Aluminum is a popular material for traffic safety signs because it is lightweight, durable, and reflective. The most common grades of aluminum used for traffic signs are 5052-H38 and 6061-T6. 5052-H38 is a high-strength aluminum alloy well-suited for use in areas with high traffic volumes. 6061-T6 is a high-strength, corrosion-resistant aluminum alloy that is ideal for use in marine and industrial applications.
The thickness of the aluminum sheet used for traffic signs can vary depending on the type of sign and its intended use. For example, regulatory and warning signs are typically made from thicker aluminum sheets for greater durability and longevity. On the other hand, smaller guide signs and informational signs may be made from thinner aluminum sheets. The weight of an aluminum traffic sign also varies depending on the size and thickness of the sign. For example, a typical 12x18-inch sign with a 0.080-inch thickness will weigh approximately 2 pounds..
In addition to the aluminum sheet, traffic signs are coated with a reflective material made from a thin layer of microscopic glass beads or prismatic reflectors that reflect light to the driver's eye, enhancing their visibility at night or in low-light conditions. The material's reflectivity is measured in the coefficient of retroreflection, which determines the sign's brightness when hit by a light source such as a car's headlights.
The MUTCD determines the reflectivity grade used for each type of traffic safety sign. The reflectivity of a traffic safety sign is measured in retroreflectivity. Retroreflectivity is the amount of light reflected back to the source of the light. The MUTCD specifies that traffic safety signs must have a minimum retroreflectivity of 70 candelas per lux (cd/lx) at 100 feet (30 m). The MUTCD specifies the reflectivity grade used for each type of sign.
Inspect signs regularly for damage and replace them if necessary. A trained sign inspector should conduct a nighttime visual inspection, where the retroreflectivity of an existing sign is assessed from a moving vehicle and signs that the inspector visually identifies as having retroreflectivity below the minimum levels should be replaced.
Replacing all signs in an area or a given type at specified intervals eliminates the need to assess retro-reflectivity or track the life of individual signs. Base the replacement interval on the expected sign life for the shortest-life material used on the affected signs.
Highway agencies may exclude the following signs from the retro-reflectivity maintenance guidelines described above:
Parking, Standing, and Stopping signs (R7 and R8 series)
Walking/Hitchhiking/Crossing signs (R9 series, R10-1 through R10-4b)
Acknowledgment signs.
All signs with blue or brown backgrounds.
Bikeway signs intended for exclusive use by bicyclists or pedestrians.
There are many benefits to using aluminum for traffic safety signs. Some of these benefits include:
Lightweight: Aluminum is lightweight, making transporting and installing traffic signs easy.
Durable: Aluminum is a durable material that can withstand the elements and heavy traffic.
Reflective: Aluminum is a reflective material, which makes it easy for drivers to see signs at night and in low-light conditions.
Cost-effective: Aluminum is a cost-effective material that can save money over the long term.
Recyclable: Aluminum is a highly recyclable material, which makes it an environmentally friendly choice for traffic and construction signs.
Installing and maintaining aluminum traffic and construction signs provide the necessary safety and directional information. Here are some best practices to follow to install and maintain them properly:
Install signs according to the applicable standards and regulations, including height, placement, and spacing. They should also be secured to posts with adequate hardware and to prevent theft or damage.
Inspect signs regularly to ensure they are clean, debris-free, and visible. Repair or replace any damage or wear immediately to maintain safety and visibility.
Clean signs regularly to maintain visibility. Clean aluminum signs with mild soap and water. Avoid abrasive cleaners, as they can damage the reflective surface.
Signs should be stored in a dry and secure location when not in use to prevent damage or theft.
As always, check with the MUTCD for updates and questions regarding a sign's message, reflectivity, choosing the correct size, or location. By following best practices for installation and maintenance, aluminum signs can provide reliable and long-lasting service, ensuring the safety and well-being of all road users.
