Tech stuff for the Valley Inturban – The Indusi Signaling System A?ai??i??ai??? how it works (Part 2)

The Details

Here I will describe how the detection of the magnets influences the train. The details vary a little depending on which type of Indusi equipment is used, here I will cover the properties of the PZBAi??Ai??90 for Zugart (train type) “O” (Obere Klasse: Upper class, i.e. fast passenger trains)

If any test fails (i.e. driver does not react appropriately or speed is beyond the limit), an emergency braking occurs.

1000 Hz magnet

The 1000 Hz magnet is usually placed with the distant signal, i.e. some 1000Ai??Ai??m before the main signal and some 1200 m before the danger point protected by that main signal. That danger point could be e.g. a clear-of-points marker, a crossing etc.

If the 1000Ai??Ai??Hz magnet is detected, the driver has four seconds to acknowledge by pressing the “Indusi Wachsam” (Indusi on alert) button. Then, the train’s speed is constantly compared against a limit, which starts at 165Ai??Ai??km/h and within the next 23 seconds is lowered to 85Ai??Ai??km/h (brown curve).

If the train does not stop (e.g. because of a halt or platform), and no 500Ai??Ai??Hz magnet is detected, the limit is maintained at 85Ai??Ai??km/h until 1250Ai??Ai??m after the 1000Ai??Ai??Hz magnet. At 700Ai??Ai??m after the 1000Ai??Ai??Hz magnet, the driver can press the “Indusi frei” (Indusi release) button to end the speed restriction, e.g. if he can see that the signal in advance has changed to clear. This is called “to release oneself from the (1000Ai??Ai??Hz) speed control”.

However, if the driver has released himself from the 1000Ai??Ai??Hz speed restriction, and then a 500Ai??Ai??Hz magnet is detected within 1250Ai??Ai??m after the 1000Ai??Ai??Hz magnet, indicating that the signal is still at stop, the driver probably has wrongly released himself from the speed control and gets – an emergency braking, what else?

500 Hz magnet

The 500Ai??Ai??Hz magnet is placed at some 150 to 250 m before the main signal, or about 450Ai??Ai??m before the danger point.

If a 500 Hz magnet is detected, a speed limit of 65Ai??Ai??km/h is applied and lowered to 45Ai??Ai??km/h within the next 153Ai??Ai??m, then stays at 45Ai??Ai??km/h for the next 250Ai??Ai??m (red curve). Release from that limit is not possible.

Note that if the restriction to 45Ai??Ai??km/h has ended 403Ai??Ai??m (153Ai??Ai??m+250Ai??Ai??m) after the 500Ai??Ai??Hz magnet, the restriction to 85Ai??Ai??km/h imposed by the 1000Ai??Ai??Hz magnet may still be active.

2000 Hz magnet

The 2000Ai??Ai??Hz magnet is placed with the main signal, or at some 200Ai??Ai??m (down to 50Ai??Ai??m or up to 400Ai??Ai??m in special cases) before the danger point.

A detection of a 2000Ai??Ai??Hz magnet always causes an emergency braking. If our driver made it until here (without emergency braking), his speed is at maximum 45Ai??Ai??km/h, so the braking should get him to stop before the danger point, even if he chooses to pass the red signal, so even a SPAD¹ shouldn’t cause an accident.

Intermediate halt

If the train halts, or travels for at least 15 seconds at less than 10Ai??Ai??km/h, while either of the 1000Ai??Ai??Hz or 500Ai??Ai??Hz speed control is still active, the applicable speed limit is lowered by 20Ai??Ai??km/h, we say it becomes restrictive. A restrictive 500Ai??Ai??Hz-induced speed limit is maintained for the next 200Ai??Ai??m, if the restriction is activated until 100Ai??Ai??m after the 500Ai??Ai??Hz magnet, for the next 250Ai??Ai??m otherwise. This is to ensure that a train which has halted before the main signal, e.g. at a platform stop, can only accelerate to a speed that still permits the train to stop short of the danger point, should it detect the 2000Ai??Ai??Hz magnet, i.e. it had run the red signal.

http://railforthevalley.wordpress.com/2009/06/26/tech-stuff-for-the-valley-inturban-the-indusi-signaling-system-how-it-works-part-1/