Track detection - snow, rain?

I'm not so sure that exposed fiber would be a good idea, as it is a hazardous material. Optical fiber is quite thin, so a broken piece can easily penetrate skin - and it it breaks off inside the body, it won't show up on X-rays. If it gets carried into a blood vessel, the piece could be carried anywhere in the body, poking holes in blood vessels as it goes from place to place. Fiber cables in outdoor use must be buried.

spRocket, Yes I know, I work with it quite often. But its like anything else....you follow its safe handling procedures.

I think the cost of bonding fiber to the rail would be prohibitive. The cost of splicing fiber is high. Considering the environment, with vibration and the expansion/contraction of the rail and the effects of various routine rail maintenance operations, it would not be likely to survive very long.

Since the track circuit provides the dual functions of train detection and some assurance of rail integrity, it would be difficult to justify use of fiber for this purpose to allow some other technology to be used for the train detection.

clearblock wrote:I think the cost of bonding fiber to the rail would be prohibitive. The cost of splicing fiber is high.

I disagree, both are fairly cheap these days......in fact for splicing fiber, I have spliced 12 strands in seconds, not 30 minutes as it used take.

clearblock wrote:Considering the environment, with vibration and the expansion/contraction of the rail and the effects of various routine rail maintenance operations, it would not be likely to survive very long.

This I cannot argue.

What about track that has no joins.....track that is all wielded into one long endless piece? How do they build their circuits for this stuff?

CROR410 wrote:What about track that has no joins.....track that is all wielded into one long endless piece? How do they build their circuits for this stuff?

Train detection on continuous welded track can be accomplished via audio frequency signals applied to/received back from the rails.

Then by using mysterious electronic techniques such as frequency shift overlay (or maybe phase shift overlay?) the presence of a train in the block can be detected.

This detection method can also determine a train's approximate speed of approach. This is how grade crossing predictor circuits operate. (Predictors are the circuits that activate lights/gates at varying distances from a crossing depending on the train’s speed of approach, and also clear the crossing signals should the train stop short before reaching the crossing) . ...FB

Did I get this wrong?:

A southbound local 5-car freight train approaches Littleton, Co depot. (1967ish)

He activates the crossing signals, but stops beforeaching the grade crossing and backs into a siding. (Maybe to leave a railcar or to get out
of the way of a southbound through-freightrain.)

Crossing signalstoperating.

As I recall, the RXR crossing signals did NOT activate until the 50 mph train goto the switch or forward point from which the local freight had progressed and backed away from.

The signals activated only a few seconds before the train arrived at the grade crossing!!!

Was this a possibility?

I would hope not, but I recall something like that happening.

Thank you,

Apparently, the crossing did not activate until the main line train was on the island circuit. This should not happen but it is possible due to either human error or equipment problems. I don't want to speculate without knowing the details of how this crossing equipment is configured.

There was a similar circumstance that caused a fatal crash at Fonda, NY on CSX where the conductor of the stopped train had manually "punched up" the gates and did it for both tracks so it cancelled the approach detection for the train passing on the other track.

http://www.railroad.net/forums/viewtopic.php?t=10973

Thank you, Clearblock.
Very kind of you and I appreciate it.

How horribly tragic.

Why didn't anyone from the crew flag the crossing and stop vehicles?

But maybe they expected the other track to activate the crossing signals.
I would have.
I'd expect each track to have it's own independent detection that would override another's "manual cancel".
I'd expect the cancell button to be only for my circuit and not the other track's circuit.

The guy is justrying to help with traffic and this happens. So sad.

In Littleton, no one touched any control box.
Just threw the switch straight for the main line.

I guess the through-freight had to reach the point
where the other train had been before the signals activated.

Buthat does not make sense.

The switch was within the crossing circuit, but not close to the island.

But maybe I am not remembering this correctly.

Ever since I was 4 years old, I called the crossing signals "mee-mool" lights.

I dont know about rain or snow, but high humidity seems to trip the crossing signals on the Pope's Creek sub.

This creates a nasty delimia. After the gates have been down for 5 minutes and no train or train horn, do I go ahead and run the crossing?

Fiber has been laid and is being used in Rainbow Canyon after the flood of 2004 between Farrier and Caliente, NV for signals and radio.

The causeway across the Great Salt Lake is still TWC from Promontory to Lakeside as the salt water and foam come up onto the track and can cause signal discrepancies. I've been told that the UP would like to make the causeway fiber based but the cost is just to high.

gprimr1 wrote:I dont know about rain or snow, but high humidity seems to trip the crossing signals on the Pope's Creek sub.

This creates a nasty delimia. After the gates have been down for 5 minutes and no train or train horn, do I go ahead and run the crossing?

Have you contacted the railroad, especially the signal maintainer?

I would go around if I could see far down all tracks in both directions.

The only problem is, others may follow and not carefully look.

In north Denver, a man waited for an eastbound train to pass.
Asoon as it did, he couldn't wait for the gates to go up, androve around his gate and was hit and killed by a westbound train.

Sad that he waso stupid to not even consider that possibility and simply look first before crossing. (The westbound could have been easily seen.)

I once hand-raised a down gate to allow traffic to pass.
I was very careful to constantly examine both directions for anything, including a runaway railcar.

Several years ago, a man was welding rail south of Denver.
That section of southbound main line was shut down and trains diverted to the northbound track.
He also had a lookout.

Further south, a southbound train set out a fully loaded scrap metal gondola car because of brake problems.
It got away from them and rolled down hill, north, for miles.

Despite doing EVERYTHING CORRECTLY, the welder was hit and killed instantly by the car, believed to be traveling 70 to 80 mph on the welded rail.
His "spotter" was apparently looking north for trains coming from the north.

Don't railroads use torpedoes anymore?

Why do trains need track detection anyway? Can't the engineer just look down and say "Yup, tracks are still there!"

/me ducks, weaves, bobs, and runs for cover.

Riding in the locomotive in deep snow was very interesting.
You could not see the track or any sign of where it was.

Some interesting drifting could be mistaken for the track veering left, which it wasn't!

No torpedoes any more. As far as signalling goes, I cant see down around that bend in the canyon.