Applies to all operations involving shaft sinking for bridge footings, piers or foundations. Includes concrete work, pile driving, excavation or lining in connection with the operations. Also applies to specialist contractors engaged in pneumatic caisson work for bridge or pier foundations. Contemplates specialist contractors engaged in all operations involving non pneumatic caisson work for bridge, abutment, pier and underwater foundation construction up to the completion of the subbase or sub foundation and specialist contractors engaged in all operations involved in non pneumatic cofferdam work.