100 air miles can be any length of road miles. no where will you find that it has an equivalency. it all depends on the road.
when i was working local construction. we did a job that traveled 75 miles from the yard to the job. plus 150 miles to dump the dirt. that 225 miles. but from the dumpsite back to the yard was 175 miles. taking a different route back. the air mile radius was 90 miles.