Silver Eagle nailed it. No expansion joints, but one has to go appropriately slow for the road to Alaska. I always counted on 50 mph average if driving a single vehicle (passenger vehicle or light truck); 40 mph if driving a single big rig (2-1/2 ton, etc); and no better than 35 mph average if towing on a personal mission (whether small rig towing a trailer or bigger rig / bigger trailer). Work travel (the infrequent 18-wheeler and load) could be pushed a little bit harder because the equipment was stouter.
In any case, make time on the I-XX and US-XX roads in the L48; take time to enjoy the scenery on the AlCan / Alaska Highway.
