| 摘要 |
<p>A model railway has a main loop of single track line on which trains can travel in either direction. There is a short length of double track with one track for each direction of travel. In addition, there is a section of three parallel tracks on which trains can travel in either direction. Switches placed on the track transmit signals to an electronic control circuit which determines which trains can travel and which trains must wait on the double or treble section. The circuit can deal with several trains and can be easily expanded to handle extra trains.</p> |
