A critical consideration in developing equipment specifications for an access control system is the anticipated traffic through all control points. If a preliminary examination of anticipated traffic flow indicates 100 or more entry and exit transactions per day, it would be cost-effective to specify all heavy-duty equipment. The mechanical locking device usually provides for an uninhibited exit. In systems where the control equipment does not provide for release of the locking device, the functional capacity of the system can be enhanced by the use of a motion detector to provide automatic unlocking of the door when a person approaches from the protected side. In selecting a proper qualifying device that will allow authorized personnel to effect their own entry and exit by some possession or physical characteristic, it is necessary to determine the level of control desired, taking into consideration the number of persons using the system and the various levels of access required for each person. An access system should eliminate as many human factors as possible in determining the operating model of the equipment. A chronic problem in access control is the entrance of persons immediately behind those with authorized access. This can be prevented by the use of a full-height turnstile that permits only one entry at a time. An antipassback feature may also be used to require authorization for exit as well as entry. The transaction recording capabilities of on-line systems will provide records indicating if a card was used properly and at what time and place it was used. Cards rendered invalid by improper use will not activate the door release system.