Requirements for Pit Type Scales

PURPOSE: This rule covers installation requirements for pit type scales. (1) The minimum pit depth, measured from the bottom of the weighbridge main beams to the floor of the pit, shall be twenty-four inches (24") for load cell or two (2) section levertype vehicle and axle-load scales, thirty-two inches (32") for three (3) or more section lever-type vehicle scales, and fortyeight inches (48") for scales used for weighing livestock. (2) The pit floor shall be of concrete sloped to a drain or sump, or both, located in close proximity to the entrance of the pit. (3) One (1) opening shall be provided in the scale platform, pit neck covering or pit wall to provide access to the pit, except that two (2) openings shall be provided in the platform for scales with platforms longer than forty feet (40') for axle-load and vehicle scales. (4) Openings in the scale platform or pit neck cover shall be either a circle of not less than twenty-four inches (24") in diameter or a square with at least twenty-two inch (22") sides. (5) An entrance through a pit wall shall be a minimum of three feet (3') wide. The top of the opening shall not be lower than the bottom of the main girders and the bottom of the opening shall be approximately even with the floor. The center line of any lever extending through a pit wall opening shall be at least twenty-seven inches (27") from one (1) side of the opening. (6) Main load bearing piers shall be of concrete poured to a depth lower than the local frost line. They shall be of monolithic construction with the walls or tied to the walls or floor with reinforcing steel. Steel perimeter coping shall be installed around the inside edge of the top of the pit walls. Adequate provisions shall be included in the pit wall to prevent damage by platform restraint devices. (7) Approaches to Pit Type Scales. (A) Vehicle Scales. On the entrance and exit ends of a vehicles scale there shall be a straight approach a) the width at least the width of the platform, b) the length at least one-half (1/2) the length of the platform, but not required to be more than forty feet (40') and c) not less than ten feet (10') of any approach adjacent to the platform shall be constructed of concrete or similar durable material to insure that this portion remains smooth and level and in the same plane as the platform. However, grating of sufficient strength to withstand all loads equal to the concentrated load capacity of the scale may be installed in this portion. Any slope in the remaining portion of the approach shall ensure ease of vehicle access, ease for testing purposes, and drainage away from the scale. (B) Axle-Load Scales. At each end of an axle-load scale there shall be a straight paved approach in the same plane as the platform. The approaches shall be the same width as the platform and of sufficient length to insure the level positioning of vehicles during weight determinations. (C) Livestock Scales. Approaches shall be of reinforced concrete. On at least one (1) entrance there shall be a ten-foot (10') approach at least as wide as the gate with a minimum gate width of four and one-half feet (4 1/2'), accessible for movement of test weights to the scale platform. This approach may be on an incline from the scale platform, but not such that would hamper the movement of test weights onto the scale platform. 1. Livestock scales installed prior to July 1, 1998, shall be exempt from the requirements of subsection (7)(C) of this rule. (D) Railroad Track Scales. Approach rails must be installed in accordance with the requirements as outlined in the AAR Scale Handbook. (8) All scale pit walls having traffic adjacent shall be reinforced to withstand traffic pressures. (9) All scale pits shall have 110-volt alternating current (AC) outlets and permanent lights. (10) Mechanical indicators shall be mounted on steel or concrete and made integral with the scale pit. (11) If any provision of these rules is declared invalid, the validity of the remainder of these rules shall not be affected. AUTHORITY: section 413.065, RSMo Supp. 1997.* Original rule filed Dec. 30, 1975, effective Jan. 9, 1976. Amended: Filed Nov. 14, 1977, effective April 13, 1978. Amended: Filed April 22, 1981, effective Sept. 11, 1981. Amended: Filed Nov. 3, 1997, effective May 30, 1998. *Original authority: 413.065, RSMo 1983, amended 1993, 1994, 1995.