wtfcaniuse says... They would have had exact clearance measurements in the planning phase, they didn't just start work and make up the height as they went along. jmd said: Those signs are the result of a different crew and I'm sure they only wait till after it is done building to do the final measurments, and then they need to submit paper work to get the sign requested and made which could take a while. I would be interested in knowing what the hell they were doing on the second weekend. They did an awful lot of passes and tarping, and you can also see what looks like dirt, but in the end the cement bridge is still whats exposed.