Why is it Important?

Almost one-half of all traffic fatalities occur during the dark hours of evening, night, and early morning.
However, only one-fourth of all travel takes place during those same hours—a startling and grave statistic.

On a dark and unlit road, nearly all visual cues disappear except those that are retroreflective (signs and markings). Those few remaining cues become critical to driving, and should they become so worn that they are no longer easily visible, the chance to miss the information becomes greater, resulting in a greater chance of driver error, and subsequently, a potential crash. Urban areas present a different environment related to retroreflectivity of signs. Other light sources, such as advertising signs and business lighting, create a situation where the traffic signs are competing for the driver's attention. In many of these situations, the retroreflectivity of traffic signs must be even greater to stand out among the competing lights.

When driving roads at night, retroreflective materials may be traffic signs or pavement markings and the source the light is usually the headlights of a vehicle. Because a driver's eyes are close to a vehicle's headlights, some of the light returned from retroreflective materials reaches the driver's eyes. The amount of light from an object reaching the driver's eyes will have a great impact on how bright that object appears to the driver. Therefore, retroreflective materials that are efficient in returning light to a driver's eyes may appear brighter to the driver than those that are not.

Unfortunately, the retroreflective characteristics of traffic signs and pavement markings deteriorate over time. As a result, it is important to replace these assets prior to the time when they no longer meet the needs of nighttime drivers. The major question is not whether the devices should be replaced, but when? How do we know when the device no longer meets the needs of the driver? 

The bottom line... municipalities should actively manage the maintenance of signs and pavement markings in order to ensure that they are clearly visible at night.  The routine inspection of the retroreflectivity of road signs and pavement markings should be a part of a municipality's asset management or road safety programs . 

Rules and Regulation

Legislation in ONTARIO
Since 2010, the Minimum Maintenance Standards for Municipal Highways (O.Reg 239/02 of the Municipal Act) requires that all regulatory and warning signs must be inspected on an annual basis to ensure they meet the retroreflectivity requirements of the Ontario Traffic Manual (OTM).  The Ministry of Transportation officials have recently updated Book 4 of the OTM and now include minimum levels of retro-reflectivity which provides a clear direction and finally bridges the disconnect between he MMS and the OTM. The OTM has adopted the Minimum Levels of Sign Retro-reflectivity that were previously released by the Transportation Association of Canada’s in their revised Manual of Uniform Traffic Control Devices for Canada (MUTCDC).