I think railbuses and hi-rail buses would be great vehicles because they buses that are on rails and hi-rail buses have rubber tires so they can stop in a instant. Railbuses mostly had steel wheels but they can stop more quickly because they not pulling a long string of cars. Missouri Pacific (MoPac) had Twin Coach rail-buses that operated in Texas to replace electric streetcars in 1948. German Federal Railways also had railbuses that were used for commuter service. A pair of two foot gauge railbuses in Maine sometime in the 1930s.
The Class 121 is strictly a DMU. One of the few interchangeable "road railers" in the UK was the Karrier, procured by the LMS for service on the SMJ from Blisworth to Stratford, where it switched to road mode for the run to a hotel. LMS Karrier Ro-Railer - Wikipedia
It was built exactly the same as many other classes of 1st generation dmu, mainly to a BR Derby design only as a single car with 2 cabs. It could also be coupled in multiple with the aforementioned classes for service flexibility.
This was also considered a "railbus" albeit without road capability... AC Cars Railbus (railcar.co.uk) and this: Waggon- und Maschinenbau GmbH Donauwörth railbus - Wikipedia
While a route for them in TSW2 may be a bit iffy, there was the Galloping Geese of the Rio Grande Southern, not to mention all but 1 have been preserved, with a replica of #1 being built in 2000.
Why not add an East German railbus the DR Baureihe 171 172 railtour Riesa-Dresden Dresden chemnitz Rapid Transit While RRO RSN Main Spessart Bahn Köln Aachen München Augsburg Hamburg Lübeck Get it's West German equivalent the DB Baureihe 795 Location is Bochum Dalhausen museum where this runs past the big Rbf Hagen Vorhalle
I think a route set on the Rio Grande Southern would be a great route set during the steam era and during the 1930s they're were built because the railroad couldn't afford to operate any steam locomotives so the built these galloping goose out of Pierce Arrows and old Buicks.
