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Security of Trailers at Warehouses

Cargo theft is a major problem in most parts of the country and leaving loaded trailers in outdoor areas can create an irresistible opportunity for thieves. Trailers can be broken into as they sit in the yard, or thieves may use their own tractor to drive off with an entire trailer. The high level of activity at many busy warehouses and distribution centers can make it relatively easy for a thief to slip in and out unnoticed.


Many warehouses and distribution centers now use "drop trailer" programs where inbound trailers are dropped off at the premises by the trucking carrier. Rather than waiting for the trailer to be unloaded, the truck driver parks the trailer in a designated holding area, unhooks it from the tractor, and drives off. In some cases, the facility has a "drop and hook" program, where after dropping off an inbound trailer, the driver can immediately pick up another loaded trailer that is headed outbound.


Drop trailer and drop and hook trailer programs have become increasingly popular over the years as they can provide operational efficiencies for both the warehouse and the trucking carrier. New safety regulations limiting the number of hours that a driver can work also provide a motivation for reducing the amount of time that a driver spends waiting for a trailer to be loaded or unloaded. Also, some seaports now try to reduce the number of trucks on the streets during daytime hours and achieve this by placing surcharges on trailers picked up or dropped off during peak hours. This incentivizes shippers to make deliveries at night and on weekends, often at times when the warehouse may be closed.


While drop trailer and drop and hook trailer programs may provide operational benefits, they increase security risks because trailers containing valuable merchandise are now left for extended periods of time outside of the warehouse. At one facility that we recently surveyed, inbound trailers containing merchandise could sit as long as three days in the receiving yard until such time as they could be unloaded.


To help combat trailer theft, the following is recommended:


Fully-Fenced Yard Area


The area in which trailers are stored should be fully-fenced using chain-link fencing or heavy-duty steel security fencing. A minimum fence height of eight-feet is suggested. Where permitted, the use of barbed-wire or razor-ribbon along the top of the fence should be considered.


Visibility should be maintained around both the inside and outside of the entire perimeter fence line. A "clear zone" of at least ten feet should be provided on both sides of the fence. Pallets, trash containers, and equipment should be kept out of the clear zone. Landscaping should be trimmed so that it does not obstruct visibility along the fence line.


Controlled Entrance Gates


Vehicle access to the yard area should be made only through controlled entrance gates which are staffed by a security officer during hours of operation. The use of barrier arm gates, which are raised and lowered by the security officer, are recommended to provide positive control of traffic in and out of the yard.

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Example of Barrier Arm Gate


Security Officers


Warehouses and distribution centers that operate on a 24/7 basis should have security officers on duty at all times. Security officers should be provided at each of the entrance gates, and in addition, at least one officer should be available to make roving patrols.


Security officers assigned to work at the entrance gates need to have a good understanding of shipping, receiving, and trucking operations in addition to having general security knowledge. Because of the special skills required here, officers should be specifically qualified and trained for this type of post.


Facilities that do not operate on a 24/7 basis should have security officers on duty during hours of operation. In addition, it is highly recommended that at least one security officer be on duty at times when the facility is closed.


Gate Operating Procedures


Comprehensive procedures for controlling traffic in and out of the yard area should be established. The person responsible for security should work closely with the management teams responsible for shipping and receiving operations to make sure that procedures are both operationally efficient and provide good security.


A traffic management system should be put into place so that the security officer at the gate is made aware of all expected deliveries and outgoing shipments. This system can be computer-based, or can consist of written sheets that provide details on all expected inbound and outbound shipping activity.


All vehicles should be required to stop at the gate when entering and exiting the yard area. For incoming traffic, the security officer should confirm that the delivery is being made to the right address, and verify that the delivery is expected. If the delivery is legitimate, the officer should then log the company name, driver's first and last name, tractor number, trailer/container number, and seal number. The driver's license of each driver should be examined to confirm identity.


