An electrical circuit that includes an insulated section of track. A train occupying the track will complete the circuit by connecting the two rails together via its wheels and axles thus signaling the trains occupation of that section of track. Track circuits are designed to detect the presence or absence of a train.
" class="glossaryLink ">轨道电路闭塞-对绝对闭塞系统的一种修改，在整个系统中采用轨道电路。只要线路畅通，火车就可以开往下一站Visual indication passed to a train driver to advise the speed, direction or route of the train. There are almost as many types of signals as there are railways but they fall into the following main categories:1) handsignals - used mainly where there are no fixed signals or where the fixed signalling has failed. 2) semaphore signals - a fixed lineside signal where the stop indication is displayed as a horizontally positioned arm and proceed as a 45º or vertical arm. 3) colour light signal - a fixed lineside signal showing light indications to drivers. 4) cab signals - where the indications are displayed in the driver's cab.
" class="glossaryLink ">信号再加上信号以外的重叠部分
