The Pacerailer was a prototype railbus built by Charles Sadler Ashby 's Sadler Rail Coach Company ( SRC ) in the 1960s .
A prototype railbus is a vehicle consisting of a bus - style body on a four - wheeled railway - vehicle chassis .
The Pacerailer was a prototype railbus , a vehicle consisting of a bus - style body on a four - wheeled railway - vehicle chassis , built by Charles Sadler Ashby 's Sadler Rail Coach Company ( SRC ) in the 1960s .