Not if the risks it introduces outweigh those it mitigates.
Perhaps it is a failure of imagination, but I'm not sure what safety risks are introduced by introducing diverse means of tripping brakes in hauled trains in an emergency, and/or installing monitoring of brake isolation systems.
But the railway wasn't making no attempt to protect against faults. It had a well-proven system in place that was designed to protect against all brake discontinuity faults. And as you say, obtaining total protection is often impractical, as proved to be the case.
This is not the first incident caused by a mistake in brake isolation. This was one of the most high profile, but there have been SPADs caused by brake isolation cocks being closed incorrectly, including
this RSSB report in 2020 on a freight train at Crofton West junction.
At around 09:54 hrs, the driver of a freight train applied the brakes on the approach to a red signal at Hare Park Junction, near Wakefield but was unable to stop. The train continued with the brakes applied and passed a second red signal, about 2200 metres later, that was protecting Crofton West Junction. The train came to a stop 250 metres beyond the junction. A passenger train that was approaching Crofton West Junction on a conflicting route was stopped by signals when it was approximately 3 km away.
There was also the runaway Class 66 incident at
East Didsbury back in 2007 that resulting in a locomotive yo-yo-ing through a worksite with no lights or noise warning, which would have been prevented had mistakes in air brake isolation had been avoided or had been detected before the later coupling failure.
Immediate cause, causal and contributory factors, underlying causes
7 The immediate cause of the incident was that the rearmost wagon drawhook broke at a time when the train was on an upward gradient and when the trailing locomotive had no air supply available in its air reservoirs to apply the brakes.
8 The following causal factors were identified:
- a sudden, larger than recently experienced tensile load was applied to the drawhook;
- the drawhook had a pre-existing fatigue crack below the gedge slot;
- the Assist Failed Train (AFT) cock on the trailing class 66 locomotive was not opened when train 6L22 left Crewe;
- residual air within the trailing locomotive’s reservoirs was used up on the journey between Crewe and the incident location; and
- the class 66 locomotive design requires the AFT cock to be manually opened to allow the locomotive to be safely dead-hauled on the back of a single piped train.
I think there are probably others but these are the ones that came to mind immediately, I'd say brake isolation mistakes and failures are probably a significant portion of the entire remaining non-suicide risk on the railway.
I am not saying it couldn't be done. I am saying that, just as with your suggestion to prove the brake lever, there was no reason to do it.
As one of my old bosses used to say, just because you can do something, doesn't mean you should do it. There needs to be a reason to do it, particularly if it is going to cost money or make the system more complex and therefore less reliable.
Most safety-case industries have increasingly deprecated so-called 'procedural' controls as a means of guaranteeing safety.
Even the railway has moved in this direction with increasing emphasis on automatic train detection and interlocking, as well as on various train protection mechanisms.
By contrast the air brake remains aloof from such changes.
The changes necessary to the sleeper stock to eliminate this source of risk are smaller than in the freight train cases (which are now the vast majority of trains in which traditional air brakes are used), because the necessary control specification is already established and connectors with the necessary pins already provided.
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