Help with animation

I'd like to ask for some help with an animation. There is this bridge in the picture and on the bridge there is a train.

I'd like this train to slowly move towards the right, but only when it is within viewing distance from the driver's train. Once it has moved towards the right and the driver's train has passed it (or it gets out of viewing distance) it should disappear, so that if the driver returns to this point the train shouldn't be there again. Can anyone help me with this?

It seems your problem is partly the same as the road traffic over bridges which I use in the Irish routes (which is based on NWM code, they did it first). And partly the same as the approach control I use for crossing gates and and their "distant" signals. Not sure how to write the combined formula though.

A "Animated Cookbook" would be very useful. All I've had to work with was the original OpenBVE "Demo Route" with examples of code.

Yes, step by step tutorials would be useful.

I have done the same within my route, the only difference is the moving object on the bridge was a lorry. See this:

Code:

[object]
Position = 0, 0, 0
states = Axor.csv
RotateYFunction = 1.571
TranslateXFunction= if[trackdistance[0]<450 & trackdistance[0]> -300, -(0.75)*trackdistance, 0]

Any questions - let me know.
Hope this helps.

Thanks a lot, I'll give it a try as soon as I find time to get to it.