As mentioned earlier, the height may vary due to resurfacing of the road. However, that measurement is the smallest clearance under the bridge, which most often times, is at the outer edges of the road. Just be sure you are on the road and not cruising down the shoulder and you should be fine...
Also, the published height should be inclusive of any appendages sticking up or out (if talking width). That can change though if you went to a larger tire, flipped the axles, tow nose up, etc....
TV: 2015 F-350 DRW, CC, 4x4, with 14k GVWR package, 98 gallon TransferFlow Aux Tank, Timbren Shocks
TH: 2014 Voltage 3950, Sailun S637 all around