Reflective Traffic Signs
High Intensity Signs
Placement for retroreflective signs may vary depending on whether they're roadside or overhead, and depending on rural or urban setting, you may need higher levels of reflectivity than the minimum.
Optimum placement of reflective traffic signs
Retroreflective signs are illuminated for the human eye when the entrance angle..

Read More
The science behind reflective traffic signs
What are reflective traffic signs and what is their importance? Elaborate on how these

Read More

Optimal placement of reflective traffic signs

Regardless of what kind of sign you install, the placement will affect the sign’s visibility, and ultimately, the sign’s effectiveness. This is especially true for retroreflective traffic signs, because their effectiveness is reliant on illumination from the car’s headlamps. Because of the orientation of those headlamps, a low beam will create different levels of luminescent depending on whether your sign is on the right or left side of the road, or overhead.

How should reflective traffic signs be placed on the road so that they are clearly visible to drivers?

The positioning of signs on the roadside requires knowledge of standard requirements with critical offsets positioned along the road, laterally from the edge of the road, and vertically above the ground.

These designations will vary depending on where the sign is being installed: residential or business district, roadside rural district, or warning sign. You also have to consider positioning signs to avoid mirror glare, differences in day and nighttime visibility, and proper alignment of a cluster of signs.For instance, studies have shown (like this one from the Texas Transportation Institute that studied conditions for reflectivity) that the farther from the road a sign needs to be posted, the higher-grade visibility the reflective material should be, even above the minimum reflectivity.

Rural settings

Rural roads are considered among the most dangerous roads, accounting for about 60% of all fatal crashes. While less than one-third (28%) of all vehicle mile travel occurs on rural, non-interstate roads, more than one-half (52%) of all fatalities occur there. For every 100 vehicle miles traveled, fatalities are 2.75 times higher on rural roads than on other roads.

One of the problems encountered in rural setting is the difficulty of establishing contrast against an often changing natural and often obstructive background, especially vegetation.A study by the FHWA concludes, "One potential hazard is vegetation. Trees close to the road can present a fixed object hazard. Grass, weeds, brush and tree limbs can obscure or limit a driver's view of traffic control devices, approaching vehicles, wildlife and livestock, and pedestrians and bicycles. Controlling vegetation helps reduce crashes and injuries."

Urban settings

High-intensity grade retroreflective materials are recommended for urban settings because cities, although functionally very different from rural areas, also require signs withhigher visibility for different reasons: there is a greater level of ambient light in urban environments at night, as there is during daylight hours, which obscures or diminishes the visibility of signs.

There are several key differences between rural and urban environments: for one, urban environments have more intersections per mile, increased ambient lighting, higher traffic volumes, more frequent signalization, and lower speeds. All of these factors mean the urban environment is more visually complex, and increased visual complexity can impact sign legibility and eye-glance behavior.

Overhead signs

Overhead signs have the least retroreflectivity, but they allow for vertical and lateral clearances as established by municipal agencies. Types I, II, and III beaded sheeting cannot be used for the white legends on overhead guide signs but rather a prismatic lens type should be used.

Although Types I-III are not recommended for overhead signs, the FHWA declined in 1998 to establish minimum retroreflective levels for non-illuminated overhead signs.Referencing the new standards, the FHWA currently states, "The minimum retroreflectivity levels in Table 2A-3 in the MUTCD prohibit the use of less efficient reflective materials for overhead signs so that agencies do not use them. As a result, agencies are more likely to select appropriate materials to meet nighttime driving requirements."

Home | The science behind reflective traffic signs | How do reflective traffic signs contribute to safety? | Optimal placement of reflective traffic signs
Federal Highway Administration|Reflective sheeting – which is the best?|Sitemap | Contact us

© Copyright 2012 | All rights reserved.