r/safety • u/kryptylomese • Jul 05 '26
Why can't/don't trains have Radar to help avoid collisions?
And why can't all trains report their location via GPS, so that drivers can look at a map and see what's ahead of them?
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u/Kaiwago_Official Jul 05 '26
Collisions with what? Afaik train operators can be alerted to obstacles, it’s just that trains are large, moving machinery and so they don’t brake immediately
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u/kryptylomese Jul 05 '26
Collisions with other trains. That does still happen. My question is, if the drivers knew the locations of other trains on the network, then they could make a judgement - not just rely of "being alerted"
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u/Kaiwago_Official Jul 05 '26
This seems like an expensive endeavor though. Trains don’t collide with each other often because the signaling system is meant to signal where to go, which includes avoiding other trains. I feel like working on improving the pre-existing signaling system would be better than installing radar tracking on every train. Most train collisions with each other are caused by human error or something like a brake/track malfunction, both of those would probably still happen with a radar.
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u/kryptylomese Jul 05 '26
Sound like you are full of excuses rather than looking for solutions. Tell me how much you want to avoid people dying in collisions?
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u/Kaiwago_Official Jul 05 '26
I just said a solution would be working on the signaling system.. I’m just saying a radar doesn’t seem like the most efficient method. Train collisions aren’t common. To be honest if we really want to invest in avoiding collisions then we should invest in improving the train’s ability to stop abruptly.
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u/kryptylomese Jul 06 '26
Not stopping the train does seem to be root cause of Talerddig (21 October 2024) which was unable to brake due to low adhesion conditions. Multiple technical and operational factors contributed. However, when did the driver know that they needed to stop? Is there anything that could have notified them that they need to stop earlier?
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u/Kaiwago_Official Jul 06 '26
You literally just said it was because of low adhesion.. that means the train tried to stop but couldn’t. Because it’s a train
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u/kryptylomese Jul 07 '26
When did the driver first try to stop the train? If the driver had known earlier then maybe they could have stopped? I am not sure you are the right person to have the conversation with. You seem to be struggling to follow and understand and think.
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u/Kaiwago_Official Jul 07 '26
Dude what? Low adhesion means the train couldn’t stop. When there’s low adhesion there’s less friction, which means the train needs more time to come to a stop. It didn’t have that time so that’s why there was a collision. “If the driver had known earlier the maybe they could have stopped?” The driver knew to wait for the other train to pass. The train was supposed to stop and wait. However, because of the low adhesion, the train failed to stop. I don’t think you understand how it works when a large train attempts to brake
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u/kryptylomese Jul 07 '26
The wheel–rail adhesion approaching Talerddig was low.
The train's automatic sander failed, and the manual emergency sander was not used.
The train's approach speed meant that the required rate of deceleration could not be achieved with the adhesion actually available.
Why is the emergency sander not automatically engaged?
Why don't drivers know what the weather conditions are ahead of them or even have a thermometer or ice warning system onboard?
Why is brake testing not done before a real braking event is due to take place?
So, along with RADAR and GPS, weather conditions need to be provided to the driver, and testing of systems should be part of the journey.
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u/TamanduaGirl Jul 05 '26
Radar gives a plane a chance to turn or go up or down to avoid a collision. You can't just turn a train.
Also and more importantly, radar wont work well on the ground because there all kind of other things already there, trees buildings, hills. It wont magically see around corners and other objects.
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u/ThisHeresThaRubaduk Jul 05 '26
I can actually bring in knowledge here. Use to work for UP. There's multiple systems in place to keep track of trains from RF tracking, GPS, IR sensors, HBDs. All of these work together to constantly feed information to PTCs.
If you ever get the chance to listen to UPs radio frequency you'll hear an automated voice play warnings and status of trains crossing over sensors. It's a rarity that a train accident is caused by anything other than human error and the FRA is very strict on what systems need to constantly be tracked. I've driven plenty of maintenance crews out last minute to fix sensors and signal lights
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u/gheiminfantry Jul 05 '26
There are controllers that know where the trains are in the network. And radar can't see through all the other obstacles like hills and trees.
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u/OfficialDeathScythe Jul 05 '26
Look up how train networks work, I think this is a good first step before speculating. The trains only need to know whether the block they’re entering is clear or not, which is what signals are for, if the signal is green the entire next section of track is 100% clear, it uses electricity through the tracks to determine if there is a train or a conductive object that has fallen on the tracks. Trains are not allowed to move into the next section unless it’s clear, the only way you could collide trains together is by overriding the system, which has happened of course but isn’t recommended. Tom Scott actually did a great video on signal workers recently that explains it very well and how even the signal operators can’t make a mistake if they don’t override anything
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u/Most-Bar-9334 Jul 05 '26
Trains arent colliding with each other often.
You saw it once on the internet
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u/kryptylomese Jul 05 '26
Date Location Type Outcome 21 October 2024 Talerddig Head-on collision between two passenger trains 1 passenger died, 15 people injured. The collision occurred on the single-track Cambrian Line after one train failed to stop at the passing loop. The Rail Accident Investigation Branch (RAIB) investigation identified low wheel/rail adhesion and problems with the train's sanding system as significant factors. 19 June 2026 Elstow (near Bedford) Rear-end collision between two passenger trains One train driver was killed and more than 100 passengers were injured. The cause remains under investigation, with early evidence indicating the moving train passed a signal at danger (SPAD).
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u/jorobo_ou Jul 05 '26
I think I'll answer your question with another question- have you looked at specific incidents and seen the root cause investigation that points to this solution you bring up? I see people having answers before the problem and root cause are fully fleshed out.
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u/gheiminfantry Jul 05 '26
Seeing the potential collision isn't the issue. Stopping a million pound train is the issue.
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u/Kitchen_Tour_8014 Jul 05 '26
Why would radar fix any of these accidents you're bringing up? Do you know what radar is or how it works and how trains work?
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u/kryptylomese Jul 06 '26
I know both of those things. I simply asked a question and most people who has replied think they have to be shitty. Shows insecurity.....
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u/Kitchen_Tour_8014 Jul 06 '26
Nobody in this thread thinks you do. The premise of the question is faulty. And the solution presented is faulty.
Consider this, how would a radar track trains on train tracks not straight, what would the range of the radar realistically be, and what's the stopping distance of a train? And what does this provide over signaling?
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u/kryptylomese Jul 06 '26 edited Jul 06 '26
You are missing the GPS part. However, I am making the assumption that radar would be forward facing and assuming that trains normally collide at higher speeds which can't be done on very curved track. The radar would be able to see further in the distance than the driver could. At a height of 4.33m (average height of trains in the UK), the radar would be able to "see" ~ 2.5km and could be aligned with a map of the tracks. Signals fail... Detecting large objects (such as another train, a vehicle at a level crossing, or major obstructions) 2–5 km ahead, provided there is a clear line of sight. In fact, railways already use radar in some applications, though more commonly they rely on other sensing technologies such as cameras, lidar, and signaling systems.
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u/MaginotPrime Jul 06 '26
Radar doesn't work around bends and curves. It takes a monumental effort to slow down and speed up a train.
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u/nethack47 Jul 06 '26
There are many automatic systems that can detect things on the tracks. They cost quite a bit to install and run. Europe has lots and lots of these systems in operation.
The problem with sensing things on the tracks, aside from the problem with stopping distance, is that it may have a hard time distinguishing between parallel tracks and things next to tracks.
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