Security access systems and locks

There are several components to a security access control system. First you need a way for authorized users to identify themselves and/or unlock the door:

Keypads are common for single door security access and less expensive security systems. They’re easy to use but less secure, since users have a tendency to write down the entry code or to “lend” it to others. They also don't provide detailed audit trails unless you provide each employee with an individual code.

Another point to consider: how secure do you need the system to be? A basic system usually features a keypad or swipe card. Higher security applications may require multiple means of authentication (a card and thumbprint, for example) and include more redundancy. They're also more expensive.

Card readers are the most popular option in commercial access control. They're easy to use, and when cards are lost, it's a simple matter to deactivate them and issue new ones. They can also be combined with photo IDs for additional security.
Proximity cards, which can work from one inch to three feet from a sensor, are the most common. Because there's no contact between the card and reader, they're very reliable and suffer little wear and tear. They're also inexpensive. A specialized type of proximity card is the automobile tag, which allows access to a parking facility without requiring the driver to open their window or get out of the car. Automobile tags can work at hundreds of feet away from a sensor.
Security access systems can use magnetic stripe or barcode cards, as well, and these can be a money-saving option if you already use one of these technologies for employee ID cards.

Biometric systems rely on physical characteristics of the users for identification such as fingerprints, handprints, or even retinal scans. They are by far the most secure methods of access control. However, they are also considerably more expensive and can seem invasive to employees forced to use them constantly. They're also very unreliable outdoors, so they're not good for exterior security access.

Smartcards carry larger amounts information on the card itself, such as employee records or spending account balances, instead of just an ID number that references a database. They get some good press but haven't made much progress into access control — yet. In the future, as costs decrease and interoperability between different types of systems increases, their popularity may rise, but for now they remain a niche solution.

Other types of sensors can be used in free exit systems: loop detectors, photo cells or beams, and motion detectors all function by detecting a vehicle or person approaching an exit and unlocking a door.

Locks and gates
You'll also need locks that the security system can control electronically. The two main options for locking standard doors are electric strikes and magnetic locks. Electric strikes are generally cheaper and are better for free exit doors. They're also more appropriate for standard wooden or steel doors. Magnetic locks are better for aluminum and glass storefront doors, as well as for controlled exit situations and emergency exits.

Often, door hardware will include sensors that know when a door is open and can send an alarm signal if the door is opened without clearance. Systems can also sound an alarm if a security access door is propped open for a specified amount of time.

For restricting vehicle access, there are several options. The most secure are full garage-door openers. Almost as secure are various types of gates: sliding or swinging gates, depending on available space, move aside to let a vehicle into a parking lot. More common and much less expensive are barrier arms of wood, plastic, or metal that simply control the flow of traffic into a parking facility.