Do You Know the Height of Your TC?
Knowing the height of your TC can prevent a very costly disaster. Understand that every state is different about whether they mark the height of bridges, tunnels or not, or whether that signposted is accurate.
Upon approaching a state/town bridge or tunnel, don’t always trust the post height sign. Local and state bridges don’t have to abide by federal regulations. Some bridges or tunnels may be significantly lower, particularly when you get away from major commercial areas.
MEASURING YOUR TC
Start by placing your TC on a hard level surface such as a driveway. Measure from the ground to the top of the highest object on your TC. Considering that the air conditioner and/or TV antenna/satellite dish could be the highest objects.
Once you have the height, consider adding a safety margin – add two or three inches to the height and post this new height on your dashboard where you and your passenger will see it. The extra safety margin of those extra added inches is when the road’s original surface has been paved over. Repaving can lower bridge and tunnel clearances by 2 inches each time it is repaved. After the last repaving job, the local highway department may not have updated the low clearance signs.
Another safety measure to consider when using a GPS unit is to overstate the height of your TC in the GPS height settings. By adding two inches from the recorded height and then inputting the higher height.
For example – If the height of your TC is 11 feet, 6 inches, set the height in the GPS to 11 feet, 8 inches in the GPS unit.
When you input your itinerary into the GPS, the unit should warn that a bridge or tunnel with low clearance is on your route. This will allow you to alter your route. If you must take a particular road, consider confirming the height of the low clearance with the local authority. The local police department and/or Department of Public Works (DPW) may be able to advise you.
WORDS OF WISDOM FROM THE US DEPARTMENT OF TRANSPORTATION, FEDERAL HIGHWAY ADMINISTRATION:
Chapter 2C, Warning Signs and Object Marker, Section 2C.02, Application of Warning Signs:
The use of warning signs should be kept to a minimum as the unnecessary use of warning signs tends to breed disrespect for all signs.