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.
Street maintenance is heavily weather dependent. Although crews work year round, the most productive months are from June to September.
Common Types of Pavement Treatments
Fog and Crack Sealing:
This treatment is performed on residential streets in generally good condition. First, crews seal the visible cracks on the streets. they will follow this up with a fog seal that seals the road surface from the effects of water and the sun. Fog seal is a liquid petroleum product consisting of water, asphalt, recycled tires and grit and is sprayed on clean pavement and allowed to dry. It protects the roadway from weatherization for an estimated 3-5 years. It costs $10,000 to $12,500 per mile.
Find out answers to frequently asked questions about fog sealing on your street.
Grind and pave:
This treatment is used for high-traffic streets which are typically in fair condition with little or no evidence of failure in the road base. The top two inches are asphalt are ground down, recycled and the road is repaved. This treatment typically costs $150,000 per mile.
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.
This treatment is reserved for streets that are in poor or very poor condition. The work is limited to small areas within a street that is falling apart and/or a potential hazard to road users. Both the rock base and the asphalt street surface are removed and completely replaced. Base repair is very expensive and typically costs $500,000 per mile. Although this type of repair is expensive and only limited to small areas of a failing street, it allows PBOT to address urgent safety needs and improve the street’s condition.
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.