For outbound shipments, a similar procedure should be followed: the security officer should verify that the shipment is authorized, and log the company name, driver's first and last name, tractor number, trailer number, seal number and note whether the load is full or partial. Drivers removing empty trailers/containers should be required to present a receipt that shows trailer/container number, location where it was grabbed from, and the driver's signature and date. The security officer should verify this information and then inspect the trailer/container to be sure that it is empty before it is allowed to leave.




Good lighting within the yard area and at the entrance gates is essential for both safety and security. It is recommended that the light levels within the overall yard area be a minimum of one foot-candle (FC). Recommended light levels at the entrance gates are 10 to 20 FC. The lighting in all areas should be evenly distributed. Having poorly illuminated areas directly adjacent to brightly illuminated areas can create shadows and blind spots. We recommend that the exterior lighting system be designed to provide a uniform level of lighting throughout the site, with a uniformity ratio no greater than 4:1 (average: minimum).


Video Surveillance Systems


It is recommended that a video surveillance system be provided to observe and record activity throughout the entire yard area. In addition, dedicated cameras should be provided specifically to view the fronts and sides of vehicles and they enter and exit through the entrance gates. The purpose of these cameras is to capture license plate numbers and vehicle and trailer identification numbers. Because of the complexities of reliably capturing this level of detail using video cameras under varying lighting conditions, a qualified security consultant or security systems integrator should be hired to design this type of system for your specific facility.


It is recommended that cameras used at entrance gates be recorded at the frame rate of 15 frames per second (FPS) or greater, and that all recorded video kept kept available for a minimum retention period of 90 days.


Trailer/Container Parking


When possible, trailers/containers stored on site should be backed against a solid wall to prevent the rear trailer doors from being opened by unauthorized people. If this is not possible, similar protection may be achieved by backing trailers against a fence or parking them back-to-back.


Trailer Locking Devices


There are numerous devices on the market designed to prevent the unauthorized movement of trailers. These devices include king-pin locks, which mount to the trailers king-pin to prevent a tractor's fifth-wheel from attaching to it; glad-hand locks which attach to the trailer's air brake line to prevent the trailer from being moved; and landing gear locks which prevent the trailer's landing gear from being raised.


It is recommended that trailers containing merchandise that will be stored for extended periods in the yard area be equipped with some type of trailer locking device. While these devices are not perfect and can eventually be compromised by a motivated thief, they do serve as a deterrent and increase the amount of time that it takes for trailer to be removed. In addition to providing security benefits, trailer locking devices can also increase safety and prevent the unintentional removal of trailers by the wrong carriers.


All locking devices should be labeled with a unique identification number. A written log should be kept that indicates when each locking device is installed or removed from each trailer and by whom.


Example of  King Pin Locking Device



Trailer Alarms


The use of security alarms on trailers should be considered when a security officer is not present on site at all times and/or when trailers contain cargo that is of particularly high value. Because in most cases, trailers/containers are provided by the shipping carrier or other party, they cannot be equipped with permanent alarm systems. To provide alarm protection, two strategies are commonly used.


The first strategy is to use a simple hardwired connection to the trailer. This connection is temporarily attached when the trailer arrives and is usually connected to an unused zone on the warehouse's regular intrusion alarm system. Most often, a detachable cord is looped though various parts of the trailer to prevent the trailer from being moved without setting off the alarm. Temporary door contact switches may also be attached to the trailer doors.


The second strategy is to use a self-contained alarm system within the trailer itself. These systems are placed within the trailer when it arrives and include motion and movement detection capabilities. These systems typically use the cellular telephone network to communicate and are capable of directly notifying security personnel when an intrusion attempt is detected. Some portable alarms also include a GPS tracking feature that can help locate trailers after they have been stolen.

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Example of  Self-Contained Trailer Alarm

If you have questions about this article, or need help in planning security for your warehouse or distribution center, please contact us.


(Also see related article Security of Warehouses and Distribution Centers )

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