"litz"
Regular trains (both freight and passenger) have been able to do this for decades ... either an actual brakeman at the back end of the train looking at a gauge, or an electronic device reporting brake pressure telemetry.
Either way, the concept is simple : if you reduce brake pipe pressure at the front end of the train, you'd better see the same pressure reduction at the back end of the train. If you don't, something is wrong.
Actually it's not that simple. The pressure along the length of the brake pipe will very until it equalizes after stopping the release of air. The pressure will be the lowest at the point ware the air is escaping from the train line. On a freight train the brakes will apply on the car behind the locomotive 1st then the 2nd car then the 3rd etc until the entire length brake pipe has an equal pressure.
WMATA cars have an electro pneumatic brake system on them that reduces and or increases the train line brake pipe pressure equally over the entire length of the train to apply or release the brakes simultaneously.
Regular trains (both freight and passenger) have been able to do this for decades ... either an actual brakeman at the back end of the train looking at a gauge, or an electronic device reporting brake pressure telemetry.
Either way, the concept is simple : if you reduce brake pipe pressure at the front end of the train, you'd better see the same pressure reduction at the back end of the train. If you don't, something is wrong.
Actually it's not that simple. The pressure along the length of the brake pipe will very until it equalizes after stopping the release of air. The pressure will be the lowest at the point ware the air is escaping from the train line. On a freight train the brakes will apply on the car behind the locomotive 1st then the 2nd car then the 3rd etc until the entire length brake pipe has an equal pressure.
WMATA cars have an electro pneumatic brake system on them that reduces and or increases the train line brake pipe pressure equally over the entire length of the train to apply or release the brakes simultaneously.
John in the sand box of Maryland's eastern shore.
