I wasn't sure what forum to put this in, but I thought maybe some civil engineers might have an answer. What is the average annual cost per lane-mile for highway maintenance? Ballpark answer/order of magnitude is all I'm looking for. I know there are a lot of variables, so assume typical US interstates, 30-40 years old, four season weather, moderate level of truck traffic. Just doing some back of the envelope calculations for personal interest, but I thought this must be something civil engineers estimate when they build a road. Thanks in advance.