difference

[zggz]

Can someone explain for me what is principal difference between two setups? Why everyone use 1-st?

[Koub]

Because viewtopic.php?f=194&t=46855 probably.

[BlakeMW]

Well the first obvious thing is the tracks are closer together with the left junction: that's the most commonly used spacing probably because it's the minimum spacing that allows a compact "crossover track". In addition the left junction is more efficient (has a higher throughput per minute), one reason is that it uses "split before merge", that is the tracks going in the 3 possible different directions all split off from each other, before crossing other tracks or merging, generally speaking split before merge junctions enjoy fewer "collisions" between trains (a good example of a junction which is "merge before split" is the common roundabout - trains merge onto a shared track before splitting off, resulting in contention for that shared track).

[zggz]

Well the first obvious thing is the tracks are closer together with the left junction: that's the most commonly used spacing probably because it's the minimum spacing that allows a compact "crossover track". In addition the left junction is more efficient (has a higher throughput per minute), one reason is that it uses "split before merge", that is the tracks going in the 3 possible different directions all split off from each other, before crossing other tracks or merging, generally speaking split before merge junctions enjoy fewer "collisions" between trains (a good example of a junction which is "merge before split" is the common roundabout - trains merge onto a shared track before splitting off, resulting in contention for that shared track).

Big thank you man!

[Lilly]

Consider what happens when two trains enter from opposing sides and both want to turn left:

junctions.png (527.85 KiB) Viewed 4451 times

[zggz]

Consider what happens when two trains enter from opposing sides and both want to turn left:

junctions.png

Thank you!

[Zanthra]

Well the first obvious thing is the tracks are closer together with the left junction: that's the most commonly used spacing probably because it's the minimum spacing that allows a compact "crossover track". In addition the left junction is more efficient (has a higher throughput per minute), one reason is that it uses "split before merge", that is the tracks going in the 3 possible different directions all split off from each other, before crossing other tracks or merging, generally speaking split before merge junctions enjoy fewer "collisions" between trains (a good example of a junction which is "merge before split" is the common roundabout - trains merge onto a shared track before splitting off, resulting in contention for that shared track).

Our of curiosity, is a crossover track one that lets a train onto the opposite direction track? If so when and where do people tend to use them? I have almost never seen them in Factorio train builds. If they don't, I think it might make a lot of sense to pack the rails closer together (1 track width empty between for drive on left, and 0 track between for drive on right) normally and use a longer runup to space them however nescessary for junctions.

[BlakeMW]

Well you can space tracks out in the runup before a junction, but what do you gain by doing that rather than always having them space 2 apart? And if you use a consistent spacing you can readily add junctions into existing track and will have room to place signals when tracks cross. Also if you use a spacing other than 2 all kinds of junctions will be larger (because no spacing expands to 3 for junctions, and 1 spacing expands to 4: a spacing of 2 remains at 2 for junctions, especially T junctions).

Anyway by crossover I mean mainly when a train needs to cross from one track to another. The tracks could be going in the same direction such as when splitting off to multiple stations. Personally in some cases I merge a two-way line down to a single line and players who use 4 (or more) lane trunkways presumably merge them down to smallers ones.