Are there any messages from the drivers? Check the message window for anything like "Can't plot route", "Junction missing lever", etc.
If there are any broken tracks, such as those connected to a railroad crossing, station or other interative industry for example, the train will not move under AI control. They'll ignore any commands you give them to move the train.
To find a broken track, you need to either drive the entire route yourself, and wait to derail at the broken track, or inspect the route from above.
Make sure your track spline tool has the option (under Surveyor options) to show spline points. All of the properly conneted spline points should be yellow. If there are any white ones on the track, this can mean there's a problem. These can be fixed simply by clicking on them. If the circle doesn't turn yellow, this means that the track is still broken. Sometimes the tracks are butted real close, or over lap instead of connecting. You need to use the track spline move/placement tool and move the spline track end on to the end of the fixed-track object like a crossing or industry to connect them, or in the case of a broken spline, make sure that the circle has turned yellow.
To find a missing junction or track mark, you need to walk the route slowly and inspect the whole thing mile by mile, inch by inch. Make sure the yellow track marks are facing the proper direction, and that there are no missing levers. If there's a missing lever on the intended route, and you drive the train, the train will derail. Finding an incorrect trackmark still requires the walkabout in Surveyor. The reason being that humans don't see the direction markers in Driver, just the AI drivers do.
John
