In ,
Paul Corfield typed:

.... your proposal reverses the direction of the *single track* loop
line
between T123 and T4. You are assuming that the train reverses at T4
and
goes back to T123. This would mean bi-directional working on a single
track line which would severely reduce the headway to T4.


It would *increase* the headway - trains would not be able to
follow each other so closely.




Bob