Signal System of Canada and the U.S.

Signal System of Canada and the U.S.

The U.S. and Canada can be said to possess one signal system because of the many points of commonality in their signal codes. Portions of the signal code aspects and indications are also found in several systems in the Americas and in Australia. Because of the many common features it may seem a simple matter to review these signals; however, the substantial similarity is occasionally skewed by differences, and a review of Canadian and U.S. signals can be a complicated matter.

The Canadian Uniform Code of Operating Rules (UCOR) (BOTC 1961 TISRPS), and the Association of American Railroad Standard Code of Operating Rules (SCOR) (AAR 1965 TISRPS -excepted where noted for joint BOTC and AAR). The numbering and content of rules is similar: both codes begin with Rule #281 (for clear signals) and end with #293 (stop signals). But the U.S. pattern has several rules or sub-rules lacking in Canada, and Canada has some that are not found in the U.S.; one shared rule number contains divergent contents.

Despite differences an overview of the two systems in tandem is possible. However, if such a review follows the rules in sequence an anomaly becomes evident: the color pattern breaks down and contradictory groups of colors indications are placed together. The Canadian National Railway (CNR) offers an alternative pattern that ignores numbers but preserves color patterns and categories of indications (CNR 1975). CNR has arranged signal indications into categories of clear signals, approach signals in which the speed indication comes before the word approach, approach signals in which the word approach comes before the speed indication, and stop signals.

This method creates a coordinated color pattern: the left-hand side - or clear segment - contains signals with green and green/red signal lights; the second segment contains signals with yellow and yellow/red lights; the third with yellow/green and some yellow/green /red and the fourth, those containing red-only messages (though plates with qualifying messages may be present in some situations).

In essence, UCOR and SCOR display simple messages; green indicates clear, yellow indicates approach (caution) and red means halt (with qualification in Canada). But many signals are multi-position and this creates more complex messages; for example, a red lamp may be found with a clear indication: the top signal lamp will be green but a second and even third lamp can be red without altering the clear meaning. A red/green indication remains in the clear category but has a more restrictive character. 'A "medium clear signal" (RGR) requires a train crew to proceed at the medium speed while traversing turnouts or while within an interlocking arrangement; RRG is yet more restrictive.

Approach signals (speed listed before approach) are Y or YR. Y before R is less restrictive while R before Y indicates greater restriction. Nearly all are prefixed with a "be prepared to xxxx at the next signal." Approach/speed signals are YG and sometimes YGR and lack the "be prepared" preface. Stop signals can exhibit more complexity than the simple word may indicate. In the U.S. the stop signal has one, two, or three lights for an absolute stop. The Canadian absolute stop requires two lamps; Canada single aspect red lights and staggered two-aspect lamps are permissive stop or stop and proceed signal. There are also grade, and station protection variant forms of the stop signal. Appendix II provides further details and a chart for Canada and the U.S.