[Beeyar Wunby]

It's surprisingly easy to do this. On most multiple units in the UK if you have the desk energised and the train is standing still, you can release the brake and put the Master Controller into neutral. If there's any gradient the train will eventually start to roll.

There is a safety system to deal with this....but there's a catch. At around about 6 mph, depending on the traction unit, a relay operates the Speed Sense function. This is effectively a decision speed where certain criteria must be met, otherwise the Emergency Brake will be applied. In modern railway practice it's not allowed for the master controller to be in neutral whilst the train is under way, so once the train reaches 6 ish mph the SS relay operates and the train is brought to a stand.

Great - except that after a timeout period the Emergency Brake will release. If the train is still standing on a gradient then this process will happen again ,and keep on happening untiil something occurs to stop it.

As you would expect, the Rulebook is quite clear about preventing this. The driver must always 'secure the cab' before leaving it. This requires the brake to be put into Full Sevice, Master Switch to neutral, DRA applied if it's a passenger train, and the door locked so that no unauthorised person can get in.

Actually this nearly happened to me once. I was instructed to take my unit into a sidings and 'pump up' another one. The other unit had been 'cut out' all night and all the air had leaked out. This is quite safe because modern EMUs/DMUs have a spring operated Parking Brake which operates when the Brake Cylinder Reservoir air pressure drops, and then disengages automatically when the air pressure returns. Anyhow, when I coupled up to the dead unit much of my air transferred into it. This pressure drop caused my Emergency Brake to apply (as expected). At this point my head was full of technical issues and I left the brake controller in my cab in the off position. This was masked by the fact that the brake pressure gauge was showing a full emergency application. I then got out of my train and got into the cab facing me on the other train to monitor how it was pumping and see if I could get the pantograph to raise.

About 5 minutes later I had moved 2 coaches further down the dead train and was trying to tickle the auxilliary convertor into life when I heard a clunk and a loud long hiss. It was the brakes on the whole train releasing from the 5 bar Emergency state. This was because both units' Main Reservoir Pipes were now filled up and so the safety system allowed the train brakes to be released.

I hammered through the train and hurled myself onto the nearest Emergency Brake Plunger. Fortunately the train hadn't actually started to roll. Also this was off the mainline in the safety of a sidings where I had permission to move under my own authority. But it was still luck rather than good judgement which stopped an incident.

That's what happens when you let the technical needs distract you from good operating practice.

Hope this helps, BW