Learn how Train Simulator Classic signals, blocks and aspects work, what red and yellow mean, and how to handle signals that will not clear.
In Train Simulator Classic, signals protect blocks and junction routes. The dispatcher sets a path, then each signal displays an aspect—such as green, yellow or red—according to track occupancy, points and the next signal. Obey the route's real-world signalling rules: colours, semaphores and cab warnings vary by country and add-on.
What do Train Simulator Classic signal colours mean?
Signal colours are route-specific, but many British routes use the familiar three- or four-aspect colour-light system. This table gives the normal interpretation; specialised, historic and non-UK routes may work differently.
| Aspect | Normal meaning | Driving action |
|---|---|---|
| Green | Proceed; the route is clear to the next signal under the normal sequence. | Continue while obeying speed boards and preparing to observe the next signal. |
| Double yellow | Preliminary caution; the next signal is normally single yellow. | Begin reducing speed and plan to stop at the red signal beyond the next one. |
| Single yellow | Caution; the next main signal is normally red. | Brake early enough to stop before the next signal. |
| Red | Danger or stop. | Stop before the signal unless the dispatcher explicitly authorises you to pass it. |
Flashing yellow sequences usually indicate a diverging route has been set and that a junction signal ahead will display the relevant route indication. They do not cancel the turnout speed restriction. A mistake we see constantly is treating green as permission to ignore speed boards; a clear signal grants movement authority, not unlimited speed.
Semaphore routes use arm position as well as colour. A horizontal red stop arm means danger, while an upper-quadrant arm raised or a lower-quadrant arm lowered means clear. Yellow fishtail distant signals provide advance warning. German, North American and other routes can use speed- or route-signalling principles that cannot be translated directly into the British table, so consult the route manual.
Cab warning systems are separate from the visible aspect. On AWS-equipped routes, a warning horn normally requires acknowledgement with Q; failing to acknowledge it can produce a brake demand. Our keyboard-control reference explains the AWS and signal-permission commands. Other safety systems may have route-specific controls.
How does the simulator decide which aspect to show?
Train Simulator Classic combines signal scripts, linked track sections and the scenario dispatcher to determine each aspect. The result depends on several conditions:
- Block occupancy: a train occupying the protected section normally keeps the entrance signal at red.
- Route setting: points must be aligned and the path through a junction must be available.
- The signal ahead: yellow and double-yellow aspects provide the required warning before a red signal.
- Conflicting movements: an AI train may already have a junction or platform route reserved.
- Special signal logic: approach control, permissive working, shunting aspects and route indicators can alter the normal sequence.
A signal returning to red after the front of your train passes is normal: it is protecting your train from following traffic. Green only confirms authority to the next relevant signal; it does not guarantee a clear route for the rest of the scenario.
Timetabled and standard scenarios also use paths, priorities and AI instructions. Our explanation of dispatcher paths, signal blocks and AI traffic in scenarios shows why one service may be held while another crosses ahead.
What should I do at a yellow or red signal?
At yellow, brake on the assumption that the next main signal will be red; at red, stop with the front of the locomotive short of the signal post.
- Read the aspect early. Use the line-side signal as the authority and the driving HUD as supporting information. At double yellow, start planning; at single yellow, make a definite service-brake application.
- Stop before red. Do not creep beyond the post while waiting for it to clear. Passing without authority is a signal passed at danger, or SPAD, and may trigger emergency braking or end the scenario.
- Allow the route to clear. The dispatcher may be waiting for an AI train, a departure time or an approaching-train trigger.
- Request permission only when necessary. If the signal remains red and the scenario expects you to continue, use the standard
Tabcommand. Proceed only if the dispatcher grants permission or a valid subsidiary aspect authorises the movement. - Pass cautiously when authorised. Permission to pass red is not the same as a clear aspect. Travel at a speed that lets you stop short of an obstruction, incorrectly set points or another train.
For the wider braking technique behind this procedure, see our practical guide to observing signals and controlling a train.
Why will a red signal not clear?
A persistent red signal usually means the block or route is unavailable, although approach control and scenario faults can produce similar symptoms.
- Another train has the route: wait for the AI movement to clear the block or junction. Requesting permission will normally be denied while the conflict remains.
- Approach control is active: some junction and platform signals stay red until your train approaches at a controlled speed. Continue towards the signal prepared to stop; it may then clear to a restrictive aspect.
- You are early: a timetabled scenario may hold the route until the booked departure time or until another service has passed.
- A scenario instruction is incomplete: finish the station stop, coupling task or reversal movement exactly as shown. Missing a reversal marker can leave the dispatcher expecting the wrong direction of travel.
- The route is not set: automatic points are normally controlled by the dispatcher, while manual points may need setting in free-roam operation. Follow our instructions for checking and changing points safely rather than forcing a dispatcher-controlled junction.
- The scenario or signal script has failed: if only one scenario is affected, restart it from the beginning because saved AI timing or scripted signalling can occasionally resume incorrectly. If every scenario fails at the same location, check the route and its required add-ons for missing or damaged content.
If Tab returns permission denied, remain stopped. Repeated requests do not make an occupied or conflicting route safe.
Why do the HUD and line-side signal disagree?
The driving HUD simplifies signalling information and may not represent every repeater, shunting aspect, junction indicator or custom signal script correctly. Complex junction links and reversing movements can also cause the displayed next signal to change unexpectedly.
Treat the physical line-side signal—and any route-defined cab signalling—as the governing indication. If a signal is dark, missing or plainly inconsistent, stop rather than assuming the HUD grants authority, then use the dispatcher permission command only if the scenario permits it.