Determining Reflectivity
How do I determine the best retroreflective sheeting for my signs?
Many of the parking signs, safety signs, and traffic signs available on TrafficSign.com are available in reflective aluminum. Similar to coated aluminum, reflective aluminum will not crack, rust, or chip and increases visibility during the night, inclement weather, and low light settings.
Like most things, not all reflective aluminum was created equally. In order to describe how reflective something is, we talk about its reflectivity. Reflectivity is a fairly simple concept, and simply refers to how efficiently a material redirects light back to its original source. In other words, the reflectivity of a sign greatly impacts how easily a sign can be read. In fact, reflectivity is so important for visibility that the Federal Highway Administration requires that all traffic warning, regulatory traffic, object markers, and guide signs must be reflective.
As previously mentioned, not all materials have the same reflectivity grade, and different types of reflective sheeting are ideal for different situations. Because of this, it’s a good idea to get a little more familiar with the different reflectivity grades.
Engineering grade sheeting (EG sheeting) is commonly used on parking and property signs. Signs that are made with EG sheeting can typically be seen from about 500 feet away.
High intensity prismatic retroreflective sheeting (HIP sheeting), isn’t quite as reflective as diamond grade, and is typically used on official traffic signs such as the ones that you see around your community. HIP sheeting is about three times more reflective than engineering grade sheeting, and signs that utilize HIP sheeting can be seen from about 1,000 feet away.
Diamond grade sheeting is the most reflective grade available, and is the best choice for use on roadways because it provides maximum visibility from the farthest viewing distances. In addition to being the most visible reflective grade, diamond grade sheeting is also the most durable, making it a great long-term investment.
Signs that utilize diamond grade sheeting can typically be seen from as far as 1,500 feet away and are 10 times brighter than standard engineering grade sheeting. This makes diamond grade sheeting the best choice for high traffic intersections and hazardous areas.
See the chart below for a breakdown of the different kinds of retroreflective sheeting:
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Type of Sheeting ATSM D4956 Type Brightness Visibility in Low-Light Conditions Ideal Use Case Engineering Grade (EG) Type I 1x 500 ft private driveways and parking lots High Intensity Prismatic (HIP) Type IV 3x 1,000 ft low traffic roadways Diamond Grade Type IX 10x 1,500 ft medium to heavy traffic roadways
To learn more about how to identify different kinds of retroreflective sheeting, visit the Federal Highway Administration’s traffic sign retroreflective sheeting identification guide.
To learn more about retroreflective sheeting designations and minimum maintained retroreflectivity levels, see Section 2A.08 of the Federal Highway Administration’s Manual on Uniform Traffic Control Devices.
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