The Federal Highway Administration, which is part of the U.S. Department of Transportation, lists ranges for the heights of bridges on rural and urban roadways, including freeways, arterial roads, collector roads and local roads. Low clearance bridges also have warning signs located on them.
The FHA maintains minimum bridge heights for the purposes of national security. Freeways must have 14 to 16 feet of clearance, while arterial roadways must have 14 feet. Collector and local roadways must also have clearances of 14 feet. If driving a large truck, drivers must be wary of driving through the Northeastern United States or Chicago, because most of the bridges were built before large modern trucks became a mainstay of U.S. transportation and shipping, and they may not meet this criteria.