Spiral Train station: benefits, problems, ideas

[mrvn]

I've been playing with train station in a setup with single directional tracks. For example I have a number of train stations in NS direction. On the west there is a track going south and on the east there is a track going north. Now in each station trains can enter from the west or the east and leave to the west or east. Trains never turn around or cross tracks while on the main tracks.

While building a station able to handle 2 or more trains, so basically adding a waiting bay, I noticed something, especially with empty stations. Trains coming from the north enter the station from the west. Then they drive half way around the station to where trains from the east enter. Then they drive through the waiting bay that goes half around the station as well and then they enter the station proper which ends near to where trains enter on the east. So trains from the north drive about 1.5 times around the whole station in kind of a spiral. And with an empty station and some break research they come in with quite some speed on them. Not sure when exactly they start breaking but they leave the NS track a lot faster than without that extra loop.

Similar a train exiting to the west going south has to drive around inside the station first. The station naturally exits to the east so it's a half turn around the station. When the train enters the NS track it already has some speed picked up. I'm considering making the way longer. Taker another loop before exiting even to the east to pick up speed.

Moving trains on the main track at greater speeds seem to be a benefit.

A problem though is that this only works if the way is clear. If there happens to be another train then a signal turns red, one of the trains breaks and you have a slow train on the main tracks again. Sounds like something chain signals or some wired signals should be able to optimize. E.g. only let the train leave the station when it can slot into the main traffic without stopping.

Another problem currently is that entering and leaving tracks inside my station cross. I simply didn't have enough space and even have them use the same tracks at times. Maybe this should be a double spiral that doesn't cross?

Has anyone else experimented with adding slowdown and speedup tracks to your stations to improve movement on the main tracks?

[Durentis]

A problem though is that this only works if the way is clear. If there happens to be another train then a signal turns red, one of the trains breaks and you have a slow train on the main tracks again. Sounds like something chain signals or some wired signals should be able to optimize. E.g. only let the train leave the station when it can slot into the main traffic without stopping.

Another problem currently is that entering and leaving tracks inside my station cross. I simply didn't have enough space and even have them use the same tracks at times. Maybe this should be a double spiral that doesn't cross?

I don't think you can avoid either of these problems completely in any reasonable way. The longer exit time might be beneficial despite the occasional collision, but I'm not sure it's worth the space and travel time.

Best I can think of at the moment is running a four lane track (two in each direction). Trains exit stations onto the closest lane and there must be a crossover from the closest lane to the inner lane just before the station exit. You need chain signals exiting the station and entering the crossover. This would keep approaching trains at speed as a train exits your station as long as the inner track is still free, which it should be. But it can still result in a stopped train once the train fully exits the station and allows an at-speed train to come up behind it. Similar idea for station entrances. Not sure there's room to really do it properly. Perhaps you can fiddle with the train's pathfinding by adding dummy train stops on the "slow lane" to keep trains preferring the fast lane (because they add to the path distance), but I still don't think you can guarantee full speed when they cross to the "fast lane" without long lengths between crossovers. Maybe, though.

Some fun stuff could happen if we had access to a train's current speed and location relative to upcoming signals and could activate/deactivate the signals as desired, but we don't.

I think it's more trouble than it's worth, regardless.

My preference would be to keep a high locomotive to wagon ratio to keep their acceleration high, use well-designed intersections, and avoid small loops in the main tracks whenever possible because these can eventually deadlock.

[mrvn]

My idea was to stop the train trying to leave if there isn't a large enough gap on the main track to slot in. That would guarantee at least the minimum speed the train gets before leaving a station for all trains. So turn the signal right after the train stop red if a signal somewhat before the junction to the main track is not green,

As for a trains speed and position. Position is easy to read from red signals. Speed you get from the number of yellow signals before the red one.

Someone also posted something recently to set the trains speed. Connect two signals, the first just reads and the second is set to close when yellow = 1. The distance between the signals then equals the breaking distance for the speed the train can have. Any faster and it will slow down because the second signal will be red.


All of this needs massive amounts of space. Like you have to check for a train on the main track going maybe 500m back from the junction to get reasonable speeds. Might be fun to build though.