It's an effort to stop people on motorcycles, we had a problem with them going down our footpaths where I live, so the council had a gate-like thing with 3 bars that you had to navigate around, which was difficult on pushbikes probably impossible on a motorbike. That would have been a better solution I think, then there's more width for wheelchairs etc but it still doesn't allow longer things like motorbikes in. Overall I can see why the park did it, and the thought of a ham not being able to get through 20 inches sideways is hilarious.