Yes it was tricky and took some time :moo: But I still like the idea because the defending team is able to bias the way the tank goes by building only one barrier (blocking one way the tank could move). When both barriers are built, the offensive team is able to decide which way the tank should go by either blowing up the left or right barrier.
I’ve made a box map and copied the necessary things into it with some additions like forward spawns and one objective. The script is a modified goldrush script. I was too lazy to rearrange the spline points for this box map so the tank needs some time until it shoots a hole in a wall at the end of it’s journey. With ETPro one could increase b_moverscale 
You can get the map and script file here.
Shaderman