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.
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.
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.
Crushed gravel is used on existing gravel roads that have a good sub-base and require minor surface maintenance. Crushed gravel is placed, shaped, and compacted to restore a smooth driving surface.