Dual tunnels
From OpenTTD
3-Way junctions
- Basic 3-Way
- Line Merge
- Half Cloverleaf
- Half Spaghetti
- Compact 3-Way
- Compact 3-Way B-M Junction
- Ultimate 3-way
- Half Transmogrified
- Braided Junction
4-Way junctions
- Basic 4-Way
- Roundabout
- Cloverleaf
- Spaghetti
- Star
- Complex Star
- Branch-Merge
- Over-Under
- Tetrathorp
- High Speed 4-Way Fly-over/under
- Pre-Signaled Roundabout
- Advanced Roundabout
- Right-of-way Roundabout
- 4-Way Triple Axial
- 4-Way Triple Axial 2
- Triple Via Mini
- Transmogrified
- Tightlong
- High Hill
Enormous junctions
Other junctions
Unuseful juctions
Sometimes you need to build long tunnels on your mainline. Tunnels do not have signals, so only one train can be inside at a time. This can cause traffic slowdown or jams on your main line.
Adding additional tunnels solves this problem. If one tunnel has a train in it when another train arrives, the 2nd train can continue through the 2nd tunnel instead of stopping.
Note the use of presignals to ensure that if both tunnels are in use, trains wait at the junction for the first available tunnel.
