least partially under the CSX umbrella today. Signals you see on the CSX mainline between Albany and Boston differ from the signals you see on the CSX mainline between Richmond and Newport News, VA, for example. Different signals are also used depending on the type of signalling setup, i.e. block signalling/PTC/etc.

My work involves interacting with the Massachusetts Bay Commuter Railroad (former Boston & Maine RR)'s tracks, and from this and talking with their flagmen I've learned that our signals, which are 3 round single-lens heads, mean as follows:

-Top lens: Green  - proceed
                Amber - proceed at reduced speed
                Red     - stop

-Middle lens: Always remains red except in the case of a special condition in the block AFTER next. i.e. a green on top and a yellow in the middle means proceed prepared to reduce speed at the next signal.

-Bottom lens: I don't recall exactly what this means, but I believe it regulates speed somehow, and was told it's almost never, ever, used.

In the several months I've worked here, I've never seen a signal display anything other than all red or green/red/red. It's very uncommon.

[cpzilliacus]

US railroads use several distinct signal types that date to different historical differences between railroads - the different signal types do NOT line up with the modern Class I railroads, because, for example, the Chesapeake & Ohio used a different signal type than the Pennsylvania RR, and both of those ended up at least partially under the CSX umbrella today. Signals you see on the CSX mainline between Albany and Boston differ from the signals you see on the CSX mainline between Richmond and Newport News, VA, for example. Different signals are also used depending on the type of signalling setup, i.e. block signalling/PTC/etc.

And we have CTC. 

I am not an expert on train signals, I only know about CTC because CSX uses it on at least some of its (former B&O) tracks in the Baltimore/Washington area.

[sp_redelectric]

Portland has similar signals for its MAX and Streetcar systems.  Not aware of too many bus-only signals other than queue-jumper lights (which look like regular traffic signals but are usually PV heads mounted with a "bus only" sign next to it).

Most MAX signals are two head with an amber left-right bar and a white up-down bar.  Amber means stop, white means go.  The amber signal will flash before it turns to white; the white signal will flash before it turns to amber.

Near switches there are additional signals. 

[national highway 1]

Here in Australia we do have special signals for buses and trams, as mentioned here:
Bus Signal - Red:
Red means any buses must stop. They must wait behind the stop line. Do not go through the intersection.

Bus Signal - Amber:
Amber means any buses must stop. They can enter the intersection if they are so close to the stop line that sudden braking might cause a crash.

Bus Signal - White:
White means any buses can proceed through the intersection carefully. This light usually comes on before the regular traffic signal turns green.


Tram Signal - Red:
Red means any trams must stop. They must wait behind at the signal. Do not proceed.

Tram Signal - Amber:
Amber means any trams must stop. They can continue if they are so close to the stopping point that sudden stopping might cause a crash or injury to passengers.

Tram Signal - White:
White means any trams can proceed carefully.


Along with the pedestrian signals as shown here,

I've noticed at a few newer intersections there have also had bicycle signals installed alongside them.
Bicycle Signal - Stop:
Signal especially for bicycle riders, using a red bicycle to indicate 'Stop'.

Bicycle Signal - Go:
Signal especially for bicycle riders, using a green bicycle to indicate 'Go'.

[mightyace]

US railroads use several distinct signal types that date to different historical differences between railroads - the different signal types do NOT line up with the modern Class I railroads, because, for example, the Chesapeake & Ohio used a different signal type than the Pennsylvania RR, and both of those ended up at least partially under the CSX umbrella today. Signals you see on the CSX mainline between Albany and Boston differ from the signals you see on the CSX mainline between Richmond and Newport News, VA, for example. Different signals are also used depending on the type of signalling setup, i.e. block signalling/PTC/etc.

Exactly.  Old Pennsylvania RR mainlines and Norfolk and Western mainlines used position light signals with white lights.  (For a long time, the N&W was controlled by the Pennsy.  Side note: Ironically, the N&W merged with the Southern RR to form the modern Norfolk Southern while Pennsy lines became part of the ill-fated Penn Central, then Conrail, then split between CSX and Norfolk Southern.)

The C&O and B&O implemented the similar COLOR position light system with uses positions like the old Pennsy/N&W but with color to clarify the meaning.  This included the Alton portion (Chicago-St. Louis) of what was once Gulf, Mobile and Ohio/Illinois Central Gulf.  That line is now Union Pacific!

Most other railroads used the traffic light style green-yellow-red or a single light with changeable lenses to change colors.

And, yes, with all the mergers and line sales over the years, all the large class I system have a hodgepodge of signal systems.  As time go on and signal lights are replaced, each railroad goes to a single standard.  So, the old color and monochrome position light signals in the northeast and midwest are rapidly disappearing.