What a signal should accomplish
A signal divides track into controlled sections. Its useful job is to decide where a train may wait without blocking something more important. Signal placement is therefore a space-planning problem, not a decoration problem.
Before adding signals, run one train over the route. This proves that track, terminals and vehicle compatibility are correct. Add a second train only after deciding where the two trains can safely wait or pass.
Create useful sections
The section after a signal should be long enough for the train that may enter it. If a train stops while its rear still occupies a junction, the signal has protected the wrong place. Leave a full train length between the waiting signal and the conflict whenever the layout allows it.
On a two-track corridor, make direction clear and consistent. On a single-track corridor, create deliberate passing places and protect their entrances. Do not rely on a train finding a passing opportunity that the track layout does not provide.
Junction design priorities
- Keep the main conflict area short.
- Give waiting trains space before the junction.
- Avoid station platforms whose exits immediately merge into a blocked junction.
- Separate frequent local services from slow freight where traffic justifies it.
- Make every intended movement physically possible before optimizing priority.
Diagnose a stopped train
Follow the route forward from the train. Find the first occupied section, conflicting movement or unreachable path. Then check backward: is the waiting train blocking another junction or platform?
| Symptom | First inspection |
|---|---|
| Two trains face each other | Direction and passing-space design |
| Station exit remains blocked | Junction clearance and downstream section length |
| One branch rarely moves | Conflict frequency and route priority |
| Train reports no path | Track connection, terminal assignment and signal direction |
| Corridor slows after adding trains | Number and length of usable sections |
A safe rebuilding method
Pause, save and simplify. Remove the least essential branch or signal from the problem area, verify one movement, then restore other movements one by one. Watch complete cycles rather than a single train. A layout that clears once can still fail when vehicles return in a different order.
When the answer is more track
Signals improve use of existing track, but they cannot create unlimited capacity. Add a passing track, longer approach or separate corridor when trains repeatedly wait even though the signaling logic is clear. Infrastructure expansion should follow observed queues, not precede them.