Well, the road surface material, asphalt, is a black petroleum-like material that has a consistency varying from thick liquid to glassy solid. It is obtained either as a residue from the distillation of petroleum or from natural deposits. Asphalt pavement is a multi-layered structure. The bottom layer can be soil, called sub grade; if the soil provides adequate support to serve as a sub-base, it can be compacted crushed stone and gravel.

 

The layers above the sub base are compacted aggregate particles coated with asphalt. Each of these layers is coated to bond to the layers above and below. Each layer of asphalt aggregate mix, while hot, is rolled over the layer beneath and compacted. The top layer is sealed. Asphalt pavement is flexible (unlike concrete) and is ideal for colder temperature zones where constant freezing and thawing occur. But it does have some shortcomings.

 

Constant freezing and thawing combined with wear and tear from traffic will eventually degrade the pavement, causing cracks. During thawing, water seeps into the pavement structure through these cracks. As the temperatures cool to freezing at night, the water becomes ice and expands, forcing the pavement to rise. A shallow divot forms under the surface and the pavement breaks, forming a pothole. Potholes are defined as “bowl-shaped openings in the pavement resulting from localized disintegration.”

 

Since, by all measures, winter 06/07 has been and continues to be a tough winter, not surprisingly, potholes are springing up all over.

 

Any driver who has struck a pothole knows that we are discussing a serious road hazard. Driving over even a shallow pothole at full speed may damage tires, rims, suspension, and wheel alignment. It may cause loss of control of the vehicle either by causing loss of traction or steering control.  Instinctively, most drivers try to avoid potholes altogether by driving around them—sometimes called “swerving.” If they cannot avoid them, they may brake suddenly to attempt to minimize the effect of hitting one. Both reactions can cause serious problems for nearby vehicles.

 

Pothole repair is simple. Asphalt patches well. Maintenance mixes of asphalt emulsion and mineral aggregate can be applied over small areas to patch holes, depressions and distressed areas. But, right now, as fast as the municipalities and provincial government are making these repairs, new potholes are appearing. If you see what you think is a new pothole, reporting it will be helpful. Go to www.th.gov.bc.ca/popular-topics/maps/serviceareamap.htm for the telephone number of the road and bridge maintenance contractor in your area.

 

Safe driving on winter roads involves application of the three-second rule, that is, maintain a three second following distance. You need sufficient time to avoid harm if the driver you are following encounters a pothole and reacts instinctively. You need sufficient time yourself to see the pothole hazard and to safely avoid or minimize its impact.