The Truth About Leaves on the Line

As frequent travellers will be only too painfully aware, one of the staples of British rail journeys are the intercom announcements by train managers explaining why the service you're on is now delayed, redirected, terminated, side-lined, or whatever. These explanations can vary wildly from the sensibly mundane through to the slightly surreal ("bovine incursion"* is one of my favourites), to the almost completely cryptic.

For me the most recent example of the latter occurred during my last trip back from Oxford: the train manager haltingly explained that the driver had been forced to use the train's one-shot sand dispenser to come to a stop at a signal, as a result of which we were no longer able to run at full line speed and there would be a further delay when we did finally make it to the next station. I'd considered myself a fairly regular rail traveller and I thought I'd heard everything, but this was new to me. "One-shot sand dispenser?" What was that all about? It sounded technical, mysterious and possibly a bit dangerous, and the next day I did a bit of poking on the internet to try and learn more.

Stumbling across an enlightening article from the Independent revealed the shocking truth: trains really do have single-use sand dispensers that provide emergency braking assistance when there's reduced traction between the wheels and the rail. These slippery rail conditions can be caused by moist fallen leaf debris on the track - the infamous "leaves on the line" - and it's become a more common problem now because today's trains use disc brakes. These are generally superior to the previous block brakes - but unlike block brakes, they aren't as effective in "removing leaf mould and other debris".

It was a bit of an eye-opener. I'd found the idea that fallen leaves could be a hazard for several hundred tonnes of passenger train a bit laughable, and the phrases "leaves on the line" and "the wrong kind of snow" just sounded like nonsense excuses for poor service. It's odd but salutary to find out after all these years that it was a real issue after all, although it's also indicative of how poor train operators are at explaining these problems - or maybe of how little the travelling public expect to be told the truth.

So aside from the specifics, I'm sure that buried somewhere (maybe under more fallen leaves?) there's also a wider lesson about trust and communication, which could perhaps be applied to other situations where technical problems have to be explained to a lay audience. It might be worth thinking about next time you're (say) stranded at Stafford station due to leaves on the line.

* Cows on the line to you and me.