Overheight Vehicle Detection & Warning Systems

Trigg Industries began building and testing over height vehicle detection systems and warning devices in 1963 with its first installation in 1965 for the City of Newport News, VA. At that time numerous accidents were attributed to the 28th Street Bridge due to its angled construction over the roadway creating a situation where the bridge was a different clearance height depending on the direction of travel. The first installation of Trigg Over Height Detectors stopped the problem and did so for twenty years until the bridge was rebuilt. That first system was incandescent and required monitoring to insure bulbs were replaced as they periodically burned out.

In the late 1970's the technology was changed from incandescent to infrared which increased reliability and dramatically enhanced weather penetration. In the mid 1990's, visible red LED source detectors were introduced and in some patented systems, mixed with infrared LED source detectors to allow a system to look directly into a rising or setting sun without false alarming. Today, we have systems in continuous service for over thirty years.

It has always been the goal of the company to continuously refine our systems based on what works in the long haul in the field and under the unique conditions imposed at each installation site. To that end, we have worked extensively with our customers over the last fifty years to tailor the systems to individual requirements and specialized over height sensor applications. This is a standard of engagement that goes back to the very first days of the company. It is very common for us to review site plans and make recommendations that can save time, money, and reduce technical issues to a minimum.

We do not charge for reviewing installation plans and we also provide additional information in the Systems Overview section of this website for designing or explaining over height detection of overheight vehicles, over-height sensors and warning installation principles and guidelines to other planning team members.

Today, hundreds of major infrastructure owners use Trigg Industries Over Height Detection Systems and Warning Devices for bridges, tunnels, airports, parking structures, weigh stations, equipment yards, controlled access areas, and for many other applications. We manufacture both domestic and international versions and solar power capable systems.

A full range of capabilities and pricing accommodate the simplest needs as well as the most complex IT design requirements. Adjunct capabilities to include fault detection, camera interface, radio frequency or wi-fi link, loop detector interface, solar, custom warning signs in fixed or variable message formats, and back-up power supplies.

Trigg Industries is the oldest and most widely specified overheight vehicle detection systems manufacturer in operation. For over fifty years Trigg systems have served in the most extreme environmental conditions.

The Trigg Industries Patented Z-Pattern® dual beam over height vehicle detection system provides the most advanced ability to reject ambient light and virtually eliminates false over height alarms. Form C contact closure outputs are built into the sensor housing, simplifying installation and integration. Optional external controllers are available to enable additional capabilities including alternating flasher output and Ethernet connectivity. Whether it is specifically for over height detection or area incursion, Trigg Systems continue to evolve both from our own R&D and from the many long term working relationships we have with owners of our systems.


Since 1965 Trigg Industries has supplied traffic engineering products used in traffic census and data acquisition projects. Products on our website have stood the test of time in the widest range of highway environments where average daily traffic volumes may vary from five hundred to five hundred thousand vehicles per day. Trigg products have undergone the most rigid state and field-testing regimens. We supply traffic counting accessories and road tube to manufacturers of traffic counting devices as well as hundreds of traffic engineering departments across the U.S., Canada, and to our international clients.