Preventing Tailgating at Parking Garage Entrances

One of the biggest security vulnerabilities at many buildings is “tailgating” at the overhead door at the parking garage entrance. Tailgating is when a criminal sneaks into the parking garage just after a vehicle enters or exits the garage.

This can be a particular problem at multifamily properties such as apartments or condominiums, where property managers often report that tailgating through the garage entrance is their number one security problem.

Once in the garage, a criminal can break into cars or storage rooms to steal property or linger in the garage waiting to carry out an assault or robbery. Also, if the building has not been well-designed from a security standpoint, an intruder may also be able to gain access to some or all other floors of the building from an elevator or stairway (see Security Problems Related to Stairways).

Drivers are usually in a hurry when they enter or exit a garage and most often give no thought as to who may enter the garage after they drive in or out. Many overhead doors can take 30 seconds or more to close, and this time is often reset when the safety beam is broken as the door begins to close. This gives an intruder plenty of time to enter the garage. 

Solutions to the tailgating problem at garage entrances can range from the very simple to the very complex. Here are some suggestions:

User Security Awareness

One of the best and least expensive ways to solve this problem is through user security awareness. Most intruders don’t want to be spotted when they enter the garage and wait until the vehicle drives off before entering. If the user waits until the overhead door fully closes before driving off, this will discourage the majority of intruders from entering.

Although this solution is simple and effective, it conflicts with natural behavior, as most users are reluctant to wait for the 30 seconds or so it takes for the door to close. To overcome this requires an ongoing campaign of user security awareness training delivered through written communications, in-person sessions, and using online resources.

Painting stop lines on the pavement showing where drivers are to wait and posting prominent signs that say “Wait for Door to Fully Close Before Driving Off” can help to encourage proper behavior.

Some condominium buildings have provisions in their bylaws to impose fines against homeowners who repeatedly ignore the “wait for door to close” policy. Video recordings of the cameras that view the garage entrance are reviewed in order to identify violators. Warnings are issued for first offenses and fines are imposed for subsequent offenses.

Improve Visibility at Garage Entrance

Poor visibility in the area around the garage makes it easier for an intruder to hide waiting for an opportunity to enter. Steps that can be taken to improve visibility include:

• Trimming or removing shrubs and trees near the garage entrance.

• Relocating items such as trash dumpsters or utility sheds away from the entrance.

• Providing good lighting outside of the garage entrance. (5 to 10 footcandles (approximately  50 to 100 lux is suggested).

• Painting the wall beside the garage white or another bright reflective color to make people stand out better and improve the effectiveness of lighting.

Reduce Door Open Time

The longer the door stays open after a vehicle passes through the greater the opportunity for an intruder to enter. Unless there are special circumstances the time that the door remains open before closing should be set to eight to ten seconds, enough time for a normal vehicle to clear. Keep in mind that the door’s safety devices (safety loop and safety beam) should prevent the door from closing on a vehicle still under the door, so there is generally no need to provide excessively long times for safety reasons.

Reduce Range of Wireless Controls

Many wireless radio controls can operate at a range of 150 feet or greater. Users sometimes use their wireless transmitter when they are a considerable distance away from the door so that the door is fully open when they arrive. This allows an intruder standing outside of the door to enter unobserved. 

A good policy for overhead door security is “don’t open it if you can’t see it”. To help enforce this policy, wireless radio controls should be adjusted so that they only open the door when the transmitter is within a short distance of the receiver. This can often be accomplished by shortening or repositioning the antenna on the receiver.

Consider Use of High-Performance Door

Many overhead doors, particularly larger doors and curtain doors, are inherently slow to open and close and there is little that can be done to change this. 

For buildings who want to improve security and are willing to make a substantial investment to do so, there are special types of doors available that operate much faster. These doors are known as high-performance doors or high-speed doors and can open and close in as little as six seconds or less. These doors can greatly reduce tailgating.

High-performance doors are relatively expensive, typically costing between $50,000 to $75,000 USD. Adequate space (~ 3’ to 4’) is also required above the door to install the door operator and this space is sometimes not available in all buildings.

Using Gates Interlocked with Overhead Door

To enforce the “wait for door to close” policy, some buildings install barrier arm gates on both the inside and outside of the overhead door. When a driver uses a wireless transmitter or other device to open the door, the barrier gate on the outside is raised and the overhead door is opened. The driver drives through the overhead door but then must wait at the barrier gate inside of the door until the overhead door fully closes. Once the door is closed, the inside barrier gate is lifted, allowing the driver to proceed.

This solution typically costs between $15,000 and $25,000 USD; however, the biggest limitation is usually not money, but the lack of available space. There must be adequate space between the overhead door and barrier arm gates on both sides, and it is rare to find this much available space in most existing commercial and residential buildings. 

Tailgating Detection Systems

There are numerous tailgating detection systems now on the market. Most of these use video surveillance cameras in conjunction with some form of video analytics software, installed either in the camera itself or on a central server. 

The software uses artificial intelligence to detect when a person or vehicle follows behind a legitimate user and sounds an alert when a violation is detected.

Tailgating detection systems work best when a facility has real-time monitoring and response capabilities. For example, when a tailgating alert occurs, an operator at a monitoring center would be immediately notified. The operator could then assess the situation, and if necessary, dispatch an onsite security officer to respond.

We feel that these systems provide limited value at facilities that don’t have a real-time monitoring center and don’t have a security officer onsite to respond. 

Some facilities use an off-site active video monitoring service (also called remote guarding service) to provide monitoring of some or all of their cameras. Alerts from a tailgating detection system could be sent to this service. 

The normal procedure would be for the operator at the monitoring center to assess the situation, and if an intruder was spotted, the operator would use a paging speaker to ask the intruder to leave. If the intruder failed to do so, the operator would dispatch a security patrol officer to the site to investigate. In many cases, the intruder would probably have already committed his crime and be long gone before the security officer arrived.

Have questions about ways to prevent tailgating and improve the security of your parking garage? Please contact us.