Portland’s Bureau of Transportation (PBOT) employs a number of different treatments to repair and maintain street pavement. The type of road often determines the type of treatment.
Arterials and collectors, with their frequent and heavy loads, experience harsher wear and tear. This deterioration often reaches below the road surface and affects the street’s base structure. The weight of a standard passenger bus, for example, has as much impact on the pavement as ten thousand automobile trips. Correcting damage to the base structure of the road is more complicated and expensive than addressing surface-level problems like cracks and worn asphalt.
Neighborhood streets, on the other hand, experience far less traffic and often can be maintained and repaired with less costly methods.
Common Types of Pavement Treatments:
Pavement cracks are sealed to prevent water and debris from entering a crack and penetrating into the base and subgrade material of the road.
To extend the life of a street, crews will first clean the pavement and then apply fog seal - a mix of asphalt, fine grit and recycled rubber tires that is sprayed onto the street, forming a durable protective seal. Find out answers to frequently asked questions about fog sealing on your street.
Grind and pave:
If there are no noticeable base or subgrade failures but the existing surface exhibits extensive cracking, roughness or rutting, the top layer of a road are ground down and replaced. Often this work will be done in two phases since grinding can be done in almost any weather while paving requires a dry day.
Grind and pave more than two inches:
Over two inches of the road are ground down and replaced. This treatment is commonly referred to in budgets as “contract paving,” since according to Oregon State law, this work must be performed by contractors under city supervision and not directly by city crews.
When a section of a street has deep damage in isolated areas, crews will remove and replace both the base and the surface layers. Like filling a pothole, this work only corrects a section of the street, although base repair is a deeper treatment than pothole filling and the repair is more durable.
The construction of a new pavement structure, which usually involves complete removal and replacement of the existing pavement surface and base followed by new construction of the street. This often entails replacing stormwater drainage facilities adding ADA improvements, utilities under the roadway surface, and other infrastructure in the right of way.
See here for more information on the associated costs for repairing arterials and collectors.