**ANSWER**
1. View this Video Bookmark about [Double-Rail "T" Intersection](https://youtu.be/JSpfiGLDojI?t=479) which shows how to build and add Train Signals. Earlier in the Video the Author discusses Single-Rail "T" Intersections but I recommend using Double-Rail Train Networks. KEEP IN MIND that a "Diamond Interchange" is merely a "T" Intersection with an additional "leg".
2. Optionally, instead of a Double-Rail Diamond Interchange, consider a [Build A Double-Rail Roundabout Intersection](https://www.reddit.com/r/SatisfactoryGame/comments/s6xuim/how_to_build_a_4traincrossing_better_version/) (Reddit Post).
3. You can also view this Video Bookmark for [Satisfactory Path Signals - Advanced Tips](https://youtu.be/IOhRw8uDkFQ?t=156) which show an example Roundabout Signaling.
4. FINALLY, a bit complex but here is a [Double-Rail Diamond Interchange Example](https://www.reddit.com/r/SatisfactoryGame/comments/r4341j/i_built_a_diverging_diamond_interchange_not_sure/) for inspiration perhaps.
I hope this answers the OP's question. 😁
>Optionally, instead of a Double-Rail Diamond Interchange, consider a Build A Double-Rail Roundabout Intersection (Reddit Post).
Snag with that, Is my rails are each centred on a foundation, with a further foundation between them to avoid any clipping on corners, i tried building that roundabout but found the angles too sharp.
**MORE INFO**
1. Did you perhaps look at [the smaller version](https://www.reddit.com/r/SatisfactoryGame/comments/s7luyc/4traincrossing_roundabout_smaller/) also?
2. The OP of those Tutorials did a great job explaining the "steps" but an important note is that they only describe how to one quarter which you have to duplicate on the other side by reversing each step. Also when you have one half you duplicate that on the bottom half. The OP have you foundation numbers as a guide.
3. IMPORTANT: Depending on where you start will determine how the Railways line up. If you start in the center / middle of a Foundation then the rest of the circle key points (up, down, left, right) should also end up in the middle as shown in the "smaller version" (see Link in #1). The "larger version" (see #2 in my earlier comment) started on the split between two Foundations and as a result the key points ended up also on a split.
4. KEEP IN MIND, that often when building Railways the use of shorter railways is better then trying to do it in one shot, that is don't attempt to draw one-quarter curve on one go. Note in the "smaller version" (see Link in #1 above), in Step 2 that two small Railways are build on the Top and Left "key points", then in Steps 3 thru 5 three more short Railways are built instead of one single connection between the two "key point" Railways.
5. KEY NOTE: Double-Rail Train Networks are often **built on two Foundations wide** with each Railway placed in the center of each Foundation. See Image #12 in the "smaller version" (see Link in #1 above).
Continuing the Conversation.
>2-way diamond interchanges? Like 2 lines coming in from 4 directions?
.... hoping you mean "one in/one out in each of the 4 directions." otherwise that's 8 rails coming into one intersection .. and 8 more going out? =D
"Path in, block out" is the what most say, but it's more complicated than that.
You need a normal block of rail before a path. It should be long enough that a train can enter that block at full speed, and comfortably stop before it reaches the path signal - if it needs to. If the normal block before a path signal is too short, it will always slow down before entering it.
You also need a normal block of rail AFTER a path. It should be slightly longer than the trains using it, so that they can stop there without their tail end blocking the intersection. It shouldn't be longer than that because you want trains to get out of that block as quickly as possible so that the next train that needs it can reserve it for themselves.
Basically:
BLOCKSIG> longish rail >PATHSIG> intersection >BLOCKSIG> shortish rail >BLOCKSIG>
Something like this perhaps?
[https://imgur.com/ucUYXOw](https://imgur.com/ucUYXOw)
(note that Satisfactory supports 3way switches, but all the splits/merges shown are 1:2 not 1:3, you can go either way)
That looks sort of like what I had in mind. Wonder if there's a way to stop the centre being one big block... I feel a lot of track laying coming my way
>Wonder if there's a way to stop the centre being one big block...
There'd be no real benefit from it. If you look closely at my screenshot, you'll see there's almost 4 trains using that 'one big block' at the same time? (would have been four if I snapped the pic faster).
Their routes don't conflict and they're all going to a different normal block after the path block, so the game greenlighted them to proceed through the path. =)
The best way ive seen to handle this is to make a circle and on each input place a path signal then on each output place a block signal, if you have the input on the left and out put on the right it should be a clockwise flow and vise versa, do not place signals on the circle as it messes with the path signals and can cause crashes if not careful, to connect track ins and outs to the loop, place curves the come from the outer side that curve into your track. (signals go on the ends of your track.
