Every train carries a recorder that writes down speed, position, and every control the driver moves, and it is downloaded after any incident and read like a flight recorder. Ours show a service brake application at milepost 41 on the last down service, on every unit, from a handle the driver did not move.
I am a fleet engineer and the on train monitoring recorders on about sixty units are my responsibility.
What the recorder captures, because there is no arguing with it afterwards.
Every unit has one. It samples speed, distance, the brake pipe and cylinder pressures, the position of the driver's controller, the state of the doors, the AWS and the vigilance device, and it timestamps all of it against GPS. It is the same idea as an aircraft's recorder and it is used the same way: after any incident, the first thing anybody does is download it.
Drivers know that. A brake application in the log is a brake application, and a driver who says they did not make one is contradicted by a box that has no reason to lie.
On the last down service through a particular stretch, every night, the recorder logs a step one service brake application at milepost 41 and a release about four seconds later.
The controller position channel shows the handle moving to brake and back.
The driver's channel shows nobody pressed anything, because the vigilance and the AWS are separate channels and they are quiet.
It is every unit that works that diagram. Twenty three different units in the last year, three different classes of train, and it is in the log of every one of them on the night they did it.
The obvious answer is that the drivers are doing it and not remembering, and that was my answer for a long time.
Milepost 41 is on a straight, on a falling gradient of one in two hundred, with the next signal two miles away. There is no reason to brake there and no driver has ever said they did.
I have spoken to eleven of them. Two said they felt it. Both described the same thing: a light check, as if somebody had touched the brake, at a place where they had not.
One said she looked down at the handle and it was moving.
What has been examined.
The recorders themselves, on four units, downloaded and bench tested, and the brake controller wiring checked for a fault that could report a movement that did not happen.
A recorder can misreport a position. What it cannot do is misreport the brake cylinder pressure, because that is a transducer on the cylinder, and the cylinder pressure rises. The brake was applied. Iron touched steel and the train slowed by about two miles an hour.
The track. The permanent way have walked it and there is nothing at milepost 41 but a milepost.
Interference. Any radio, signalling or traction return path effect would show at other times and on other services, and it does not. It is the last down service, and only that one.
What I did in 2023 that was not on any work order.
I rode it. In the cab, with the driver's permission and the traction inspector's, on a Tuesday in March.
The driver was a man I have known for years and he drove it like he drives everything, which is very well.
At milepost 41 the brake handle moved to step one under his hand, and he said, quite quietly, there it is, and it moved back.
His hand was resting on it the way a driver's hand rests on a controller. He did not move it. I was standing behind him looking at his hand and I would say that in an inquiry.
What has been done about it officially.
It is a recorded anomaly on the fleet with a reference number. The safety case position, which I helped draft and which I agree with, is that an uncommanded step one application on a falling gradient with two miles to the next signal poses no risk, that the brake system responds correctly to the demand, and that the fleet remains fit for service.
That is true. A brake that applies when nobody asks it to is a nuisance. A brake that does not apply when somebody does is the thing that kills people, and ours have never once done that.
What I do.
I download the recorders on the schedule and the milepost 41 events go into a spreadsheet nobody has asked me for.
I have stopped riding that service. The one trip was enough and I have a reason for that which is not on any form.
The recorder logs door state. In the cab of that unit at milepost 41, with the driver's hand on the handle and the brake coming on, the recorder also logged the cab door on the driver's side as open for two seconds, and the cab door on the driver's side is beside my left elbow, and it was shut, and I had been leaning on it.