gravelling
n.— «Soweto youths aren’t alone in their crazy train-surfing habits.…Typically spurred on by whistles and admiring female looks, young train surfers will variously run against the walls of bridge underpasses (“The Matrix”), drag their feet on the ground (“gravelling”), or run noisily along platforms (“spara-spara”).» —“The Big Picture: Train Surfing” by Sean O’Toole Times (Johannesburg, South Africa) Oct. 28, 2007. (source: Double-Tongued Dictionary)