Rail 101 - Size does matter - Length

This article is part of a series I'm starting to explore some of the basics of rail. They'll be slightly technical articles, but hopefully you don't need to be a rail expert to understand them.

If you look back over time you can see an interesting yet stark trend in the length of rail.

In the early years of iron rail, manufacture of rails just 2 metres in length was possible although this quickly progressed and now routinely 120m rail (60 times longer!) are manufactured and delivered in Europe.

Why have rail lengths increased so massively? The primary reason is quite simple - Joining rails reliably is difficult. I know many of my welding or joining colleagues will disagree but if you take a look at the statistics then you find some clear evidence that says otherwise.

This data is an amalgamation from several well respected customers, so it isn't just one rogue network that is skewing the data. Indeed if I looked back 5 years you'd see an even bigger block of failures relating to the rail ends.

Over 1/3rd of broken rails break at the ends, whether that is welds or joints. (and jointed track in these networks is not very common). Although ends count for a small proportion of the track length, they account for the largest proportion of failures (and also a lot of cost).

So for a reliable railway you need to do two things.

1. Minimise the amount of joins in the rail
2. Make those joins as good as they can be

If you take a look at the number of joints needed to make a single kilometre of track, you’ll see just what a huge effect on the number of joints needed the rail length has.

It is clear why rail lengths have increased over time due to the desire to have lower failures and also reduced maintenance of the railway. Moving from 18m rail to 108m rail reduces the number of joins by over 80%! The challenge is of course manufacturing and indeed handling these rail lengths, but that is an article for another day.

I hope you’ve enjoyed this little look into rail. Please feel free to follow me, browse my other rail related posts on LinkedIn and of course follow my twitter account for more rail related information.