If you've ever taken public transport in Paris, you may have noticed a surprising fact: the metro and the RER don't run in the same direction! You'd have to be pretty bored to think that, but it's a very interesting explanation, coming as it does from the great history of railroads across Europe.
If you didn't know, RER trains always enter the station from the right-hand side of the platform, while metro trains enter from the left. Why such a difference on similar lines? Quite simply because the way trains run comes from England, which was the first country to offer railroads on its territory. Since the English drive their cars in the left-hand lane, trains have followed suit.
When they arrived in France in the 1830s, this direction of travel was retained, enabling railwaymen to perform their shunts with their heads outside the locomotive without the risk of being hit by another train. RERs, unlike metros, are operated by the SNCF, and run like trains, on the left-hand track, which means they arrive on the right-hand side of the platform.
As for the metro, born in 1900 in Paris, the City of Paris wanted to break away from the traditional railway system and show a little modernity. So much so, in fact, that they created a small gauge rolling stock, running on the right-hand side, simply so that the railway companies could never mix their tracks with the Paris metro! Didier Janssoone, a railway operations engineer, points out in his book that a metro can run on rail tracks, because thetrack gauge is exactly the same. You'll want to think about that the next time you take public transport!
Metro and RER updates: closures, work, and demonstrations in Paris this Friday December 19, 2025
In a flash, get all the latest updates on traffic and transportation in Paris, refreshed in real time. Whether it's the Metro, RER, or Transilien services operated by RATP, construction work, ongoing circulation, major events, or demonstrations — we provide all the essential information you need before heading out in Paris this Friday December 19, 2025. [Read more]
Metro and RER updates: closures, work, and demonstrations in Paris this Friday December 19, 2025
