Concrete construction, road/street construction: Worker uses grooving tool to cut control joint into fresh concrete. The control joint introduces a plane of weakness through the curb, so that if the curb concrete should crack, the crack will form at the control joint, rather than at random. The worker will next use his trowel to smooth out the rough line left by the outside edge of the tool. Notice other control joints already created. Huron Parkway at Huron High School, just North of Geddes, Ann Arbor, Michigan 2005.

Concrete construction, road/street construction: Worker uses grooving tool to cut control joint into fresh concrete. The control joint introduces a plane of weakness through the curb, so that if the curb concrete should crack, the crack will form at the control joint, rather than at random. The worker will next use his trowel to smooth out the rough line left by the outside edge of the tool. Notice other control joints already created. Huron Parkway at Huron High School, just North of Geddes, Ann Arbor, Michigan 2005.