Does anyone happen to know the laws and/or customs about posting overhead clearance signs? What's the minimum clearance you can expect on an overpass if it isn't posted? I also worry about lightposts, etc that hang out over streets and pruned tree branches.
Got this from a MN FAQ page. Doesn't help with tree branches, those you have to look out for yourself.
Question: What is the legal height for vehicles on highways and when does Mn/DOT install clearance signs?Answer: The legal height for vehicles is 13 feet, 6 inches. The low clearance sign is used to warn road users of clearances less than 12 inches above this legal height. Clearance below bridges on freeways is typically 16 feet, 4 inches and overhead mounted signs is 17 feet, 4 inches.
Jon & Chris Everton
1986 40' Dog House #86
0 hp 8V92 Allison HT740
Soon to be 500hp ISM with ZF 6 Speed
I don't know of any standards other than the Interstate highways, which require a minimum of 13'6", I believe. We use the trucker's atlas and it not only shows all the roads on the national truck network, but lists any low clearances by state in table form. If nothing is listed, you can assume 13'6", generally.
Light posts have never been a problem, but tree branches can be, especially on side streets. On major streets, you can usually tell if the trucks have been traveling on them as the trees will look squared off