How about something counter-intuitive: lower the limit? There is a built-in hard limit imposed by the structure itself. Set the marked limit to something well short of that, like 8 feet. Then add very obvious soft barriers like light swinging bars to indicate the lower boundary. That would encourage anyone driving anything that might actually hit the hard limit to take an alternate route. (Of course, that means there…
" it’s not practical here. There are many overheight trucks that have to be able to drive right up to the bridge and turn onto Peabody St. in order to deliver supplies to several restaurants. Making Peabody St inaccessible from Gregson St would make the restaurant owners and the delivery drivers very unhappy." [1] at the end of the it seems most of the trucks are often Rental Trucks drive by people that likely should…
Then again, maybe a large portion of the crashes are from people who forget they're driving a truck, so that might just make the carnage worse...