On some Routes you could utilize a Rail Motor Cars to get around. The reference bellow has some plausible options, these options cover only the American routes but it's a start. Squeezing in a Rail Motor Cart in Freeroam among the usual traffic could be a challenge so you don't get in their way too much. You might have to create some facilities or rain parkings speficially for it so it can have it's own parking spots. https://classic.txtransportationmuseum.org/collection-rail-motor-cars.php
