Jun 011991


Roadway gate systems come in many types, sizes, variations, and prices. Preliminary information about gates, gate operators, access control systems, exit systems and emergency access systems are described below.


Gates come in many designs and styles. A logging road gate will surely meet your requirements regarding vandalism resistance, a chain link gate will make the accountant happy, and an ornamental iron gate can make a statement on a variety of levels. Each have their own characteristics related to security, space requirements, ease of operation, and aesthetics. Tied closely to these choices is the gate’s operation system. Gates can be hinged on the side, swinging in or out like the front door of your house, pivot from the side and rotate up like the barrier arm at the entrance to a parking garage or it can slide to the side.



The gate operator opens and closes the gate. The type and size of gate operator changes with the type and size of gate. The gate operator should have some type of battery back-up system allowing the ability to function in the event of a power outage. There are two ways of functioning in the event of a power outage, “Fail Safe” and “Fail Secure”. Fail Safe automatically opens the gate when the power goes out, then automatically resets and closes upon restoration of power (it should be noted that since the Fail Safe configuration includes automatic operation, it is important to have a “safety system” in place). Fail Secure keeps the gate closed in the event of a power outage. The entire gate operator/control system can be equipped with a “full function” battery back-up, allowing all of the system components to function if the power goes out. Some gate operators are designed with built-in batteries, which can be utilized to provide Fail Safe function. Other gate operators can have a battery back-up added to provide Fail Safe function. Most gate operators are equipped with an internal timer that can be turned on to automatically close the gate after an adjustable time delay. Many gate operators are equipped with an inherent reversing device, which will automatically stop or reverse if the gate contacts an object during operation.



An access control system is a device that opens a gate for resident or visitor. They come in several variations. The most popular methods for sending an “open” command to the gate operator are as follows:

a) Radio transmitters and receivers (similar to those used for opening garage doors) can be used, and are certainly the most common access control device. These can also be supplied in a multi-button configuration – one button will open the gate, another button will open the garage door. Radio systems come in several security levels. With some systems each transmitter (clicker) has a unique coding, so that if that transmitter is lost or stolen, access for that transmitter can be denied.

b) Preprogrammed entry codes can be entered onto a keypad (also called a keyless entry system) adjacent to the gate. Most programmable keypads are capable of storing at least 20 entry codes; and the codes can be assigned “time zones”, so that some codes will open the gate only Monday through Friday from 8am to 5pm, and other codes will open the gate any time.

c) A card reader, utilizing a credit card sized card, reads the code programmed onto the card’s magnetic strip. Card readers come in several variations. Some card readers need to have the card slid into a reading head, similar to those used at a gas pump or at the supermarket. Others, termed proximity card readers, require the user to simply get the card near the card reader (up to eighteen inches away); others may require the user to place the card on the reader. The advantage of proximty cards is that the magnetic strip doesn’t get scratched and damaged with use. Each card has a unique code so that, if it is lost or stolen, access can be denied.

d) A “telephone entry system” allow visitors at the gate to call and speak with a resident over the telephone, who may then allow them access by pressing a button on their phone or the resident may pick their phone and press buttons that will hold the gate open until they repeat the process and close the gate. The system can be programmed to automatically open the gate and hold it open for a set time. It also comes with a keypad for entry codes. Most have two relays so that a second gate, closed circuit television camera or landscape lights can be controlled. Some are computer programmable, making it considerably easier to program, and have transaction buffers, which store the date and time of each entry code’s use.



A safety system, sometimes called a reversing system, prevents the gate from closing if there is an obstruction in the gate’s pathway. It should be noted that the safety system does not prevent the gate from opening. This is done so that, in an emeragency, a malfunctioning safety system won’t prevent egrss. Safety systems are alway a good idea, but are especially important if the gate’s timer is set to automatically close the gate. The different types of reversing systems all have pros and cons. For example:

a) The most common vehicular sensing system is a “loop detector” which senses the change in the earth’s magnetic flux as a mass of metal (a vehicle) passes over wires which have been buried in the roadway. Loops are placed on both sides, and sometimes directly below the gate, holding it open for a vehicle stopped, or a procession of cars in the gate’s pathway.

b) Photo-eyes sense the presence of persons or vehcles with the use of a light beam that crosses the path to be protected. “Breaking the Beam” sends a signal to the operator that something is in the way.

c) Edge-detectors, sometimes called soft edges, are used to stop or reverse the gate upon contacting an obstruction.

d) Flashing lights, a rotating beacon, or an audible alarm can also be used to warn persons in the area that the gate is moving.



This system automatically opens the gate for an exiting vehicle, and is used if the gate operator’s timer is set to automatically close the gate. It comes in two variations, standard and direct-sensing. The standard exit detector utilizes a single loop detector. (the disadvantage of this system in a two direction roadway is that the gate will re-open as an entering vehicle passes over, increasing the possiblity of unauthorized entry by a vehicle closely following) The direction-sensing exit detector utilizes two loop detectors, opening the gate for an exiting vehicle only. Other devices, such as push buttons, keypads, and photo eyes, can be used to open the gate for exiting vehicles, but the most common is the loop detector.



The emergency access system opens the gate for Fire Department and Law Enforcement Personnel.

a) The Knox system allows only fire department access, utilizing a special key which is kept in fire engine and paramedic vehicles.

b) The strobe system (which is the system emergency vehicles use to control traffic lights) allows access to any emergency vehicle equipped with a strobe emitter, which includes most emergency vehicles in our area.

c) The siren-operated-sensor allows access to any emergency vehicle equipped with a “yelp” function on their siren, which is also on most emergency vehicles in our area.

There are other options available such as closed circuit television (CCTV) and automatic vehicle sensors. Other considerations when installing a gate and a gate operating system is electrical supply access, telephone access, road work, masonry work, and landscaping.

Gate Systems Design

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