Get Into the Swing of Gate Access Control

Experienced vehicle access control integrators know that parking applications are very different from traditional building access control. When designing these systems, an integrator must remember that every vehicle driver is in command of a heavy, potentially deadly piece of moving machinery.

Although a driver does not have as much flexibility as a person on foot, he or she has the potential to purposefully or inadvertently inflict major damage on a facility, pedestrians or other vehicles. A terrorist on a suicide mission may attempt to crash a vehicle laden with explosives through the gate and damage a building, along with its occupants. Another driver without any harmful intentions may cause damage simply because he or she is distracted and lets go of the brake at the wrong time.

Therefore, safety and – if the facility being protected is high-risk – security are two major considerations.

Add to that the fact that a parking lot or structure may have cars and trucks waiting in line to enter or exit, and traffic management becomes a big issue. Another aspect that must be taken into account is whether or not pedestrians should be barred from entering the parking structure.

These factors and the latest technology should be considered when determining which gates and access systems best meet the needs of each customer.

Greater Speed, Less Maintenance Make Gates More Attractive

In recent years, gates and gate operators have evolved at an extraordinary pace. According to Dan Floyd, president of Columbus, Ohio-based Signature Control Systems, “Rather than the simple horse-powered motors with gear reducers, we’re seeing a lot more direct-drive and hydraulic systems.” Because of these and other advances, barrier arms are able to move at much greater speeds, so backed-up traffic isn’t as much of a concern as it was only a few years back. Gates can also be heavier and longer.

Additionally, many gates and gate operators are now designed so maintenance is not as major a concern. Because of the decreased need for upkeep, heavy use (e.g. 1,000 entrances/exits per day) is less of an issue than before.

Taking into account the fact that the events of Sept. 11, 2001 made everyone more aware of their vulnerabilities, gate and gate operator advances have come on the market at the right time. Management at airports, water treatment plants, courthouses and other government buildings are reevaluating their security strategies and, in some cases, installing crash-rated gates if none were there previously. Even medium- and low-risk facilities are taking a second look at their perimeter security and gate systems.

Slide, Swing Gates Prevent Pedestrian Passage

When selecting a gate and gate operator for a location, a dealer/integrator must consider whether or not pedestrians will be allowed to pass the gate unchecked. If a person is not allowed free access, then slide or swing gates may be most appropriate. These products can be crash-rated for high-security applications, such as prisons and airports. Gated residential communities also prefer swing or slide gates.

Both types of gates can have electro-mechanical or hydraulic operators. One of the biggest pitfalls of swing and slide gates, however, is that both are slow. A slide gate usually only moves one foot per second. Because of this, tailgating can be a major problem.

Still, chain-driven gates can be noisy and not as attractive as other types of operators. If appearance is important to a client, then a swing gate may be the best option. Swings can have pickets and other ornamentation without violating UL 325 or the ASTM Int’l Standard Specification for Automated Vehicle Gate Construction (for more on these subjects, see sidebars on pages 40 and 46).

Another advantage to swing gates is, if they are hydraulically driven, they can lift up to clear a curb or driveway.

Vertical Lift Gates Often Save Space and Time

When installing a slide or swing gate, an installer must be certain that there is enough space for proper operation. With a slide, there must be room to the side of the roadway. With a swing, there must be room in the direction where the gate is swinging.

If space is limited, then a vertical lift gate may be most appropriate. These units are often used in parking garages where space is only available above the driveway. Another plus to this type of system is that it may take less time to open than a slide gate because it moves vertically and has less area to cover. For example, with a 40-foot-wide driveway, if the gate only must be raised 20 feet, the amount of area that is covered is reduced by 50 percent.

Barrier Arms Offer Speed, Durability for High-Traffic Applications

Slide, swing and vertical lift and pivot gates all prevent pedestrians from entering a parking lot or facility. If guarding against pedestrian passage is not an issue, then barrier gates may be the appropriate solution. This type is faster (some can go up or down in less than a second), so traffic backup is averted. Very often, barrier arms are installed in revenue-generating or employee parking lots or structures where the primary concern is control of vehicles. Barrier gates can also be crash-rated for high-risk facilities.

Dual-Gate Systems Provide Speed and Security

Still, if a client wants both the speed of a barrier arm as well as the protection against pedestrian passage that slide and swing gates provide, an integrator may want to install a dual-gate system. Usually, these types of systems have a slide gate with a barrier arm in front of it.

In high security installations, such as military bases, an entrance that is manned often has a slide gate that is open during the day (during heavy traffic hours) with a crash-rated barrier arm preventing unauthorized vehicle passage. During evening hours, when the entrance is not supervised by military personnel, the slide gate is closed.

Loops Designed to Prevent Vehicle Damage

Regardless of the type of gate used, some form of ground loop is required to keep the gate from crashing into or on the vehicles. A loop is a coil of wire that is embedded in the driveway in a rectangular formation. This wire creates a magnetic field, so when metal from a vehicle is introduced into that field, it changes the inductance of the loop and provides a contact closure. That closure, depending on the system’s design, determines what the presence of the vehicle on the loop will do. Some loops open or close gates. Others prevent gates from closing.

The size of the loop correlates with the detection area’s height. A normal-sized loop (21/2 feet X 6 feet) will handle most cars and SUVs. Larger loops (4 feet X 9 feet) may be required for trucks. It should be noted that loops only detect vehicles and not pedestrians.

Be Mindful of Pedestrian Safety, UL 325 and ASTM Standards

When it comes to safety, even if a pedestrian gate is installed and clearly marked, inevitably, someone will attempt entry via the vehicle gate. Safeguards then, must be in place to prevent pedestrian entrapment, and an integrator should be thoroughly familiar with UL 325.  Photo eye and contact sensors are just some of the measures mandated by UL 325. Other details pertaining to gate construction can also be found in the ASTM Int’l Standard Specification.

When installing any gate system, a method to allow emergency vehicle access must also be provided. When power is available, fire department lock boxes, key switches, and siren, yelp or strobe light sensors will enable emergency access. Some cities may also require a battery back-up system that will automatically open the gates should a power outage occur.

If power is disrupted, a gate operator should provide some means of manual disconnection. This aspect is also covered in UL 325.

Gate and gate operator technology, as wel

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