Reuploaded and updated version of Train Pause by dorfl : https://mods.factorio.com/mod/trainpause
All credit goes to him, the original author.

Intended behaviour

If an entity connected via circuit to the combinator is a train stop with a parked
train, peek at the the train's schedule and emit a green signal if the next station
is available.

"Available" means: one or more stations with the next name are enabled and do
not have a train already en-route or stopped.

This has only been tested with relatively simple train setups so far so bug reports
welcome...
Setup

At any station where trains should wait:

Connect the combinator to the train stop with a circuit wire
Set trains to wait at the station until circuit condition GREEN > 0
Set train backlog (number of trains to release per destination station name) in mod settings

Use Cases

Works OK: Controlling train throughput for a single destination station using one or more pause stations (the train buffer idea, but without the requirement for buffer proximity)
Works OK: Controlling train throughput for multiple destination stations with the same name roughly equidistant from the pause station(s), such as between city blocks.
Doesn't really work yet: when the multiple destination stations with the same name are very spread out, such as resource patches, because the Factorio train pathing can still be problematic. In that case have found it's still necessary to disable stations while in use (+ 1 second after departure).