Pretty simple really. If offered a long load.. just do the math at 47mph and see if there is enough time for the load and a break. Ask to speak to safety and they generally will tell you if you have enough time. Sometimes safety will figure the load at '5 under' meaning 5mph under the speed limit in the states that you are going through. This is a bit more accurate for calculating average speed for a van. Seems to work for me 98% of the time. They really don't want to swap anyway.. costs time and money.