4 ms·
I get that this is sarcasm, but one of my idle day dreams is a safe, simple, mostly analog system that does exactly this between a set of moving train cars and
by NoToP 4y ago
I get that this is sarcasm, but one of my idle day dreams is a safe, simple, mostly analog system that does exactly this between a set of moving train cars and the last car on the rear (as a transitional state, the rear car eventually catches up and mechanically couples). I call it the reverse slip carriage. If it can be done, it would keep all the advantages of trains while also totally revolutionising possible service patterns. You could (for example) have a train where every carriage slips-off to make its own subset of limited stops and then slip-joins the next train to pass by. Passengers pick where to wait on the platform based on their destination, and there's always an express carriage to where you want to go. Another neat service trick this system could do is to have an 8 car subway which runs every 5 min that splits itself into 4 different 2-car light rail services every 5 min (rather than 4 subway branches with an 8 car train every 20 min (looking at Rockaway beach A train)). The ability to split and rejoin trains on the fly without stopping or spending time on coupling procedures is simple yet it would be profoundly game changing.
My current vision for the system basically amounts to electrically coupling the motors of the carriages such that any attempt to accelerate / decelerate one carriage transfers energy via induced voltage which accelerates / decelerates the other carriages by exactly the right amount. It's like an electrical version of how all the cable cars are holding on to the same rope. No computer, no glitches, entirely dumb components.
- cyclingfarther 4y agoWhat about the train drivers? They seem to still be necessary.
- duskwuff 4y agoBarely. In principle, railways would not be difficult to automate. But it hasn't happened at scale yet because industry regulations require that trains be manned, and railroad unions would strenuously object to any suggestion that this be changed (since it would likely put a lot of conductors out of their jobs).
- Findecanor 4y agoSome public transport systems have omitted the driver, but they still need a human attendant for safety to make sure that no passenger is stuck in the doors before departure (and other exceptions to smooth operation). One that I've ridden is Docklands Light Railway (DLR) in London.
- NoToP 4y agoOthers have pointed out driverless metro is already a thing in some places (from memory Singapore MTR, Sydney Metro, Docklands light rail in London, airtrain at JFK airport (NYC), Vancouver SkyTrain). But let's say for regulatory reasons you need a driver. So the way this would work is the electric motors in both the driver operated train and the slip carriage are electrically coupled via the rails. Technically the one driver is operating two trains with a single controller, but the circuitry is set up in a way that the second the slip carriage is always responding to the controls identically to the main carriage +a few m/s until it gets close enough for mechanical coupling. So the driver has no mental overhead in managing the secondary train sets. From a transfer of momentum perspective, his train behaves as if the slip carriages are already mechanically part of his train. For the sake of example, I'll focus on my second use case. A mainline heavy rail that branches into multiple light rail at the same service frequency. In this case, the carriages split off from an 8 car set into two car sets and coast to a stop at designated branch station (like old fashion slip carriages from the late 1800s). At those stations new drivers board to take over light-rail style operation. When the drivers complete the route they step off the train at which point the automatic reverse slip carriage system rejoins them into an 8 car train (one driver stays on to become the lead carriage). The drivers that stepped off then cross the platform to take over control of the next train to split itself. A strange but doable logistic coreography that lets metro lines branch more without intolerable service frequency.