Reflective Road Signs Materials Traffic Sign Sheeting Maker

What are traffic signposts made of?

Concrete Sign PostThat depends. Depends on whose jurisdiction the signs are in, for instance.

If the sign is located on the Interstate Highway System, the USDOT works with the State DOT to determine how sign systems are constructed. The USDOT allows some variation in the way signs are posted.

Depending on Your Local Jurisdictions

In some jurisdictions, wood posts are used to post some types of signs, although wood seems to rarely be used for the big green and white wayfinding signs anymore. Most of the time traffic signposts are constructed of welded and/or bolted together with steel frames, and even the smaller signs now, at least in our area, are mostly posted with steel posts.

However, I still see, in housing developments or commercial developments, that pressure-treated wood posts are allowed. I personally recommend the pre-punched galvanized steel posts and post sleeves over wood or the U-channel posts that are used by those trying to keep costs down.

What’s the difference between a flat aluminum and an extruded aluminum street name sign?

Flat Aluminum Signs

Extruded Metals of AluminumFlat aluminum is pretty self-explanatory and is easy to describe, so I’ll do that first. Flat aluminum is actually extruded as well, but it’s extruded into flat sheets, and most traffic control signs that are constructed of flat sheet aluminum range in thickness from .080” to .25”, although most of the time, in my experience, once the thickness moves past .125” with flat sheets, either a supporting frame buttresses the sign or we use extruded aluminum.

Extruded Aluminum Signs

Extruded aluminum signs are usually extruded in channel-shaped sections, sometimes with “ribs” that support the extrusion in high wind conditions. The extrusions are often “stacked” one on another and bolted together, then bolted to a galvanized steel framework that holds the whole sign together.

Stop signs, speed limit signs, school zone signs, Parking Signs, etc., are almost never extruded but are flat panel signs. The extruded signs are usually used only for large wayfinding signs, like the ones on I-75 telling you how far it is to Atlanta, Georgia or Lexington, Kentucky, or I-90 telling you how far it is to Seattle, Washington.

One of the major areas in which progress has been made is reflection. Road signs today are far more reflective than their lackluster predecessors. Thanks to recent improvements, high-quality signs glow at the sides of roads like proverbial North Stars, and as a result, it is much safer to drive at night than it was in the past.

Making road signs reflective is not as straightforward as it might seem. One of the main challenges is to make sure that light is reflected back towards its source. That may sound easy, but it is not. Let us explain.

Light reflects off different materials and surfaces in different ways. In general, there are three kinds of reflection: diffuse reflection, mirror reflection, and retro-reflection. Road signs are only useful at night if they are retroreflective.

Diffuse reflection occurs when light strikes a rough or granular surface, such as cloth or paper, and scatters in different directions, causing a concentrated beam of light to become diffuse or spread out. A good example of diffuse reflection is the reflection that occurs when light strikes a mat surface. The light beams hit the mat surface and bounce off it in different directions, creating a soft, unfocused reflection.

Mirror reflection occurs when light strikes a surface that is smooth or glossy, such as a mirror. Light reflects off such surfaces at equal but opposite angles and the reflected beam of light remains focused and concentrated, creating a ‘sharp’ reflection.

Here’s where we come to our first hurdle. If road signs reflected light the way mirrors reflect light, you would not be able to see them at night. When you drive past a road sign at night, the sign is usually located to the right or the left of the road.

In both situations, the light from your headlights strikes the sign at an angle. If road signs were made from regular reflective vinyl for signs materials, the light from your headlights would bounce off them at equal but opposite angles and end up illuminating the trees beside the road. Very little or no light would reach your eyes, and you would not be able to read the sign. But road signs don’t reflect light the way mirrors do. They reflect light retroreflectively.

Retroreflection is the same as mirror reflection with one major difference; light beams that strike a retroreflective surface bounce back in the same direction as they came. For the most part, retroflection is achieved in two different ways. Three mirrors arranged perpendicularly into a ‘cubes corner’ will return light directly to its source, as will a transparent sphere backed by a spherical mirror.