When lineside signals were placed, how much consideration was given to the ability of the crew to view them from a distance? The two lines closest to me are the UP Milwaukee sub and the CP Watertown sub. In both cases, the lineside signals I most frequently check are positioned such that a visual observation from the cab would be difficult until after it's too late to stop.
In the case of the UP, the signal is placed just beyond a curve, meaning an EB/SB can't see it until it's within 200 yards or so. Had this been placed just before the curve, it would have been visible for several miles. The adjacent WB/NB signal is visible from a long straight stretch.
On CP, there is an EB signal which is immediately adjacent to traffic lights on both sides. This is a case where a main road parallels the tracks to the left and a long skinny parking lot parallels them to the right. A multidirectional set of traffic lights controls the whole thing. Looking from a vantage point a few hundred yards west, it seems it would be difficult to pick out which lights are which.
I'm interested in hearing how these examples would have affected safe operation back when these lines were initially constructed versus after CTC was implemented versus after PTC was implemented. I suspect that in the latter two cases, the signal aspect is known to the crew well before it ever comes into view.
Generally speaking, a train would never be faced with a red/stop without first seeing an amber at the previous signal.
Depending on the overall schema, a train might have several blocks worth of warning that they'd be facing a less-than-clear indication.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
AjsikWhen lineside signals were placed, how much consideration was given to the ability of the crew to view them from a distance? The two lines closest to me are the UP Milwaukee sub and the CP Watertown sub. In both cases, the lineside signals I most frequently check are positioned such that a visual observation from the cab would be difficult until after it's too late to stop. In the case of the UP, the signal is placed just beyond a curve, meaning an EB/SB can't see it until it's within 200 yards or so. Had this been placed just before the curve, it would have been visible for several miles. The adjacent WB/NB signal is visible from a long straight stretch. On CP, there is an EB signal which is immediately adjacent to traffic lights on both sides. This is a case where a main road parallels the tracks to the left and a long skinny parking lot parallels them to the right. A multidirectional set of traffic lights controls the whole thing. Looking from a vantage point a few hundred yards west, it seems it would be difficult to pick out which lights are which. I'm interested in hearing how these examples would have affected safe operation back when these lines were initially constructed versus after CTC was implemented versus after PTC was implemented. I suspect that in the latter two cases, the signal aspect is known to the crew well before it ever comes into view.
Signal systems are not designed for trains operating on a CLEAR signal to find a Red STOP signal as their next signal with any expectation of stopping the train.
Signal indications create a interlocking set of speed controls with each signal indication. The basic signals are CLEAR - proceed at maximum authorized speed. APPROACH - Upon sighting the signal, take action to reduce train speed to Medium Speed (which can be specified OR 1/2 the maximum authorized speed) AND approach the next signal PREPARED TO STOP. That next signal CAN be CLEAR, APPROACH or RESTRICTED PROCEED/STOP. Restricted Speed is a speed that will permit STOPPING your train within 1/2 the range of vision, not to exceed 15 MPH (some carriers make it 20 MPH). STOP is displayed on a signal that does not have a Number Plate - an Absolute Signal. Restricted Proceed is the STOP indication displayed on a signal WITH a Number Plate.
There are myriad of other indications in each carriers Signal Rule each to cover additional situations.
The carriers have changed signal locations over the years to fall in line with the kinds of trains they are currently operating and the normal stopping distances of those trains. Back in the WW II and earlier eras, signals were nominally spaced 1 mile apart, as most trains were in the 2500-4000 foot range. After WW II the carriers began spacing their signals nominally 2 miles apart as train sizes of 6500-9000 feet were the norm. These days signal spacing is nominally 3 miles as the normal train size is ranging between 10000 and 15000 feet in length.
Never too old to have a happy childhood!
Some signals seem like they were placed on purpose to be hard to see. We had one on a down grade, on a curve that most of the year was hard to see until you were within about a 1/4 mile. It was worse during late summer/early fall before harvest. If the farmer planted corn that year, you couldn't see it until you were on top of it. Soy beans, you could still see it for that 1/4 or so mile.
They have since moved that signal a few years ago with an upgrade of the signal system in that area. It was moved about a 1/4 mile back away from the curve.
Still, if you a familiar, that is qualified to operate, with a track segment, you should have a good idea of where each wayside signal is. As others have pointed out, a red signal shouldn't just pop out of thin air. You should have notice from previous signals that a signal could be red. If a signal should happen to be red and the last signal didn't require being prepared to stop at it, if you can't stop before passing it you won't be held responsible for passing it. (Note. What I'm trying to say is you still stop, you just don't have to throw it into emergency to stop at all costs before passing it.)
