Ok I know that the opponents don't
do boats but if they do, thats what you have to do to block them. You block
the two ends of their depot with two of your depot.
Now if you want to cut your expenses in half when you put some rails in a farm location, plant a tree before!
You see that it only cost you 105L
while it could have been 454L!
Also here's a little trick you can
play to the other players vehicles.
Build a cheap train and make it go on the opponents route. Just stop the train before it cross the road. When the truck(or bus) come to the rail just let your train go! You will crash the opponents truck. They will have running costs for the time the truck is still crashed on the screen.