How Long Does It Take To Stop?

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Western Railroad Discussion > how long does it take to stop? Date: 12/07/01 10:08 how long does it take to stop? Author: santafedan I saw the thread below about the woman and the train that did not stop for her. Our model railroad club has an HO layout on display in a mbank lobby for the holliday season. It is 20 x 10 and is about 1 scale mile around. I time the speed of the train to 60 seconds per lap. When I am talking to someone about railroad crossing collisions I have a demonstration for them. With the momentum on, and going a scale 60 mph I give them the throttle, after a few instructions on how it works, and tell them to stop the train before it hits an imaginary car at the crossing. There are three crossings on the layout. They are amazed thet the train will go almost completely around the layout before stopping. Thus crossing all three highway crossings before stopping. This is very instructive believe me. It creates a good understanding on how long it takes to stop a train. This works with a freight of about 15 to 20 cars long and the passenger train with about 8 cars. It is fun to watch their faces when the tran will not stop. I have sometims put a soft foam auto on the crossing. [ Reply To This Message ] [ Quote ] Date: 12/07/01 10:43 RE: how long does it take to stop? Author: surflinerhogger Well, I can't speak to the freight trains today, but I can tell you that if I plug a little four car commuter train at 79, It takes a little more than 1/2 mile or better to come to a complete stop. But, remember we have more brakes per wheel than one. Add to that the disc brakes and it dies pretty fast. On the Superliner and Amfleet stuff, there are 16 brakes per car. Multiply that by the number of cars you've got and it comes out to a fairly good amount of braking power. I do know one thing, the braking power of any freight train is subject to a lot of variables. Outside of unit trains, each car weighs in different, has various brake riggings, different aged valves, loads, and a lot of other differentials that play into it. Many times, a crew will pick up cars that have been spotted in some places for weeks at a time, and while they may pass the air tests, the crew has no way of knowing how they'll brake until they need that first big gob of air. You can formulate tonnage, speed, number of operative brakes per ton and feet traveled and it'll come out looking pretty solid on paper, but in the real world, you never know until you have to dump it. [ Reply To This Message ] [ Quote ] Date: 12/07/01 11:33 Rule of thumb Author: powerbraker1 A good rule of thumb is to take the speed, square it, and that is a fair estimate of the distance required to stop in an emergency application of the brakes. This works fairly well for speeds from 5 mph to 60 mph, and I have had many occasions to test the theory with many different types of freight trains. So, 5 mph = 25 feet 10 mph = 100 ft 20 mph = 400 ft 30 mph = 900 ft 40 mph = 1600 ft 50 mph = 2500 ft 60 mph = 3600 ft I can't speak for speeds over 60 mph, because our maximum speed was 60 mph and I never exceeded the maximum speed (heh heh). Now, these are distances traveled in EMERGENCY, not when using a service application of the brakes. Bob Currie [ Reply To This Message ] [ Quote ] Date: 12/07/01 19:00 RE: Rule of thumb Author: DDG I think the biggest single factor in stopping sistance is T.O.B. That being tons per operative brake. A 30 ton empty car is set up to not quite slide the wheels in full emergency. Fill it with 110 tons of grain, and it still has the same brakes it did when empty. Throw in decending grade, speed, rain, ice, train length, etc, and no two trains behave the same way. Take the total tonnage for the train, and devide it by the number of cars, and you get a pretty good T.O.B. figure. The higher it is, the longer the stop takes, service, or emergency. [ Reply To This Message ] [ Quote ] Date: 12/08/01 16:16 RE: Rule of thumb Author: AAK Your figure for 60 mph is pretty close for a light train. I had an intermodal consisting of mostly empty or lightly loaded trailers. I hit a pickup truck and went to emergency the instant of impact. I wasn't sure he wouldn't stop clear of the crossing before that. I was traveling 58mph at the time. The train was 3300 ft long. It was dry and warm. The track was approximately level. The brake system was fully charged as I had not used air brakes for 30 minutes. We stopped with the last car about 3 or 4 carlengths past the crossing, about 3500 ft. That train was about 60 TPOB. However that is not going to work for a heavy freight of 90, 100, 140 TPOB. And I have had coal and grain trains go well over 2 miles from 50 mph on a 1% downgrade. One took three miles. I had just released a 12 psi set I had set account of a signal change. Within 60 seconds of that release we went into emergency because of and airhose bursting. It was rainig so the wheels were wet. So take your pick. 3500 ft or 3 miles. It depends. Also no coal/grain train going even 5 mph is going to stop in 25 ft. I'd say about 2-3 carlengths (100-150ft) if you are not on a down grade. [ Reply To This Message ] [ Quote ] Date: 12/08/01 17:15 RE: Rule of thumb Author: powerbraker1 Al, being a flat track boy I can't speak much for the long grades. I didn't create that rule of thumb. It is something we got from statistical analysis by the MOP. I never would have thought it was a good figure for 5 or 10 mph, but if you are running a true 5, not with the needle bouncing up to 6 or 7, then, unless you are running a grain train or a similar loaded unit train, you can stop pretty darn quick in emergency. I tried a few times, and it was close to 25 feet with a mixed cut fully charged. Same thing for 10 mph- I went an engine and a half with 50 cars. I have had a dynamiter on a grain train running 40, and we went almost a mile before stopping, and it was down a 1% grade. So, like any rule of thumb, it is just a starting point. It has stood up in many a law suit though- my dad used it all the time to defend the ATSF in crossing accident cases. I took my first rules class and rules test today in 12 years. Our road foreman of engines and rules instructor is a UP chief dispatcher. A pretty good class as rules classes go. I made a 97- not bad for not looking at a rule book for 12 years! Bob Currie [ Reply To This Message ] [ Quote ] [ Share Thread on Facebook ] [ Search ] [ Start a New Thread ] [ Back to Thread List ] [ <Newer ] [ Older> ]
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