One of the most frustrating “pain points” for any player—new or veteran—is the discovery of a gridlocked network. A single misplaced signal can halt an entire economic engine.
The Symptom
Trains are facing each other on a single track, or a junction is “frozen” with no trains able to enter or exit, even though there is empty track ahead.
The Fix: ‘The Spacing Rule’
The primary cause of deadlocks is often insufficient spacing between signals or junctions.
1. The Length Check
Ensure that the distance between two signals is at least as long as your longest train.
- The Problem: If a train stops at a signal and its “tail” is still blocking a junction behind it, a deadlock is inevitable.
- The Solution: Use the
Measurement Toolto verify tile counts.
2. Path Signal Logic
In modern OpenTTD, Path Signals are the gold standard.
- Replace standard block signals at junction entrances with Path Signals.
- These allow trains to reserve a “path” through the junction, only entering if they have a clear exit.
Technical Reference
If you are using specific NewGRFs that modify signal behavior, check your openttd.cfg for these entries to ensure pathfinder is optimized:
text
[pf]
pathfinder_for_trains = 2
wait_for_pbs_path = 30
reserve_paths_through_junctions = true
Curator’s Note
Use the High-Contrast Teal signal highlights to easily spot signal directions in Dark Mode. It saved me hours of frustration when debugging the mainlines on my last map.