As transportation professionals, we’re all deeply familiar with the regulatory landscape surrounding sign retroreflectivity. Whether you’re working under MUTCD requirements in the U.S. or adhering to the Ontario Traffic Manual (OTM) and O.Reg 239/02, maintaining retroreflectivity is now an established part of your asset management and compliance programs. But as our collective focus has centered on meeting these minimum standards, it’s important to reconsider whether readability is receiving the critical attention it requires to fully support driver safety.

Retroreflectivity: A regulatory success story

The industry’s progress in retroreflectivity is undeniable. Thanks to standardized sheeting, routine assessments, and evolving technologies—including AI-powered evaluations—agencies are better equipped than ever to ensure nighttime sign visibility. The safety rationale is clear: almost half of all traffic fatalities occur during dark hours, despite only a quarter of travel happening at night, and the nighttime fatality rate is roughly three times higher than during daylight. Upgrading to high-intensity sheeting alone has been shown to reduce crash rates by up to 38%1.

Both the MUTCD in the U.S. and the OTM in Ontario have set clear requirements for minimum maintained retroreflectivity. In the U.S., agencies must have a method in place to ensure compliance, while in Ontario, O.Reg 239/02 mandates annual inspection of regulatory and warning signs to ensure they meet OTM standards. These frameworks have raised the bar for nighttime safety and operational accountability.

Readability: The overlooked complement

Yet, as we all know, a sign’s visibility is only part of the safety equation. Readability—the ability for a driver to quickly and accurately comprehend a sign’s message—is not currently mandated, but it is critical. The OTM, for example, highlights that legibility, proper orientation, and physical integrity are essential for sign effectiveness, but these elements are often left out of formal compliance programs.

Consider the practical implications

A sign can be retroreflective and still fail its purpose if it’s faded, bent, tilted, or otherwise compromised.

Readability is defined by legibility from 20 meters, proper physical condition, and suitability for a 60-year-old driver at night—a demographic that now represents one-fifth of North America’s population, and whose visual needs increase sharply with age1.

Why readability matters now more than ever

With the aging driver population and the complexity of modern road networks, the margin for error is shrinking. Research shows that older drivers require up to eight times more light to read signage than those in their twenties, and that visible, readable signs lead to safer, more confident driving and fewer mistakes1. If we focus solely on retroreflectivity, we risk missing the broader goal: ensuring every sign communicates its message clearly, under real-world conditions.

Retroreflectivity ensures that a sign can be seen. Readability ensures that it can be understood and acted upon—especially by older drivers or in challenging conditions. Both are essential, but only one is currently regulated.

Moving forward: Integrating readability into best practice

Given that our agencies already have robust retroreflectivity programs, the next step is clear: integrate readability as a distinct, measurable element of your sign management strategy. This might include:

• Regular assessments of legibility and physical condition alongside retroreflectivity checks
• Prioritizing replacements based not only on reflectivity loss but also on diminished readability
• Training teams to recognize and document readability issues in the field
• Leveraging new technologies, including AI-powered solutions, to automate and scale readability assessments

As leaders in roadway safety, we have an opportunity—and a responsibility—to look beyond the letter of the law and address the full spectrum of what makes a sign effective. Readability is not a new concept, but it’s one that deserves renewed focus. By elevating readability to the same level as retroreflectivity, we can ensure our roads are safer and more accessible for all drivers, now and in the future.

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