Fortunately all the barriers where I work are either vertical lift, operated by a security bloke in the entrance room, or are a pair of gates that swing open and are padlocked when not in use. Considering the number of vehicle movements every day, they’re the only real option.
I wrote off a ‘53 split-screen Minor hitting a barrier that had been left closed over a weekend when normally it was open all the time, I swung into the entrance as I always did, hit this large steel tube with a square end plate hard with the driver’s side screen pillar, the tube shot back, hit the wall and bounced back, the steel plate catching the rear bodywork under the window, the corner slicing through the steel. The police had been checking a small motor servicing business over the weekend, and had kindly closed the bar, when it had always been left open and swung back against the wall, I hadn’t even noticed the damn thing was there!
No comeback and insurance wouldn’t cover it. Bugger.