Signal Spotlight: Traffic Signal Cabinet Security


Signal Spotlight: Traffic Signal Cabinet Security

Traffic signal cabinets are typically locked to prevent equipment damage or theft and, more importantly, to protect road users from the safety and liability risk of a malfunctioning or non-functioning signal due to tampering. Traditionally, traffic signal cabinet locks use a standard #2 key. This provides a level of convenience as signal technicians, engineers, and contractors can all access the cabinet. However, these keys can easily be purchased on the internet. This means anyone can obtain a #2 key and access any number of traffic signal cabinets with the agency operating the traffic signal left unaware. If an employee drops their key, an individual could pick it up and use it to tamper with or steal cabinet equipment.

With the introduction of electronic controllers with networking capabilities, the role of traffic signal cabinets has changed. In the past cabinets simply housed electromechanical equipment, but now they are used to provide a vital level of network security. Increasingly, municipalities are connecting traffic signal controllers to their computer networks to allow for central control of the signals and monitoring of camera feeds. The need to protect the computers and sensitive information on these networks has prompted manufacturers to produce new security solutions that can be installed in new cabinets or retrofitted in existing cabinets.

One option for increasing security is a high-security mechanical lock. To provide convenience, these locks can be keyed so that all of the traffic signal cabinets in a system use the same key. These locks are usually designed to be resistant to the elements and to lock picking. One consideration with this type of lock is the management of keys. If a vendor requires access to the cabinet, the agency must provide them with a copy of the key or travel to the intersection to provide access.

Another option is an electromechanical lock. These locks use an electronic key to provide access control using programmable keys. Some of these keys require recharging, while others are designed with built-in batteries. Some batteries are replaceable, while other keys are designed with non-replaceable batteries and must be disposed of and replaced when the batteries die. Some manufacturer software provides an audit log for monitoring access to the cabinets, and there are systems that allow for timed access to the cabinet during pre-set time periods. If keys are lost, they can be reprogrammed using the software to prevent access to the cabinet. These systems have the benefit of increased accountability and security but can be inconvenient if a key loses its charge or the battery dies.

A third type of access control relies on passcodes or RFID proximity cards to disengage a solenoid and provide access to the cabinet lock. Once access is provided, a standard #2 key can be used to open the lock. A benefit of this type of system is that it does not require a special key that needs to be charged. One thing to note about these systems is that they are powered through the cabinet and can default to either the cabinet being unlocked or the cabinet being locked until power is restored.

However an agency decides to limit access to its traffic signal cabinets, it is important to involve any stakeholders who may need access to the cabinets. This will ensure that the system will meet all of the agency’s needs, securing the cabinets while allowing necessary access.

The T2 Center does not endorse any particular product or manufacturer and offers the above examples for informational purposes only.

About Connecticut T2 Center

The Training & Technical Assistance Center at UCONN provides education and technical assistance to members of Connecticut's Transportation and Public Safety Community, including municipal public works directors, street and road maintenance superintendents and staff, city and town engineers, Connecticut Department of Transportation employees, transportation planners and law enforcement professionals serving as legal traffic authorities. We are Connecticut's LTAP Center
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