In the old days it was simply a matter of calling out to the caboose… i.e. “have we cleared Main Street?” How would they know now with no one back there?
It’s a combination of things - one, the known length of the train (at least in the ballpark).
Second, a counter, probably part of the event recorder (as it is on ours), that can be set to that length and started at any given point as the locomotive passes said point.
Less important than crossings is control points, especially in dark territory.
The conductor’s paperwork will show how long the train is supposed to be. As a check, a roll-by or defect detector report can give a general idea as to whether the paperwork is fairly close.
In the ‘old days’ you weren’t calling out to the caboose. There weren’t radios on most railroads.
On the equipment I was use to it was on the receiving unit in the cab for the Rear End Device that had the counter. The train length was entered at the start of the trip. Any time there was a place you wanted to know you were clear of, like entering a siding, a button was pushed and that started a counter. When the counter got to zero, the rear of the train had passed the location where the button was first pushed.
Thank you…
“Old days” I guess is a relative term…in this case back when I was a kid in the 70s. Cabeese and radios I think.
Before radios there were pole lines. Most were 40 poles per mile which is 132 feet between poles. Since cars averaged 40 feet long for decades, that converts to 3 cars per pole, based on 44 foot coupled length which was very typical. Engineers usually knew how many cars they had.
Mac
The “length of the train”… does that include slack totally run out, in, or some average? How much slack would typically exist in, say, a 100 car train?
I posted this because I got to thinking about an incident I experienced back in 1982. I was the “guest” on a CP Rail grain train (six SD40-2s, three on the point and three midtrain slaves) heading from Kamloops, BC west to the next division point, North Bend, BC. After arriving in North Bend the engineer, brakeman, and I walked over to the local restaurant beside the station and sat down to eat. We were interupted by someone who told the engineer that our train had not cleared the last crossing. The engineer good naturedly said “you could have told me that when I was still on the train or give me another hundred miles to run”. He went back out and moved the train ahead 100 feet or so to clear the crossing.
I’ve observed something similar on my daily ride home. Just south of Cermak Road, our train usually diverges from the NS (ex-PRR) to a running track on the former CWI. Just as the last bi-level clears the crossovers, the engineer will open the throttle to get to track speed. Of course, it probably helps that we have the same crew every day and that the train is always eight cars.
A slightly different question: How does the engineer know his train has cleared the trailing point crossover switches so he can back the train onto the wrong main? Fifty years ago, an IC engineer relied on seeing a lit fusee in the air that was tossed by the conductor or rear end brakeman, who unloaded to throw the switches. I observed this one night when a manifest freight had to get out of the way of the City of New Orleans. Of course, he knew when he was close, knowing the length of the train. By the time the caboose reached the crossover, both switches were lined for the movement.
If someone has to throw the switch, that means there’s someone on the ground to call the train clear. It might be the conductor (who dropped off at the switch) or some form of support crew (travelling brakeman, etc).
Larry, both the conductor and rear brakeman dropped off; one threw one switch and the other threw the other. As it was, neither one relined the switches to the normal position after the freight was back on the right main–they relied on me to take care of them, so the engineer did not have to stop the train for them to board.
I have never seen a distance counter that had anything to do with the EOT. The counter is on the engine and tied into the speedometer. Now, just because you enter the distance, that doesn’t mean you have actually cleared the point where you started the countdown.
The reason there is a discrepancy is that, as I said, the counter is tied into the speedometer. If the speedometer tests fast over the test mile, the indicated train length will need to show longer than the actual train length in order to clear. If the speedometer tests slow over the test mile, the indicated train length will need to show shorter than the actual train length in order to clear. All of this is in proportion to how much the speedometer is fast or slow.
I found that the train length given on the paper work to be very accurate (Slack out). That is, as long as the paperwork matches the actual train (Units & Cars). If there has been a mistake and cars are in the train not on the list or cars on the list are not on the paperwork, then the reported length will be wrong.
One way that I could tell the train had more cars or less cars than the paperwork reports is that I would start the counter at the end of a certain curve after passing a defect detector. I knew very close how much distance should be left on the counter when the detector ended its second transmission. If the detector sounded before my known footage, then the train was short some cars. If the detector sounded pa
Train documentation on my carrier specifies the number of axles that are supposed to be in the train. Defect Detectors in their ‘defect message’ announce the number of axles that were counted by the detector. More axles than the train docs, more cars; less axles, missing cars. Many detectors also specify train length in feet.
The railroad for whom I worked for the last 15 or so years of my career would overstate lengths by up to 11 inches per car. Its equipment characteristics pages (derived from UMLER information) would round up the length (over coupler pulling faces) to the next full foot. I think I’d rather have my length overstated than understated when attempting to fit into a siding. But if you knew this, you might be able to make it help. For example, your typical unit coal train hoppers have a coupled length of 53’1". They’ll show as 54 feet in the reports. That’s 11 inches of excess length per car, or 1430 inches (119 feet!) in a 130-car unit train.
Most of our detectors don’t announce (although they do measure the count) axle count. Newer ones are starting to be set up to transmit the count.
I don’t use the counters much. The older ones (the ones on the head end EOT box although like it’s been said work with the engine axles) are often wrong. Nothing like going a quarter mile and watching it count off 8000 feet.
The newer, computer screen integrated ones, are usually correct. The problem is often the screens are used for DP operation and you have to get out of one screen and go through the menu to get the counter screen. (Some also have a timer option to time mile posts and check the speedometer.)
I know from the paperwork what my footage is. I convert it to miles and tenths of a mile, using a chart I made for myself rounding up to the next highest tenth. If my footage is 7500 feet, I figure a mile and a half. (A mile and a half is actually 7920 ft.) Most mainlines have mile, quarter, half-mile and three-quarter posts. When i need to know of being clear of a specific point such as a crossing, detector or end of a restriction, etc., add or subtract my train’s mile/tenth length to the specific point. For example going west the Beaver IA HBD is MP 219.7. I know I’m clear of it and should be egetting an exit message when my 7500 ft train reaches MP 221.2. (Actually, I’d be watching for MP 221.25. The quarter post.)
O
Jeff, does what I said about individual car-lengths still hold?
Jeff,
How do you know this? None of the mainlines out of here have anything but whole mileposts.
You brought up something that I had forgotten about. Our detectors at one time did announce the axle count and more often than not it was wrong in that it gave an odd number of axle count. They eventually turned the axle count feature off. When we had trains running over CSX rails, the CSX detectors we passed over would annouce a speed and length of train, but, that was some time ago. Don’t know if they still do.
I’m surprised to hear this. With two different screens, one should be able to have the normal screen with gauges and such, including a distance counter, while, having any DPU info displayed on the other screen.
Jim, (and Jeff)
Union Pacific put stripes on pole line poles every qurter mile. One stripe for one quarter, two for half, and three for three quarters. To the best of my knowledge this practice was peculiar to UP.
I do not know if UP expanded it to the former CNW, not do I know what they are doing today if there is no pole line.
Mac McCulloch
Yeah, counting poles was a way to do it if you didn’t have a counter or the counter didn’t work…then they cut our poles down! If you had been out there long enough, you knew about when you were on the main or out of a curve. Landmarks got etched in the brain after so many years.