The only exception is if you're delayed in the block. If you pass a green signal and stop, or speed drops under 10 mph, you approach the next signal prepared to stop until you can see it, and the track up to the signal. Speed approaching the signal after the stop or slow down varies. Our rules for a freight train is in ABS, proceed at restricted speed. CTC proceed prepared to stop at the next signal.
Jeff
The BNSF signal department has a standard for minimum signal "preview" distance for new construction. I don't recall offhand what it is. Generally if they're gonna have trouble meeting the standard, they'll use a cantilever to improve preview rather than moving the signal location.
I worked on reconfiguring one urban junction that formerly had two control points within a thousand feet of each other. Both were both getting longer with the project, but for various reasons we would have preferred to keep the two separate. Unfortunately, there was nowhere to put absolute signals in between the two where they would be visible. They had to be up on cantilevers (because there were more than two adjacent tracks with no room for ground signals in between), but there are three overhead roadway bridges in the area that would block anything on a cant. So in the end we made it into one really long control point.
That's the only time I've ever seen an absolute signal location altered based on preview distances. It may happen more with intermediate block signals, which are more flexible and are often placed in part based on easy road access.
One other thought about visibility: in steam engine days, it was important for signals to be visible from the right-hand side of the cab. Left-hand signals were avoided, sometimes at great effort. These days LH signals are not a problem in most cases, but until those old signals were removed (e.g. as part of PTC implementation), you could see things like:
- Every block signal up on a cantilever (on parts of the Santa Fe that used left-hand-running double track)
- Eastbound and westbound signals on opposite sides of the track from each other on single track
- Sidings where the siding track swerved out away from the mainline at the ends, to allow room for a signal mast in between the two tracks. (In many cases the track alignment is still funky even though the signals have been moved.)
Dan
CSX placed a number of signals in locations that made them hard to see from a distance. While it's true that you should not come up on an indication requiring a stop without advance warning, it would make for smoother and more efficient operation if the signals were visible from as great a distance as possible. If you get an approach signal and the next signal is not visible until you are very close to it you must slow down enough that you are able to stop at the signal. If it were visible from a greater distance and seen to allow you to proceed, continuing to move at a higher speed would save fuel and reduce wear on the equipment.
Signals at crew change points should be placed at the locations where the change is made so you don't have to move at restricted speed to the next signal. CSX did this when they rebuilt Willard yard for the Conrail split.
I once asked a signal supervisor why so many signals are placed with poor sight lines. He said that their track maps show only straight lines.
mvlandsw CSX placed a number of signals in locations that made them hard to see from a distance. While it's true that you should not come up on an indication requiring a stop without advance warning, it would make for smoother and more efficient operation if the signals were visible from as great a distance as possible. If you get an approach signal and the next signal is not visible until you are very close to it you must slow down enough that you are able to stop at the signal. If it were visible from a greater distance and seen to allow you to proceed, continuing to move at a higher speed would save fuel and reduce wear on the equipment. Signals at crew change points should be placed at the locations where the change is made so you don't have to move at restricted speed to the next signal. CSX did this when they rebuilt Willard yard for the Conrail split. I once asked a signal supervisor why so many signals are placed with poor sight lines. He said that their track maps show only straight lines.
Just like the dispatcher's CAD screens.
"maps show straight lines"
Signal Supervisor, you are standing at the location and you can see whether or not it is straight.
Those doglegs around signals near the turnouts on a siding are there for clearance purposes. This former field engineer and roadmaster had several go rounds with operating trainmasters and superintendents that consistently wanted to raise siding and diverging route speeds when they found out what some turnouts were actually rated for. They did not want to hear that the curves in the doglegs could not handle those speeds and lay flat or the room to have spirals created.
Many of those pre-1950's doglegs around signals don't have the clearance to even be built in today's world. (but then again track centers for new siding construction have almost doubled in the last 50 years)
And then you have people that still think that to raise the speed of a switch only requires changing the frog out to a larger number frog without also changing the rest of the turnout. (and don't get the smirks and guffaws when they push the point and make an issue of it)
Love it when the signal guys and operating bubbas demand a sight obstruction be removed only to discover the offending obstruction is off the property.
Our community is FREE to join. To participate you must either login or register for an account.