A revolving door design restricts building access to legitimate users
while restricting 'tailgaters' from entering a building
By Don Haerer, AHCGiven increased awareness of security problems such as terrorism, espionage and theft, businesses today have become more security conscious. Previously unsupervised entrances and exits now have guards, video camera surveillance, and/or card access systems to help monitor traffic in and out of buildings. Even with these sophisticated methods of identifying authorized users, security managers still have to deal with the problem of a non-authorized user following an authorized person in or coming in as a valid user exits. Such entry methods are referred to as piggybacking and tailgating.
Ins and outs of revolving doors
Regardless of how sophisticated the verification process is, once the swinging door or sliding door receives the signal to open, control of the number of people coming in and leaving is lost. Other social norms such as holding the door open for the next person also undermine the integrity of the building. A relatively recent but proven approach to controlled access combines the established environmental and aesthetic benefits of revolving doors with a verification device that controls access into the building. The verification device can be as complicated as biometric identification or can be as simple as a push button behind a guard desk or a card reader system.
Security revolving doors control access by restricting entrance into the building. Before an individual can enter a building controlled by card reader verification system, for example, he or she must insert a valid access card into the reader. Once that occurs, the door takes control of that user's presentation and controls attempted violations.
If someone attempts to enter the building on an authorized person's request to exit, revolving doors will safely stop, warn the user a violation has occurred and clear both users. The valid user can exit once the violator has left the door. Most manufacturers of revolving door systems offer other features, including safety devices such as cushioned wall posts, slow speed and reversing.
Automation has its advantagesSecurity revolving doors offer several advantages over conventional entrances and turnstiles. One significant advantage is that revolving doors can be used in two directions simultaneously instead of allowing passage in a single direction at a time.
This "automated security" system processes a large number of users in a short period of time with a high degree of security, reliability and safety. Tailgating is eliminated while piggybacking is severely limited with this marriage of technologies. Security revolving doors do not always eliminate guards or guard posts, but rather make the existing guard force more visible and valuable by allowing guards to monitor the building or parking area instead of being high-priced hall monitors.
Security revolving doors offer several advantages over conventional entrances and turnstiles. One significant advantage is that revolving doors can be used in two directions simultaneously instead of allowing passage in a single direction at a time. The throat openings are also much larger than turnstiles to accommodate two-way traffic. Many revolving door systems are capable of processing almost 1,000 passages per hour in either direction and most verification systems are capable of a response time of less than a second. If a verification system takes longer than two seconds, delays will occur when processing high traffic. As computer speeds improve, it is the users who will often slow down the process as they search for a card, or swipe it too quickly or too slowly or upside down. Some revolving door managers state that a realistic number of passages is somewhere between 200 and 500 per hour. The variation depends on the type of card reader and the people using the system.
Signals for monitoring
Security doors also give the facility manager a number of signals that can be monitored. Most doors have the following signals available: door in use, passage verification, security violation, safety activation and power/operation failure. Today's automated security entrances usually issue a verbal warning to users when a violation or non-standard operation occurs.
Energy and cost savings
Revolving doors have always been known for their energy-saving advantages. Given that the return on guard costs is the largest savings, one also needs to consider the energy-saving advantages, added prestige and the subtle, "non-visible" security of revolving doors. Today's cost for a single manned guard post can be anywhere from $80,000 to $150,000 per station. Multiply that figure by the number of entrances and you have a very large expense.
Closer egress points for smokers
Security doors can also be used as simple automatic doors during the day and converted to secured entrances after hours with the flip of a switch or time clock. A novel use for these doors is for smokers' egress areas. With most of today's buildings being smoke-free, companies can provide closer egress points for smokers without requiring them to walk long distances or adding monitor stations.
Revolving door operation
Most revolving door systems are very simple. Once the door receives a valid signal from the verification system, the user will step on a mat or the door will begin to turn. As the door reaches the "X" or closed-in position, the door will verify that the user completed or did not complete the passage. This is another major difference between conventional entrances and security revolving doors. Sliding doors, swinging doors and turnstiles can only indicate that the entry system was moved or rotated. The revolving door, however, is the only system that sends a "handshake" signal to the verification system stating whether or not a person entered through the door.
Security revolving doors can be fitted with an electric collapsing control device that keeps the wings locked in position during normal usage. Doors will collapse and allow egress when smoke or fire alarms are activated, when a power failure occurs or upon activation of a special switch. Such functionality gives the building owner egress credit from most building code groups. Those same code groups require having a swing door adjacent to smaller revolving doors. Adding a low-energy operator, card readers and an electric strike or magnet gives the owner egress credit and ADA compliance.
Around the clock security can be easily achieved in a cost effective and prestigious manner with security revolving doors. As custom operation, finishes and construction are available from most manufacturers, consult with your local door distributor for special questions or applications.
Don Haerer is Revolving Door Product
Manager for Horton Automatics.
Phone 1-800-531-3111 or fax 1-800-531-3108.