The Little Train That Was Constipated

No pooping for you!


Sounds like the train was designed by a couple of engineers I’ve had to work with.

Gives an entire new dimension to the term “skid marks”.

I know how this would go in the USA if they just put up a sign. Half way up the mountain the train would stop, because the sign didn’t apply to multiple somebodies.

That’s a very stupid set up. Emergency systems should never be connected to other systems they are not meant to control. I’d like to know where the trains were made.

I don’t think this is altogether remarkable. Most trains are air braked. That air is provided by a compressor (or compressors) on the locomotive(s) or power car(s). The presence of a regular supply of compressed air on the train usually lends itself to use in axillary applications like opening and closing doors, windscreen wipers, air suspension, pressurising water supplies, and quite possibly flushing toilets.

There is usually a designed oversupply of compressed air, plenty of redundancy. If, however, there was a problem and one or more compressors (in a multiple compressor set up) was lost, a heavy axillary demand could lower the supply to a point where you’d have to start worrying about the braking system.

I’ve worked on trains that ran Westinghouse automatic air brake systems with a nominal brake pipe pressure of both 60 psi (425Kpa) and 70 psi (500Kpa). The Europeans run a similar, but fancier system called UIC. The compressors were usually set to keep the main air reservoir at least 150Kpa above the brake pipe, and we were taught that a 100Kpa ceiling above brake pipe was the comfortable minimum you’d want in service. You need a positive pressure difference to keep the brake pipe topped up, against either usage of the brakes, or leakage.

If the main reservoir air supply were to drop below the brake pipe pressure, it’s bad, but not the end of the world. The brakes would remain released until leakage lowered the brake pipe pressure enough to apply them. You’d probably be unable to release the brake, so you’d stop the train, apply the parking brake (which may also leak on, if you lose enough main reservoir air), and look for the problem. You can ‘wash out’ the Westinghouse direct release system, but in a low main reservoir situation, you probably wouldn’t have enough air to initiate enough releases to do so. The European UIC system is supposedly inexhaustible, and probably safer again in this scenario.

If you find your air supply restricted through loss of compressor capacity, yeah, you’d go looking to restrict and isolate those parasitic axillary devices like toilets. If you can’t maintain proper brake pipe pressure, you don’t move the train, and call for some assistance (like another train with a full set of compressors). The OP sounds to me like an unusual and adverse situation, handled properly by the crew of the train. Now if every train was locking off the toilets, then there’s a real problem, but this sounds like a one off. No problem, not unsafe, unless you’ve just consumed 12 beers and a curry.


Why or how is an air compressor needed to flush a toilet?
Gravity works fine for the toilets in my house. What is special about the ones on this train?

The ballistic trajectory achieved from the use of compressed air.

“Poops…in… SPAAAAACE”

The stain in Borlange comes mainly from the train.

Gravity may unleash the contents of the cistern into the bowl, but the water to refill the cistern has to come from somewhere. In most people’s houses, the water is pressurised from the main in the street. On a vehicle like a train, the water will be sitting in a tank, probably below floor level (to help with the centre of gravity), and has to be pressurised to move it up to the cistern. This is often done using the main reservoir air pressure.

That’s if the train toilet even has a cistern. Many just seem to get by with releasing a burst of water at pressure.

I don’t know if any of this applies to the OP. They may be using something else entirely, but still powered from the main reservoir air supply. It’s standard practice to do so. Given the brevity of the article, and the usual shortcomings in the reportage of technical railway practices by the general media, it’s impossible to say what really happened. It’s a “ha-ha, someone said toilet, OMG!” story, not an explanation of the actual circumstances.