A simple matter of…

Whilst waiting for a tube train, I wondered why instead of one very long train every 5-10mins they don’t run short trains more frequently. Historically, longer trains would be more efficient – fewer drivers required and because you need to leave gaps between trains, the throughput is higher.

Of course these days we have automated trains so using this approach:
* shorter wait for trains
* less crowding on the platform (probably)
* it’s automated so no chaos caused by strikes
* shorter platforms – less distance to walk, cheaper stations
* more flexible trains – they could go to a wider selection of destinations (and more directly)
* with shorter trains if one breaks down you could possibly get another train to shunt it gently into a layby

There are a few disadvantages:
* automatic systems are often complex and require more rigorous safety measures than manned systems
* train efficiency may well be lower
* passenger safety (from other passengers)

I’m sure it’s already been thought of many times before, so why hasn’t it been done? The advantages seem huge compared to current systems.