Train Signals

Block=

Path=

Block and Path Signals are structures that can be placed on Railways to control the movement of trains and to prevent collisions.

Construction
Both types of train signals can only be built on the joints of constructed Railway tracks and will automatically snap to them. The forward direction of the signal is determined by which side of the joint is targeted. An Arrow also indicates the forward direction.

Up to 2 signals facing opposite directions can be placed on each track joint.

Usage
Signals divide the track into blocks, which is a section of track bounded by other signals. Blocks have to have an entry signal as well as an exit signal. All entry signals to a given block have to be of the same type, either Block or Path. Path Signals can't be used as a terminal signal for other Path Signals.

Block Signals only communicate with the following (exit) signal about the current block's status. Path Signals ensure trains can enter the block and exit through a following, free Block Signal, therefore considering both the current and following block's statuses. This means that Path Signals ensure trains will not have to wait anywhere inside the block.

A block is considered occupied if a part of a train is present anywhere within it. Path Signals subdivide a block into paths, and treat them as individual subblocks while additionally checking the exit of the path to ensure a train won't stop anywhere within the block. This allows multiple trains to pass through the same block at the same time as long as their paths don't intersect each other. All trains are prevented from entering the block following a Block Signal (or a specific path following a Path Signal) if another train is occupying it.

Pathfinding is done by Locomotives, not signals. Path Signals reserve paths based on information received from incoming trains. Signals cannot change the paths trains have chosen, they can only tell the trains whether they can proceed on their path or not. This renders rail stackers impossible to build.

States

 * Green
 * Block Clear (Block Signal)
 * Path Approved (Path Signal)
 * Red
 * Block Occupied
 * Waiting for Path Reservation (Path Signal)
 * Error (treated as red by trains)
 * Invalid Signal
 * Signal has missing connections
 * The signal is placed on the very end of a Railway, leading nowhere
 * Block has no exit signal
 * Block has conflicting entry signal types
 * All entry signals have to be either Block or Path, this does not apply to exit signals
 * Path block cannot contain stations
 * Signal loops into itself
 * This error means the signal failed to divide a block, even when no loops are present. It can occur when, for example, two unconnected tracks are to close to each other and a signal is placed on one of them.

Trivia

 * Train signals were originally planned for Update 6.

External link

 * Train Signal Guide by TotalXclipse on YouTube

History

 * Patch 0.5.2.1:
 * Stations cannot be placed inside Path blocks anymore, Path Signals now give a proper error message if a Station is found inside a block
 * Short blocks, about 75% the size of a Freight Car, should now work with Path Signals
 * Fixed Path Signals placed right after a station being incorrectly reserved by trains going to the station
 * Patch 0.5.1.13: Multiple fixes related to issues with Path Signals and Block Signals
 * Patch 0.5.1.11: Potential fix for multiblock reservation issues for train signals
 * Patch 0.5.1.4:
 * Fixed a bug where trains docked at a Train Station could reserve Path Signals when saving and loading
 * Fixed a case where trains approaching Train Stations with a Path Signal right after the station would reserve the same Path Signal over and over
 * Patch 0.5.0.11: Added visual feedback for blocks when placing down signals
 * Patch 0.5.0.0: Introduced