Explain intersection based vs. loop based rail networks

[MeduSalem]

That would be my take on for the same:

8-direction rotary.JPG (198.9 KiB) Viewed 3289 times

Quite ridiculous in size of course, but a bit higher throughput. But I highly doubt that going from any direction to any direction is something that's really needed. I'd expect that most trains would never go in between 45° direction changes, therefore those direct links would never actually be required, resulting in almost the same size as a regular roundabout.

I mean really, the most common scenarios will be anything ranging from 90° to 270° in regular usage... the 45° and 315° entrances/exits would never be used, because of how you might want to use a shortcut somewhere further away of the intersection to spare the intersection the additional traffic.

PS. I forgot one chainsignal on the top entrance track and in the S/E-corner I used a normal rail signal instead of a chainsignal accidently. Damn it.

[Gus_Smedstad]

That would be my take on for the same:

My underlying assumption was that if you're going to make a huge rotary, you're doing it to avoid anything but the most basic rail switches, and hence you don't want the crossover points you've got in the center. Once you've got those it seems like you've got the drawbacks of an intersection, and possible deadlocks.

Not that we really need such monster intersections, of course. We're mostly talking about theoretical solutions to problems that don't really arise in normal rail nets.

[MeduSalem]

My underlying assumption was that if you're going to make a huge rotary, you're doing it to avoid anything but the most basic rail switches, and hence you don't want the crossover points you've got in the center. Once you've got those it seems like you've got the drawbacks of an intersection, and possible deadlocks.

Well yeah that's a different philosophy of course. I think since one needs chain signals anyways to avoid the deadlocks it doesn't really matter much anymore if the tracks intersect. It's not like 2 trains will be able to go into the same block even if they wouldn't intersect, which is also the case in your approach. It's a typical roundabout limitation that due to alternating entrances&exits somewhere a train has to wait due to the shared circle every train has to use.

Not that we really need such monster intersections, of course. We're mostly talking about theoretical solutions to problems that don't really arise in normal rail nets.

True. Nobody will ever need that. I mean maybe 4 to max 5 directions at different angles than standard 90° maybe in tight spots that don't allow one to break the intersection up in several simpler intersections, but probably never all 8 at the same time. xD


On a side note now I'm interested in if someone manages to actually do an 8-way intersection without a roundabout. Must be one spectacular mess. At least I know that 4-way intersections without roundabouts are do-able with the right spacing and use less space than roundabouts.

[Choumiko]

That's one interesting thread.

Can you show us a 4 lane and 8 lane loop then gus?
To increase throughput, some of us have started on 8 lane rail systems.

I think what he means with lanes is the number of tracks. So a roundabout with 4 entrances/exits, where every entrance/exit has 4 lanes (2per direction). Guess he wants to see a roundabout in a roundabout. I want to se e that too if it's as symmetric as medusalems

[MeduSalem]

Can you show us a 4 lane and 8 lane loop then gus?
To increase throughput, some of us have started on 8 lane rail systems.

I think what he means with lanes is the number of tracks. So a roundabout with 4 entrances/exits, where every entrance/exit has 4 lanes (2per direction). Guess he wants to see a roundabout in a roundabout. I want to se e that too if it's as symmetric as medusalems

Why not request a spiderweb? Because that's what it is going to look like. Railception incoming.

[OBAMA MCLAMA]

Can you show us a 4 lane and 8 lane loop then gus?
To increase throughput, some of us have started on 8 lane rail systems.

I think what he means with lanes is the number of tracks. So a roundabout with 4 entrances/exits, where every entrance/exit has 4 lanes (2per direction). Guess he wants to see a roundabout in a roundabout. I want to se e that too if it's as symmetric as medusalems

Why not request a spiderweb? Because that's what it is going to look like. Railception incoming.

exactly

as Choumiko said, i should have described it better because 8 lane loop does sound like it.. but in twitch world, 8 lanes means 4 lanes in both directions, making 8 in total.

So... for the 4 lane loop.. 2 in and 2 out for every entry. And 8 lane is 4 in/4out for every entry