Young Curly Blonde Girl Changes The Railroad Switch On The Railway Track

Run-off points are used to protect main lines from stray or runaway railroad cars or from trains passing signals set at danger. In these cases, vehicles would otherwise roll onto and obstruct a main line (sometimes known as fouling) and cause an accident. Depending on the situation in which they are used, run-off points are referred to either as trap points or catch points. Derailers are another device used for the same purpose.
Catch points are installed on the running line itself, where the railway climbs at a steep gradient. They are used to prevent runaway vehicles colliding with another train further down the slope. In some cases, catch points lead into a sand drag to safely stop the runaway vehicle, which may be travelling at some speed. Catch points are usually held in the 'derail' position by a spring. They can be set to allow a train to pass safely in the downhill direction using a lever or other mechanism to override the spring for a short time.
Catch points originate from the days of the 'unfitted' goods train. These trains did not have a mechanism in place to automatically brake runaway cars. Catch points were therefore required to stop the rear portion of a train that had become divided, although they would also stop vehicles that had run away for any other reason. Now that trains are all 'fitted', catch points are mostly obsolete.
Similar to catch points, trap points are provided at the exit from a siding or where a goods line joins a line that may be used by passenger trains. Unless they have been specifically set to allow traffic to pass onto the main line, the trap points will direct any approaching vehicle away from the main line. This may simply result in the vehicle being derailed, but in some cases a sand drag is used, especially where the vehicle is likely to be a runaway travelling at speed due to a slope.