Well Yes....... and no. The Route is a 24 hour working timetable. So even if you just walkabout the trains will run via "Despatcher" (the systems AI) by itself. So some locos you come across in yards , sidings or stations will wait until you start that journey when the correct time for it to be started the time they are supposed to start, but you can sit in them and do the journey but if it says the current time is 1415 and the service starts at 1430 then you have to wait (after you have sat in the drivers chair) until 1430 to be able to drive. I have done alot of Walking the route videos on my You Tube Channel where I literally walk from one end of the route to the other (over several episodes). Regards Hentis
I have found some locos you can and others will not let you. it is just a matter of trying. Though I have only tried shunting locos about "On Shed" or in a Yard.