Abstract: Vehicles are screened by weight for the presence of concealed explosive material, weapons, contraband and/or personnel by retrieving weight values for vehicles and categories of occupants and contents based on operator input and subtracting those values, as selections are made by an operator, from a measured vehicle weight. Excess weight is then compared to a specified tolerance, and the vehicle may be cleared or other appropriate action taken, including automatic control of movable barriers. The estimate of a weight value for various categories of vehicle occupants is adaptively altered to improve screening accuracy.