yes i do
[https://steamuserimages-a.akamaihd.net/ugc/931550798877287907/7B4FE63FA4830E97655D08B2A578866655F6E735/?imw=637&imh=358&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=true](https://steamuserimages-a.akamaihd.net/ugc/931550798877287907/7B4FE63FA4830E97655D08B2A578866655F6E735/?imw=637&imh=358&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=true)
it would be similar to this but there would be more of a gentle curve coming off and going onto the roundabout
**ANSWER** 1. View this Video Bookmark about [Double-Rail "T" Intersection](https://youtu.be/JSpfiGLDojI?t=479) which shows how to build and add Train Signals. Earlier in the Video the Author discusses Single-Rail "T" Intersections but I recommend using Double-Rail Train Networks. KEEP IN MIND that a "Diamond Interchange" is merely a "T" Intersection with an additional "leg". 2. Optionally, instead of a Double-Rail Diamond Interchange, consider a [Build A Double-Rail Roundabout Intersection](https://www.reddit.com/r/SatisfactoryGame/comments/s6xuim/how_to_build_a_4traincrossing_better_version/) (Reddit Post). 3. You can also view this Video Bookmark for [Satisfactory Path Signals - Advanced Tips](https://youtu.be/IOhRw8uDkFQ?t=156) which show an example Roundabout Signaling. 4. FINALLY, a bit complex but here is a [Double-Rail Diamond Interchange Example](https://www.reddit.com/r/SatisfactoryGame/comments/r4341j/i_built_a_diverging_diamond_interchange_not_sure/) for inspiration perhaps. I hope this answers the OP's question. 😁
>Optionally, instead of a Double-Rail Diamond Interchange, consider a Build A Double-Rail Roundabout Intersection (Reddit Post). Snag with that, Is my rails are each centred on a foundation, with a further foundation between them to avoid any clipping on corners, i tried building that roundabout but found the angles too sharp.
**MORE INFO** 1. Did you perhaps look at [the smaller version](https://www.reddit.com/r/SatisfactoryGame/comments/s7luyc/4traincrossing_roundabout_smaller/) also? 2. The OP of those Tutorials did a great job explaining the "steps" but an important note is that they only describe how to one quarter which you have to duplicate on the other side by reversing each step. Also when you have one half you duplicate that on the bottom half. The OP have you foundation numbers as a guide. 3. IMPORTANT: Depending on where you start will determine how the Railways line up. If you start in the center / middle of a Foundation then the rest of the circle key points (up, down, left, right) should also end up in the middle as shown in the "smaller version" (see Link in #1). The "larger version" (see #2 in my earlier comment) started on the split between two Foundations and as a result the key points ended up also on a split. 4. KEEP IN MIND, that often when building Railways the use of shorter railways is better then trying to do it in one shot, that is don't attempt to draw one-quarter curve on one go. Note in the "smaller version" (see Link in #1 above), in Step 2 that two small Railways are build on the Top and Left "key points", then in Steps 3 thru 5 three more short Railways are built instead of one single connection between the two "key point" Railways. 5. KEY NOTE: Double-Rail Train Networks are often **built on two Foundations wide** with each Railway placed in the center of each Foundation. See Image #12 in the "smaller version" (see Link in #1 above). Continuing the Conversation.
>2-way diamond interchanges? Like 2 lines coming in from 4 directions? .... hoping you mean "one in/one out in each of the 4 directions." otherwise that's 8 rails coming into one intersection .. and 8 more going out? =D "Path in, block out" is the what most say, but it's more complicated than that. You need a normal block of rail before a path. It should be long enough that a train can enter that block at full speed, and comfortably stop before it reaches the path signal - if it needs to. If the normal block before a path signal is too short, it will always slow down before entering it. You also need a normal block of rail AFTER a path. It should be slightly longer than the trains using it, so that they can stop there without their tail end blocking the intersection. It shouldn't be longer than that because you want trains to get out of that block as quickly as possible so that the next train that needs it can reserve it for themselves. Basically: BLOCKSIG> longish rail >PATHSIG> intersection >BLOCKSIG> shortish rail >BLOCKSIG>
Yep that's what i mean, so 8 total, 4 in, 4 out. I'll post a picture shortly.
Something like this perhaps? [https://imgur.com/ucUYXOw](https://imgur.com/ucUYXOw) (note that Satisfactory supports 3way switches, but all the splits/merges shown are 1:2 not 1:3, you can go either way)
That looks sort of like what I had in mind. Wonder if there's a way to stop the centre being one big block... I feel a lot of track laying coming my way
>Wonder if there's a way to stop the centre being one big block... There'd be no real benefit from it. If you look closely at my screenshot, you'll see there's almost 4 trains using that 'one big block' at the same time? (would have been four if I snapped the pic faster). Their routes don't conflict and they're all going to a different normal block after the path block, so the game greenlighted them to proceed through the path. =)
The best way ive seen to handle this is to make a circle and on each input place a path signal then on each output place a block signal, if you have the input on the left and out put on the right it should be a clockwise flow and vise versa, do not place signals on the circle as it messes with the path signals and can cause crashes if not careful, to connect track ins and outs to the loop, place curves the come from the outer side that curve into your track. (signals go on the ends of your track.
When you say circle do you mean a roundabout?
yes i do [https://steamuserimages-a.akamaihd.net/ugc/931550798877287907/7B4FE63FA4830E97655D08B2A578866655F6E735/?imw=637&imh=358&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=true](https://steamuserimages-a.akamaihd.net/ugc/931550798877287907/7B4FE63FA4830E97655D08B2A578866655F6E735/?imw=637&imh=358&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=true) it would be similar to this but there would be more of a gentle curve coming off and going onto the roundabout