For a long time, the few things that could easily move around heavy machinery was trains. So lets say that there’s a train on a track, and its broken down and it either needs repairs, extra parts, or a replacement engine. Right behind it are several other trains, because this is a busy line.
How does a train bringing repair or extra engines deal with this? Its not like they can go right up to the broken down train because there’s other trains in the way. How do they get rid of the broken engine and the other carriages, because they’re on top of the tracks, and there’s no other tracks for them to move onto.
In: Engineering
You could push it (or pull it) with another train until there’s a siding to take it off the main track.
They just take another train and tow it back to the repair yard.
They can’t repair it in-situ, since it would be blocking the way for other trains.
If the train cannot be fixed in place, a rescue train can come from the front, as you said behind the broken down train, other trains might be stuck, but the line is clear ahead and the train can either be put on a trailer with a crane, rerailed and pulled back to a depot otherwise
They wouldn’t let the other trains onto that section of track.
Tracks have points along the way that can be used to divert the other trains around the blockage and the they send a train up the line to collect the rolling stock and the another to move the engine back to depot.
It’s chaos, but it’s easily fixed.
In most cases the solution is to just put the locomotive in neutral and push or pull it with another locomotive. In fact with modern multi-unit trains that have several locomotives it is not that uncommon for a locomotive to break down while under way without the train stopping, the broken locomotive will just carry on to the destination where it can be put into a shop.
There are some types of breakdowns where you can not put them in neutral as a wheel locks up. But steel wheels on steel tracks offer very little friction, especially if you put down some grease on the tracks. So you can easily push a locomotive or car into a siding so other trains can pass. Later on they can show up with a crane or some jacks and swap out the truck. These are entire complete units that can easily be swapped out even on the side of the road. For locomotives they have idler trucks without motors that they use to transport these broken down locomotives. It is also possible to use a big crane to lift the locomotive onto a rail car so it can be transported to a shop.
I’m a train driver. In general, as long as the faulty train can still roll, you either get a locomotive or another train to tow it back to the depot for repair. If the faulty train can’t roll, rolling stock technicians will go out to the site with devices called “wheel skates” to place under the wheels of the faulty carriages. Then the train can be towed back to the depot for repair, but very slowly.
Also, bear in mind that most trains can move both forwards and backwards. So if you do have a busy line, the trains stuck behind the faulty train have the option of reversing back to the previous junction where they can then switch to an alternate route to their destination.
There will **always** be other tracks for trains to move onto, even if it’s a single line track in some backwater area, there will always be a point where that single line splits onto a double line or a siding, trains can then be diverted and the rescue train can move up to the failed train and tow or push it to a suitable location, depending on the specific issues, track geometries and line usage at that time.
Also, just about every single train built in the last half century can move forwards or backwards with no issues, so the affected trains can simply reverse onto another track if so required.
Trains have been a thing for more than 200 years, the folks working the railways have solved this problem a LONG time ago.
The Öresunds bridge between Denmark and Sweden has a 100 meter gap without electrical over head wires. This is because Denmark and Sweden uses very different voltages for powering trains. The locomotives has two sets of transformers with automatic selection, so the drivers doesnt have to do anything but coast the 100 meters powerless on the middle of the bridge.
Theoretically there could be a case where a train ends up standing still powerless in the gap. For this reason, copenhagen has kept an old diesel powerd railbound snowmover who is also strong enough to go out on the bridge and pull a train 100 meters till it gets power. Its never been tested though.
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