[Symbiote]

There are electric (battery) versions of these vehicles for use in tunnels, where diesel fumes would be a problem. Much construction equipment is often converted roadbuilding equipment, and that's still diesel powered.

However, railway vehicles tend to last for decades, so it might take a long time for everything to be electric. The people buying them can both afford and have the expertise to purchase reliable, repairable equipment. It's then run on a perfectly smooth "road" without much rough handling.