Following signal indications

There is a risk of a serious train collision or derailment if rail signals are not consistently recognized and followed.

Added to the Watchlist on 16 August 2010

Source: Ray Thibaut, reprinted with permission

Photo: Ray Thibaut, with permission


Since 2002, there has been an average of 111 occurrences per year in which a signal indication was misidentified, misinterpreted or not immediately recognized. When this type of occurrence results in a train collision or derailment, there can be significant risk to the public and the environment.

Since 1911, the railway industry in Canada has relied on centralized traffic control (CTC), a system of visual signals, to control traffic on a significant portion of its network—currently more than 44,000 kilometres of track.2 The CTC system provides train crews with a series of signal indications requiring actions relative to the signal displayed. The signal indications convey information such as operating speed and the operating limits within which the train is permitted to travel. Train crews must be familiar with the signal indications and must control their trains accordingly.

If signal indications are not followed, the CTC system cannot ensure that trains on the same line are separated appropriately. CTC does not provide any warning that a train may be passing beyond a restricted location, nor does it provide automatic means to slow or stop a train before it passes a stop signal or other points of restriction.

To augment CTC safety measures, railways have adopted various other defence mechanisms to help prevent accidents, such as two-man crews, Canadian Rail Operating Rules, and general operating instructions. However, these defences are inadequate in situations where the train crew misinterprets or misperceives a signal indication or does not apply, or misapplies, an operating rule.

The Transportation Safety Board of Canada (TSB) has made a recommendation on this important issue. It recommended that:

The Department of Transport and the railway industry implement additional backup safety defences to help ensure that signal indications are consistently recognized and followed.
(Recommendation R00-04)

The following is a list of investigations where train signal misinterpretation/misperception was cited as a cause or contributing factor of an occurrence:


Further safety defences should be implemented to ensure that signal indications of operating speed or operating limits are consistently recognized and followed.

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  1. Source: TSB rail accident statistics.
  2. Source: 2011 Rail Trends, Railway Association of Canada.