Why can't I clear a signal sometimes?

The interlocking refuses any move that could cause a collision: points set the wrong way, the platform still occupied, or a crossed route needing the junction while another train is on it. The message under the picture says which.

Why do the points take time to move?

They are moved by a heavy motor and checked by a detector before any signal can clear, so that a train is never sent over points that are half-way between positions.

Signal Box

Run a station throat from the signal box. Two lines come in, two platforms go out, and the points decide which leads where. A crossed route blocks the whole junction, so you choose who goes first, throw the points early and keep the expresses moving. Six shifts with more trains and less time between them.

Strategy
Free, plays in your browser
Mouse, touch or keyboard
Added 10 November 2026
#signalbox
#railway
#points
#junction
#scheduling
#timetable

Signal Box

0% · Getting ready

Watch a 20-second trailer

A real run of the game, recorded with captions and no sound.

How to play

Trains arrive on line A (top) or line B (bottom) and stop at a red signal. Each has a platform number on it. Press the points button (key 1) to switch between straight (A to 1, B to 2) and crossed (A to 2, B to 1), then press Clear signal A or B (keys 2 and 3).
The interlocking stops any dangerous move: the signal will not clear if the points are the wrong way, the platform is full, or a crossed route would share the junction with another train. The points take three seconds to move and lock while a train is on them.
Get every train through with a mean delay under the limit shown. Red trains are expresses and should not wait long. Use fast-forward in the quiet moments.

Controls: mouse, touch or keyboard. Made by CalcoTools.

Tips and strategy

Throw the points for the next train while the last one is still on the platform, so it is not the points that it waits for.
Two straight routes can run side by side, so when A wants platform 1 and B wants platform 2, let both go together.
An express that has been waiting longest should go first, even if it means throwing the points the other way.

FAQ

Why can't I clear a signal sometimes?: The interlocking refuses any move that could cause a collision: points set the wrong way, the platform still occupied, or a crossed route needing the junction while another train is on it. The message under the picture says which.
Why do the points take time to move?: They are moved by a heavy motor and checked by a detector before any signal can clear, so that a train is never sent over points that are half-way between positions.

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