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There are two main types of signaling aspect systems found in North America, speed signaling and weak route signaling. [citation needed] Speed signaling transmits information regarding how fast the train is permitted to be going in the upcoming segment of track; weak route signaling transmits information related to the route a train will be taking through a junction, and it is incumbent upon ...
A rail break between the insulated rail joint and the track circuit feed wiring would not be detected. Failure modes that result in an incorrect "track clear" signal (known usually in North America as a "false clear") may allow a train to enter an occupied block, creating the risk of a collision. Wheel scale and short trains may also be a problem.
Treger token system posts at Ogaryovo railway station, Vologda Oblast, Russia. Until the late 20th century, the token system was standard on British single-track lines and it still remains on a number of lines there as well as elsewhere, such as the line between Girvan and Stranraer in south west Scotland.
These take the form of routing decisions at controlled points that authorize a train to proceed or stop. Local signaling logic will ultimately determine the exact signal to display based on track occupancy status ahead and the exact route the train needs to take, so the only input required from the CTC system amounts to the go, no-go instruction.
Bidirectional signalling is the provision of signalling that allows one or more tracks on a multiple track railway to be operated in either direction, whether for regular or emergency use. Bidirectional signalling intended for regular use will generally allow traffic to flow at similarly high frequency in one or other direction.
Railway signalling (BE), or railroad signaling (AE), is a system used to control the movement of railway traffic. Trains move on fixed rails , making them uniquely susceptible to collision . This susceptibility is exacerbated by the enormous weight and inertia of a train, which makes it difficult to quickly stop when encountering an obstacle.
The US and Canada departed from UK practice wherein a semaphore blade is devoted to each route (Route Signaling). General North American practice is to group routes by speeds and use a single blade for, say, "medium speed" regardless of the number of routes involved (Speed Signaling). The primary exception to this situation is in the field of ...
In double track territory one may find two signals mounted side by side on a bracket which itself is mounted on a post. The left hand signal then controls the left-hand track, and the right signal the right-hand track. A gantry or signal bridge may also be used. This consists of a platform extending over the tracks; the signals are mounted on ...