I've sometimes discussed the optimal use of main-line railways with American friends, and put across the concept of trains with different stopping patterns sharing the same tracks.

The one which used to work nicely was on the Midland Main Line, running north from London St. Pancras. The pattern was that a semi-fast train would leave for Nottingham (180 km) and call at principal stations to Leicester (160 km). At Leicester, it would wait a few minutes for the following train (going to Sheffield, 270 km from London, via Derby, 200 km from London). This ran non-stop from St. Pancras to Leicester and then stopped at the adjacent platform to the Nottingham train.

Passengers from intermediate stations going to Sheffield could make a simple cross-platform interchange at Leicester. Passengers wanting a fast service from London to Nottingham could catch the non-stop train to Leicester then cross the platform to the train which had left London before theirs. The service was pretty optimal for all concerned.

A similar concept is used today by Eurostar. Their big constraint is the Channel Tunnel: their optimal speed is higher than that of Eurotunnel's shuttles so it's best to run the Eurostar trains close together - a technique known as flighting.

At 10:57, a Brussels train leaves St. Pancras. Just over 15 minutes later it stops at Ebbsfleet for passengers from south-east London. While it's standing in the station it is overtaken by the 11:00 non-stop train from St. Pancras to Paris. The two trains then travel some 3 minutes apart through Kent and the Channel Tunnel to Lille, where the Brussels and Paris routes separate.

A very nice use of scarce infrastructure!

Yesterday I left the College of Europe, in central Bruges, at 15:50. I got to my house 30 km north of London at 20:00 - just over 5 hours later, allowing for the change of time zone between Belgium and the UK.

What time would I have got there if I'd flown instead of using Eurostar?

I was in Brussels Midi at 17:25, so I could have been at the airport by 18:00: I could then have caught the 19:15 flight arriving Heathrow at 19:30. I would probably have made the 19:55 Heathrow Express and been in Paddington at 20:10. I could have been at St. Pancras by 20:40 and been indoors by 21:20 - 80 minutes later than I actually arrived.

Moreover, using the train I had 2 hours of very valuable working time - I would not have been nearly as productive on the flight, partly because the journey is so split into segments and partly because of lack of space.

A real live example of the time saving possible using a high speed train rather than a plane for a journey which was not city centre to city centre. I'll watch out for others!