Quote:
Originally Posted by RandyNH
I70 in Colorado has 7% grades, just curious as to where your limit information came from?
|
Info comes from "Interstate Highway Standards"
6% is generally allowed in mountainous areas and hilly urban areas with up to 7% grade on mountainous roads with speed limits below 60 MPH.
Since interstate roads where started to support the movement of our Armed Forces they tried to make it easy for military trucks of the day. Trucks of the 1950/early 60 did not have the horse power we have now.There where still flat head 6 cylinder engines in many truck when the Interstate planing was going on. They could not go 60 down hill let alone up hill. Look at the truck we used in Korean War.