Why do you need three trains? Surely the trains would just run A-B-C-B-A on both sides?
There would be a huge frequency drop with an extra station and only 2 trains. They are pretty full as they are. There are 3 trains not 2 anyhow. The third one came in July and is stored under t5c.
Also if you are on the trains you are "sterile
Only if you are departing. Arriving passengers arent deemed sterile so cant mix.