Everything2.com defines the Law of Gross Tonnage as follows: ”. . . an accepted nautical convention that when a sea-going vessel has the right-of-way as established by the International Regulations for Preventing Collisions at Sea, 1972 (72 COLREGS), it should nonetheless give way when faced with a larger vessel. This law is regularly invoked in non-maritime situations, such as when a bicyclist with the right-of-way invokes the Law of Gross Tonnage to avoid the Sport Utility Vehicle (SUV) that is about to cut them off.
 
“The heavier vessel always has the right-of-way. There is no explicit directive in maritime regulations or law for the Law of Gross Tonnage other than it is common sense that giving way and being alive is usually better than forcing one’s right-of-way and being dead.”

This law appears to apply universally in situations where two moving objects may attempt to occupy the same space at the same time. This can be especially problematic when a runner and a car are involved. Be both vigilant and forgiving!

Trivia Note: While the Urban Dictionary lists several definitions for a sh**load, a club member with cargo expertise has established its value at 120 metric tons or the capacity of a 747-400, which is a lot of gross tonnage. So within the club, this appears to be the working answer.