America is a collection of thousands of jurisdictions that all have authority based on who is paying for the road. Interstates are controlled by the Federal Hi

America is a collection of thousands of jurisdictions that all have authority based on who is paying for the road. Interstates are controlled by the Federal Highway Commission and must meet Federal Highway standards as the federal government generally pays for them State Routes are controlled by State Regulations County Routes are controlled by County Regulations City Routes are controlled by City Regulations There is zero standard that is applied universally. This is is viewed by some as a negative personally I prefer the federalist system over a central authority Most State and Federal routes do have Minimum Heights, though exceptions can be made, one thing we often see in the US not remeasuring the surface, there have been more than a few time where the height is reported as X but that measurement was decades old and several resurfacing layers had been added to the real height is lower. Or the road pitches to one side and someone measured the highest side not the low side