Why do you spread all that tar and gravel on the paved roads?
The process you are referring to is sealcoating. It is a relatively low cost method of preserving existing low-volume pavements. This “seal” prevents water from freezing in the cracks and breaking up the pavement. A sealcoat offers the best protection for the least amount of money, and makes a road last longer. The tar is actually an emulsion of water and liquid asphalt which penetrates and seals small cracks in the existing pavement. Sealing these cracks on a regular basis prevents water from seeping into and softening the base of the road and over time causing potholes to form. The pea stone that we use for cover material sticks to the emulsion and, after rolling and sweeping, provides a slightly roughened skid resistant surface to improve safety. Although sealcoating can preserve and extend the life of the pavement, it is only a surface treatment and does not fill any existing bumps, holes, or irregularities and thus does not improve the ride quality. For this reason it is important to apply sealcoat to a road BEFORE this deterioration occurs, which leads us to sealcoat roads that are in generally good condition rather than waiting for them to deteriorate to the point that extensive patching is necessary.
There is a downside, however, as vehicles travel over the new surface small rocks may come loose under the tires. When a motorist encounters a newly chip sealed road, which will be marked with “Loose Gravel” signs, the best preventative is to reduce the vehicle speed and keep plenty of distance from any vehicle in front of them.
What are “All Season” roads?
So called “All Season” roads are those that have been designed and built with additional strength and durability to withstand truck traffic loads all year long, and thus they are not subject to the reduced loading restrictions that are placed on most roads during the early spring in Michigan. Roads not constructed to “All Season” standards are subject to a reduction in allowable loading and speeds during the period each spring when thawing of the ground below the roadbed softens the roadbed and makes the surface susceptible to damage from heavy loads.
What are seasonal weight restrictions?
Seasonal weight restrictions are legal limits placed on the loads trucks may carry. During late winter and early spring, when seasonal thawing occurs, the maximum allowable axle load and speed is reduced to prevent weather-related breakup of roads.
Courtesy of the County Road Association of Michigan. www.micountyroads.org