Empty Pipes

This map shows how long one would expect to travel to any point in Europe starting in London, using only trains and walking at a brisk rate of 5 min / kilometer.

Other Cities

Amsterdam Antwerp Barcelona Belgrade
Berlin Birmingham Bratislava Brussels
Bucharest Budapest Copenhagen Dublin
Frankfurt Geneva Helsinki Jena
Ljubljana London Madrid Minsk
Oslo Paris Podgorica Prague
Riga Rome Sofia Stockholm
Tallinn Vienna Vilnius Warsaw
Zagreb Zurich

The origin of this map is described in slightly more detail in the original blog post.
Errata / Disclaimer
Everything is an estimate. Rounding errors abound. Don't use this for anything but entertainment and curiosity. But you already know that.

Travel times to areas close to the coasts are prone to large errors. This is because travel times are calculated and interpolated on a grid. Points in the water are heavily penalized so if a city lies between points sampled on land and water, the interpolated time may be extraordinarily large. Thanks to @ChristianTanner for pointing this out for the very stark example of Dublin, where it appears that it takes 14 hours to travel from Dublin to Dublin.

Some data may be missing. There may be faster connections. If you find issues, please let me know and I'll do my best to fix them. Thanks to cuicuit on reddit and @yorksranter for pointing out missing data for Paris and London!

Ireland and parts of Spain are not well represented due to missing data.