sawing bars of a gate?

[nkmol]

first i made a broken sewer gate and putted some resized copper tube instead of the original sewer bars (that are broken). but that doesnt looks that good, because i just pick the "tubes" up so i where wondering if there was a way to let a saw saw trough the sewer bars?

or maybe i could change the broken sewer into sewer gate worn, whith the active box?

the hardest part is just the scripting. could somebody help me take the first steps? please explain stap by stap, if it isnt much to ask
thanks