The City of Prince George spends millions of dollars per year maintaining its extensive road and sidewalk network. The City's Roads Division presents Council with an annual list of projects that can be completed according to the road and sidewalk rehabilitation budget approved by Council.
The City uses a variety of equipment to repair holes that emerge in the road surface. These potholes can become common in the late winter and spring because of freeze-thaw cycles.
The City produces an interactive map every year showing the location of road and sidewalk rehabilitation projects being undertaken that year.
This method involves applying a modified cold mix pavement made up of dense graded aggregate, asphalt emulsion, water, and mineral fillers. It is applied in a thin layer and therefore does not add structural strength to the roadway. This method can only be used on asphalt that is in fairly good condition with low traffic volumes and is intended to prolong the life of the underlying asphalt surface.
Thin Life Overlay
The majority of the City's rehabilitation program consists of the placement of a 40mm – 50mm layer of asphalt over existing asphalt with limited remedial work done prior to the new layer being placed. This overlay does add structural strength to the roadway, but reflective cracking will eventually appear. This method is used in situations where the existing roadway has good structure and only minor surface deficiencies.
Mill and Overlay
This method removes 50mm of existing asphalt, which is then replaced with new asphalt. This method allows for the replacement of asphalt without increasing the a roadway's elevation.
Milling removes surface deficiencies and is used predominantly in urban situations where curb and gutter are present and road elevation is critical for drainage considerations. The milled material is used to surface gravel roads throughout the City.
A variation of this method involves the milling of the area adjacent to the curb and gutter, but not milling the asphalt from the majority of the roadway. This allows for the overlay to meet the curb elevation, but does not incur the cost of a full milling operation.
Pulverise and Pave
In this process, the existing asphalt and granular base is pulverised in a similar way to milling. However, with this method the pulverised product is then graded and reshaped, a 50mm lift of crush is added, and a 75mm layer of asphalt is placed. This method is used where the existing road surface has major deficiencies. This method is considerably less expensive than a complete reconstruction of the roadway but is not desirable for roadways with underground utilities.
In some cases, the gravel base beneath an existing sidewalk is suitable. If so, the existing hard surface of the sidewalk is removed along with enough soil to allow the placement of 80mm crushed gravel and 100mm thick concrete sidewalk.
In other cases, a full reconstruction is necessary. This involves removing the existing sidewalk surface and unsuitable soils to a depth of nearly one metre to allow the placement of gravel followed by a 100mm-thick concrete sidewalk.
Gravel Road Maintenance
Various types of maintenance treatments are used on gravel roads and treatments include:
Recycled Asphalt Pavement ‐ Millings (RAP)
Millings from the Road Rehabilitation program are placed on gravel roads. These millings are placed, shaped, and compacted in 200mm to 300mm layers. Placing millings on gravel roads provides a harder surface that needs less grading maintenance and reduces the amount of dust produced by traffic considerably.
19mm Minus Crushed Gravel
Crushed gravel are used on existing gravel roads that have a good sub base and require minor surface maintenance. Crushed gravel are placed, shaped, and compacted to restore a smooth driving surface.