For important train commuters lines I believe something has to be done. A failure should not affect the peoples whole day. Trying to find a bus, taxi or getting stuck at the Central Station.
My idea is to build an additional independent train commuter line. Such that if one line gets an error people can board the other line.
Its not enough to build additional track for higher traffic volume. The tracks are dependent on the same failures and this is not what we want.
So for example. A two independent line system should have independent power supplies and maybe a big and a little Central Station.
With this idea. People get a much needed backup and for a carbon emission free future public transport must have an excellent uptime.