I needed to get into Missoula, MT last week, and woke up the middle of the night before thinking about the RR overpass going into town. I didn't remember the clearance height (which is 13'-0") until I turned onto Orange Street and saw the signs. My published height is 12'-3", but I have actually measured 12'-9" to the top of my antennas. I have two sacrificial (magnetic) antennas at the front of the cab that alert me to low branches, etc. While driving very slowly under the overpass, I heard nothing, so all was good. I slept better the next might.