PDA

View Full Version : How to Find where to Place ATLS Crossing Triggers



jordon412
May 1st, 2017, 09:44 AM
Anybody who has experience using ATLS to operate railroad crossings know that how far to place the triggers from the road to activate the crossings before the train passes thru them can be a bit difficult. However, I've found a way to place the triggers without the trial and error in finding where to place them. You will need the following:
A calculator
And a way to convert Miles per Hour to Feet per Second

First you will need to convert the speed limit where you want to place the ATLS crossing. We'll start with the default speed limit in Trainz: 40 Miles per Hour.

40 Miles per Hour x 5280 Feet (1 Mile = 5280 Feet) / (divided by) 60 (Minutes per Hour) / (divided by) 60 (Seconds per Hour) = 58.666666666 Feet per Second

Now we need to look at the crossing:
There are two settings you need:
The intervals for flashers in seconds
Gate delay

The intervals for flashers in seconds determines how fast the lights will flash. The default is .75 seconds per flash.
The Gate delay is how many times the lights will flash before the gates begin to lower. The default is the lights will flash 5 times before the lights begin to lower.
By multiplying the gate delay by the intervals you will get the seconds between the lights starting to flash and the gates start to lower.

5 (flashes before the gates begin to lower) x .75 seconds (how fast the lights will flash) = 3.75 seconds delay between the lights starting to flash and the gates starting to lower.

With the Feet per Seconds and the delay between the lights starting to flash and the gates starting to drop, you can now determine how far away the triggers have to be from the crossing so that the crossing lights are activated and the gates start to drop by the time the train passes thru the crossing:

58.6666666666 (feet per second) x 3.75 (seconds before the gates start to drop) = 220 feet the trigger has to be away from the crossing for the train to pass thru the crossing at the same time the gates begin to drop.

However, at least for me, I don't know how long it takes for the crossing to drop to where it blocks the road. Because of this, I double the distance between the gates starting to drop and the gates are down, blocking the road:

58.666666666 (feet per second) x 3.75 (seconds before the gates start to drop) x 2 (to make sure the gates are down) = 440 feet

Therefore, in order for the gates to be down before the train, traveling at 40 miles per hour, passes thru the crossing, the outermost trigger (which actives the crossing) should be 440 feet away from the crossing. However, I would place the trigger 660 feet, 1/8th of a mile away, to be 100% certain that the gates are down when the train goes thru the crossing.

Please note that depending on the speed, the distance that you have to place the outermost trigger will have to be closer or further away from the crossing so that the gates are down by the time the train passes thru the crossing.

This math applies also to any crossings without gates.

Hopefully anyone who read this is able to understand it.

JCitron
May 1st, 2017, 10:05 AM
Cool, but my maths skills are about just dead now and are the equivalent of dog doo. Reading this made my eyes glaze over.

If you could put this together in an Excel spreadsheet and share it, that would be awesome so that brainless people such as myself can plunk numbers into the columns and have the answer spit out in front of us.

stouthm
May 1st, 2017, 07:02 PM
Lets simplify this. I multiply by 3 the speed of the train. That gives the gates plenty of time to lower and makes the vehicles stop in plenty of time before the train reaches the crossing. Example: speed of train is 30 mph then the trigger is placed 900 feet from the crossing. Works well for me.

epa
May 1st, 2017, 07:07 PM
Lets simplify this. I multiply by 3 the speed of the train. ... Example: speed of train is 30 mph then the trigger is placed 900 feet from the crossing.

Wouldn't that only be 90? Unless you mean to multiply the speed by 30. 30x30=900

Matt

jordon412
May 1st, 2017, 09:09 PM
Cool, but my maths skills are about just dead now and are the equivalent of dog doo. Reading this made my eyes glaze over.

If you could put this together in an Excel spreadsheet and share it, that would be awesome so that brainless people such as myself can plunk numbers into the columns and have the answer spit out in front of us.

Well, my iPhone has a converter app on it that I used to circumnavigate all the miles per hour to feet per second math. I figured I'd show the math needed to do the conversions instead of just saying 'You'll need an app to convert miles per hour to feet per second'.

blueodessey
May 1st, 2017, 09:27 PM
Thank you Jordan412, I'm adding this to my One Notes App in Win10, I just put in Crossings Griswold by BNSF50, and I was wondering how to set these up for distance indicators.

Your explanation works good for me..............:Y:

:clap:You made my day!

corvanel
May 2nd, 2017, 03:51 AM
And all this voodoo with feet and inches would not be necessary if you would use TRC. And metric of course, the only logical system.

JCitron
May 2nd, 2017, 09:06 AM
Anyone can convert feet to inches, etc., or use meters, didots, picas and points, chains, and rods, mm, cm, or any measuring system if they want.

The problem is the overall formulae should be in an easily accessible format so that numbers can be easily manipulated. This is where Excel, Open Office, or Google's equivalent come in

As I said before it's the maths that screw with the brain.

stouthm
May 2nd, 2017, 06:53 PM
Matt, you got me. Yes, I meant multiply by 30 and not 3.

cyberdongreen
May 3rd, 2017, 06:50 AM
Some time ago, I made up a table for personal use with information that I got from somewhere that I cannot remember right now. The speeds and distances are mph and feet but I'm sure somebody cleverer than me could convert it to kph and metres if they wanted to.

https://c1.staticflickr.com/5/4179/34425688195_1a7a7c405d_b.jpg

If it helps anyone then feel free to use it as you will.

Cheers

Dave

brucem56
May 4th, 2017, 07:44 AM
Excellent chart Dave, thanks for sharing.

justinroth
May 4th, 2017, 09:50 AM
I use a modified version of the B&M horn sequencer. I worked out that generally the number of feet the sequencer needs to be placed from the xing is line speed X 20. I then place my triggers appropriately some distance before. Of course the a.i. aren't always doing line speed so it needs to be fine tuned to work out most of the time. Once you add the variables of the possibility that a train is coming off of a siding close to the trigger things get a little more difficult. ATLS is great but I wish we had a more advanced and realistic tool to deal with crossings.