Abstract
Track circuit uses rail as a part of the circuit. The purposes of the track ciruit are 1) to detect the train, 2) to transmit signal to the train, and 3) to detect the rail break. There are two types in the track circuit. One adopts insulation joint at the end of the circuit, and the other one is jointless. The insulation joint demands a lot of effort to maintain and control. Furthermore it costs extremely, and it has an insulation material that becomes one of the weak points of the rail track. There are some methods to make a jointless track circuit, but it has several problems. The biggest one is that the border of the track circuits becomes fuzzy. The next one is the interference of plural track circuit signals. Nevertheless jointless track circuit has a big priority. First it does not demand an insulation joint and impedance bonds. Second it is very easy to divide.
Jointless track circuits are adopted in the area of the sharp curve where impossible to install insulation joints on the Shinkansen line. Also several conventional lines and private railways adopt this system. Furthermore several European high speed train system also use jointless track circuit. In JR, short distance track circuit for level crossing control is jointless, but normal track circuit has an insulation joint, because there is a law restriction of track circuits border ambiguity. To solve the problem, the author had worked out simple jointless track circuit only with induction coils, which border characteristic is very excellent. Furthermore it does not have a strong frequency characteristic that it can be applied to any kinds of frequencies. In this paper, new type of jointless track circuit is proposed, it is theoretically analyzed, and basic experiments had succeeded that they are reported.
