[vmarsy]

In Seattle, underground tunnels were shared by trains and buses until March 2019[1], here's an video showing it in action, a bit older, (possibly before there were any trains?): https://m.youtube.com/watch?v=etT_wVuKy_I

Why not use buses in those tunnels as well? Maybe there is no traffic jams above ground?

[1] https://en.m.wikipedia.org/wiki/Downtown_Seattle_Transit_Tun...

[donavanm]

The seattle shared use was always temporary iirc. The buses were a reliability problem for the trains, impacting on time performance. But what led to the exclusive use was going to shorter inter train timing where there’s simply not enough time to wait for buses to clear the train platforms between arrivals.

[vmarsy]

Right, but like every project, "temporary" can go a long way :) from wikipedia:

> The DSTT was used only by buses from its opening in 1990 until 2005, and shared by buses and light rail from 2009 until 2019

That's 15 years with bus only, then 10 years of shared bus/train.