Definitions of Types of Street Repair
Asphalt Resurfacing or Overlay
Asphalt Resurfacing or Overlay generally consists of the following steps:
- Grinding off selected areas of old asphalt either along the curb or within the street
- Patching any pot holes or badly deteriorated areas
- Placing a fabric (not in all cases).
- Placing and compacting hot mix asphalt pavement
- Adjusting any street hardware (manhole frames, catch basin frames) to the new grade of the asphalt and completing any restoration of adjacent properties
Resurfacing projects are usually done in groups of several individual streets and can take up to 8 to 12 weeks to complete the entire project. A contractor will generally complete steps 1 and 2 first. For example, they will do all their grinding at first, then patch; then they will place the fabric, then complete the paving next, then adjust the hardware as restoration work is being completed.
Asphalt used for resurfacing is generally placed in 2-inch thick lifts. Street resurfacing can improve driving conditions and correct improper drainage and will last generally for 8 to 10 years depending on traffic, weather conditions and the strategy of treatments.
Inconvenience with a resurfacing project is generally minimal to medium. The noise and fumes of heavy equipment are sometimes factors. Having streets in a state of workmanship for sometimes 3 to 4 weeks cause problems for both the public and the City. This can be termed 'the nature of the beast'. There is a certain amount of inconvenience that we have accepted to get the best possible value for the dollar. This is something that we take very seriously and monitor on a constant basis.
Slurry Sealing generally consists of the following steps:
- Crack sealing any selected cracks
- Patching any pot holes or deteriorated areas
- Placement of the Slurry Seal
Slurry Seal projects are usually done in groups of individual streets and can take up to 4 to 6 weeks to complete the entire project. A contractor will generally complete steps 1 and 2 first. For example, they will do all their patching and crack sealing first, then complete the slurry sealing.
Slurry Seal acts as a wearing surface and seals the existing asphalt surface, and is usually placed in a thickness of less than 1 inch and can be used on streets where the traffic volume is light, but doesn't hold up as well on the heavier traffic volume streets. Slurry Seal isn't very useful to fill in wheel ruts.
Slurry Seal is a mixture that will take several minutes to harden once placed. It is within this time frame which Slurry Seal can cause problems for the public. If it is stepped in it will track like tar until hardened. Tires will also pick it up easily. If in doubt whether it is hardened or still wet, it is best to stay off. Because Slurry Seal is placed on longer sections of roadway at once, traffic tie-ups can occur.
Reconstruction generally consists of the following steps:
- Excavating the entire roadway including asphalt and rock
- Placing and compacting rock underneath the roadway
- Placing and compacting Hot Mix Asphalt
- Completing restoration of adjacent properties
Generally a Reconstruction is performed when the street structure is deteriorated to the point of no return. For a typical local street, rock will be placed first and then asphalt will be placed. In some cases, the rock may be eliminated and the asphalt increased. For streets with a higher traffic volume, both the rock and the asphalt thickness may be increased. The decision as to which type of street to build is done at the design stage. A Reconstruction will generally last for 20 to 25 years depending on traffic, weather conditions and the proper strategy of treatments.
Reconstruction projects, in some cases, will have underground conduit, sewer pipe or water main installed prior to the street reconstruction. This requires coordination with the other utilities such as PG&E, EBMUD, and AT&T and can significantly increase the length of time for the project to be completed.
The amount of inconvenience for a project of this type is usually the greatest among the different street treatments. Generally access to property is maintained, but inevitably, when concrete is poured or asphalt is placed, complete access is limited. Dust and the noise of heavy equipment are other factors. These inconveniences are usually outweighed by the increased level of service to the public with a safer roadway, decreased maintenance costs for the public and the City, as well as the aesthetics of a new street.