UK Safety Systems: TPWS (Train Sim World | UK safety systems tutorial)

[@Freddy_507]

Thank you very much again for this great tutorial and wonderful explanations ;)

[@tygerways6615]

Thank you for the friendly feedback! I am happy that you liked the video!

[@SireMoon]

44:35 - Closeup on (presumable) track circuit installations, track circuits discussed The device between the rails you are describing is related to track circuits but not in the way you thought. There are track circuits which work as you describe but this device is not to do with that. This device is called an impedance bond (or a "spider" to railway staff) and is found (in the UK anyway) on third rail lines. As you know conventional track circuits divide the track up into electrical blocks and at the boundary of each block there are insulated rail joints to separate them. DC electrified lines use DC traction current (obviously!) and therefore use AC conventional track circuits to mitigate the risk of the DC traction return current in the rails interfering with the track circuits. Where conventional AC track circuits are used on third rail lines in the UK, an impedance bond is placed at each track circuit insulated joint and it allows the return DC traction current to pass across the track circuit joint but blocks the AC track circuit current from passing across. On a general note I'm belatedly getting into German routes in TSW and find your videos on signals, PZB and LZB very helpful and interesting.

[@tygerways6615]

Awesome! Thank you very much for this very interesting information! I have read about impedance bonds but didn't know what they looked like. We live and learn. :)

[@SireMoon]

@@tygerways6615 You're very welcome

[@1992wcwood]

Another interesting fact I read tonight before I watched this. Also related to third rail lines. You mentioned AWS magnets being painted either yellow or green. I read that the yellow ones use a standard magnet strength and are in place on diesel and overhead AC lines. The green ones use a stronger magnet to overcome possible interference from the live third rail. I always wondered why there's green ones... Also second to Sire Moon. You're videos are awesome. Thank you for doing them.

[@tygerways6615]

@@1992wcwood Thank you very much! For the friendly feedback as well as for the extremely valuable piece of information about the color of the AWS magnets!

[@user-xi8fo6vv1c]

Thank you for your video about TPWS So how much speed should I kept before the TPWS OSS transponders, to ensure that I won't get a penalty brake

[@tygerways6615]

Very good question, that cannot be answered easily, unfortunately! The "set speed" for the TPWS OSS loops depends on the location and its parameters (line speed, gradient, distance from the loop to the signal, etc). You can find the information that "generally" the set speed is 46 mph for passenger (36.5 mph for freight) trains, if the OSS loop is protecting a red signal and 12.5 mph if it is protecting a buffer block. The setting of OSS loops that protect permanent speed restrictions (PSR) is a matter of discussion even among real life drivers. Since the set speed is determined by the distance between the transponders, you could estimate the set speed for a given OSS loop by measuring the distance and doing the math (while 46 mph for passenger trains corresponding to a spacing of 20 meters, measured from leading edge to leading edge).