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How to Avoid & Address Traffic Signal Knockdowns

How to Avoid & Address Traffic Signal Knockdowns

Imagine that a strong storm sweeps through a city and high winds knock traffic signals down from wires and off poles. In addition to creating unsafe driving conditions, these outages can slow emergency response efforts and require emergency personnel to direct traffic when their services might be needed elsewhere. These side effects can quickly add up in cost and social impact.

Let’s take a look at how to prevent knockdowns and improve the response times when they occur.

The Problem with Knockdowns

Traffic signals and signs that are knocked down by accidents, storms, or vandalism can be costly and dangerous. These knockdowns create unsafe driving conditions and unexpected budget overruns.

For example, the 2004-2005 hurricane season in Florida brought down more than 15,442 traffic signals statewide. At a cost of $80,000 to $100,000 a piece, these traffic signals are expensive to replace and place a financial burden on local agencies. Even a single traffic signal knockdown can be very expensive for a small town or city to replace.

Knockdowns can also be difficult to detect, especially if the knockdown occurs due to wind or vandalism.

Suppose that a stop sign is knocked down at a rural crossroads outside of city limits. There may not be enough traffic for someone to quickly report the missing sign, but a single failure to stop could lead to a serious traffic accident. It’s critical to detect these knockdowns as quickly as possible to avoid accidents and fatalities.

How to prevent traffic sign knockdown

How to Prevent Knockdowns

The first step in addressing knockdowns is preventing them through structural improvements. University of Florida civil engineering professor Ron Cook specializes in the effects of wind loading on structure anchoring. In 2009, Cook identified several causes for sign pole and signal failure and recommended structural changes to reduce or eliminate these defects.

Download our Checklist of Storm Response Tasks for Traffic Engineers to see how you should react following a dangerous storm.

The report included two key takeaways:

Polymer Wraps

The polymer wrap process involves digging around the concrete foundation of a traffic pole to a depth of 18 inches, wrapping a reinforced polymer around the concrete, and applying epoxy to keep it in place. When the epoxy dries, the foundation can be reburied. This reduces failures due to torsion that tend to take down signals in storms.

Single Wire

Two-cable systems are common for wire-suspended traffic signals, where the upper cable supports the weight of the traffic signals and the lower cable powers the signal. The problem is that there is considerable tension near the messenger cable where it crosses the hanger. Single-cable configurations can avoid this problem altogether and provide better wind resistance.

These traffic signal improvements can be done on existing traffic signal installations without the need to purchase any new equipment. By proactively addressing knockdowns, cities can spend just a couple thousand dollars rather than facing hundreds of thousands of dollars worth of damage following storms. This is especially true in storm-prone states.

How to Detect Knockdowns

The second step in addressing knockdowns is quickly detecting them before they cause serious issues. In most cases, cities rely on citizen complaints to report these knockdowns. The problem with this approach is that the problem may go undetected for a long time, such as when a stop sign is knocked down at a low-traffic (but potentially dangerous) crossroads.

At Applied Information, we have developed a new Internet-of-Things (IoT) product that detects when a traffic control device has been knocked down due to an accident, storm or vandalism and ‘calls’ for help. The knockdown sensor uses battery power and a cellular modem to send alerts to transportation system managers when the sensor is in an abnormal position.

Don’t forget to download our Checklist of Storm Response Tasks for Traffic Engineers to see how you should react following a dangerous storm.

The AI-900-032 Knockdown Detection Sensor connects to any Applied Information device and monitors it for sudden and unexpected changes in orientation. The sensor is self-calibrating, so no configuration is necessary. If the device has more than a 10-degree change that persists for more than 30 seconds, the sensor sends an alert to appropriate personnel via text, email, and the Glance dashboard.

Investing in Internet of Things

Knockdown detectors are just one application for the emerging IoT.

At Applied Information, we specialize in helping cities incorporate these emerging technologies into their existing traffic infrastructure rather than investing in entirely new equipment. You can realize the benefits of IoT technologies without high-capital investments and position your traffic infrastructure for the future of transportation.

Our Glance Smart City Supervisory System enables cities to manage all of their traffic and ITS assets in one easy-to-use web application. Rather than replacing existing assets, we provide cellular modems and cabinet systems designed to add connectivity to existing traffic signals. Over-the-air upgrades also ensure that the software is constantly kept up-to-date.

We are also preparing for the future of connected vehicles by ensuring that traffic infrastructure supports C-V2X technologies. These new capabilities are already being incorporated into existing vehicles and could help keep the roads safer for motorists, cyclists and pedestrians.

The Bottom Line

Traffic signal and sign knockdowns can be very costly and dangerous. While structural improvements can prevent knockdowns from high winds, IoT-powered sensors can help instantly alert city officials when an important sign is knocked down—even in rural areas where knockdowns may not be reported as quickly.

Applied Information’s Knockdown Detection Sensors can be added to any device, including traffic signals, crosswalks, school zone beacons and more. By incorporating these affordable technologies, your city can avoid potentially costly and dangerous situations.



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