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Reducing Overheight Collisions: Get to Know Your Overheight Warning System Options

Collisions between overheight vehicles and low-clearance structures – bridges, tunnels, parking structures and more – are both common and costly. Proactively alerting overheight vehicle drivers of an impending collision can drastically reduce incidents and boost safety for all road users.

While overheight warning systems make this possible, it’s important to right-size the system and leverage the most effective configuration.

To help, I’ve laid out exactly how overheight warning systems work, your various configuration options and what to keep in mind to maximize your return on investment.


How Overheight Warning Systems Work

Systems like the TAPCO Overheight Warning System feature infrared sensors mounted on both sides of a roadway in advance of a low-clearance structure that detect overheight vehicles.

When detection occurs, the system uses wireless radio communication to activate flashing LED-enhanced warning alerts – typically signs or beacons – to warn the driver they are about to collide with a low-clearance structure. Crucially, the alerts only flash when an overheight vehicle is approaching, commanding drivers’ attention far more than traditional static signs.

Systems are recommended to be placed in advance of an alternative route to provide safe passage for overheight drivers.

In a survey by the Alaska DOT, every state using overheight warning systems reported fewer overheight incidents.



Rightsizing The Configuration

Learn how to identify the best configuration to fit your specific needs.

1. Activation Options

The infrared sensors that activate overheight warning systems can be activated in a few different ways, depending on the application.

Single-beam sensors are used in parking garages and certain off-road, closed applications.

Dual-beam sensors are used on roadways with one-way traffic where directionality is not needed.

Dual-directional sensors are used on roadways with two-way traffic to activate systems only when offenders approach from a specific direction.

Sensors account for the height of low-clearance structures and the posted speed limit. The TAPCO system is capable of covering up to 150 feet between sensors and detecting vehicles traveling up to 75 miles per hour.

Reducing False Positives

For maximum detection accuracy, select a system from a vendor like TAPCO that has dual-directional sensors – also ideal for gathering system data – and requires an object be at least two inches wide to activate the system. This prevents snow, hail, birds and more from causing false positive detections.

2. Warning Alert Options

BlinkerSign® LED-Enhanced Signs

Signs featuring amber LEDs in the sign face that flash upon activation, such as BlinkerSigns, are a popular alert option. The LEDs dim based on ambient light and are MUTCD compliant.

BlinkerSigns can be ruggedized to withstand extreme weather conditions, falling rocks, debris and more.

BlinkerBeacon™ LED-Enhanced Beacons

Overheight warning systems can also leverage round amber LED beacons that flash upon activation. At TAPCO, these are eight-inch or 12-inch beacons called BlinkerBeacons. They can be dual horizontal or dual vertical, depending on the needs of the location.

The LED beacons also dim based on ambient light and are MUTCD compliant.

Audible alerts

Some overheight warning systems can activate audible alerts upon detection, providing a second way to notify overheight drivers of an impending collision.

3. Power Options

Solar Power

Solar-powered systems are ideal if:

  1. The installation location is too far from an AC power grid
  2. The costs of connecting to an AC power grid – trenching and metering, for example – are prohibitive
  3. Long-term power usage is a concern due to cost or the environment

TAPCO can design overheight warning systems to fit any location’s power needs, offering solar panels with varying degrees of wattage and battery capacities, as well as self-contained top-of-pole solar cabinet options.

Right-Sizing Solar Panels

downloadCritical solar factors, such as direct normal irradiance and global horizontal irradiance, vary depending on the system’s location.

To ensure the right power configuration, get a solar calculation.



AC Power

AC-powered systems are ideal if:

  1. The locations have lower light levels due to tree shading, heavy cloud coverage and/or the geographic region
  2. An AC power grid is readily available

The TAPCO Overheight Warning System can use 120VAC or streetlight power, enabling agencies to tap into existing infrastructure for power.

Solar and AC Power Combination

A combination of both solar and AC power is available from TAPCO and some other vendors.

For example, Athens-Clarke County, Georgia placed AC-powered TAPCO Overheight Warning System alerts near large oak trees that cast significant shadows and solar-powered alerts in sunny spots. 

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4. System Enhancement Options


Some systems can include high-definition cameras that capture images and/or video of overheight system activations, enabling authorities to monitor activity and see the vehicle that triggered the activation.

Another option is license plate recognition (LPR) cameras, which provide documentation to road operators for overheight violation enforcement.

BlinkLink® Event Management Software

The TAPCO Overheight Warning System can be enhanced with BlinkLink®, an easy-to-use, cloud-based software application for agencies to remotely manage and monitor overheight warning systems and other Intelligent Warning Systems.

BlinkLink® can be integrated with third-party software systems via an application programming interface (API).

Connected Vehicle Interface

Forward-looking government agencies can add another layer of safety with a Connected Vehicle Interface, which communicates information about upcoming low-clearance structures and other hazards via connected vehicle roadside units, delivering in-vehicle alerts to drivers of connected vehicles.

Maximizing Return on Investment

Overheight warning systems can be incredibly cost effective and cheaper than the alternatives.

Overheight vehicle collisions cost an average of $200,000 to $300,000, and total costs often climb even higher. Thus, if an overheight warning system prevents even one collision, it can easily pay for itself.

In addition, operation and maintenance (O&M) costs for these systems are low. An Alaska DOT survey found that most states with overheight warning systems experienced negligible O&M costs and few maintenance concerns, with 45 percent reporting none at all.

The TAPCO Overheight Warning System was even found by the Georgia DOT to be “very durable” and free of any installation limitations or sensitivity problems, which ensures ownership doesn’t come with hassle and extra expenses.

Most importantly, overheight warning systems have the power to save lives, providing a value that simply cannot be measured.

These solutions are included on TAPCO's competitively solicited and publicly awarded cooperative contract, available through OMNIA Partners. For full contract documentation, click here