As a former commuter from the Valley I can say from experience that there are no rules on the Glenn. Cops, especially APD, routinely do 10 mph over the speed limit. 75-80 is pretty much the accepted normal commuting speed and it's absolutely nothing out of the ordinary to be passed by those doing 80 and up. Between Eagle River and Anchorage it's gets worse, thus the "Glenn Highway 500" nickname. You see plenty of APD cars traveling in both directions but rarely do you see anyone pulled over. The only way this will ever get any better is for the Muni to appropriate the funds to hire additional officers to do nothing but write tickets on the Glenn from Airport Heights to the Old Glenn overpass. Not just for a few days or a week but permanently.  From what I am reading here, the Seward Highway is no better, probably worse as it is two lane and far from straight. Funding for patrolling both corridors should be a priority, as a matter of safety.