Divers in cold water | bridge work | Kirby Morgan Dive Helmet

Divers place rocks (riprap) around bridge pillar to protect from scour (affouillement) It remains the most common countermeasure used to prevent scour at bridge abutments. Riprap, also known as rip rap, rip-rap, shot rock, rock armour or rubble, is rock or other material used to armor shorelines, streambeds, bridge abutments, pilings and other shoreline structures against scour, water or ice erosion.

It is made from a variety of rock types, commonly granite or limestone, and occasionally concrete rubble from building and paving demolition. It can be used on any waterway or water containment where there is potential for water erosion.

Bridge scour is the removal of sediment such as sand and rocks from around bridge abutments or piers. Scour, caused by swiftly moving water, can scoop out scour holes, compromising the integrity of a structure.