Road pavement condition is assessed every 2-3 years. In order to assess pavement condition, inspections and distress surveys are conducted for each street segment, each of which can include up to several blocks. Types of distress include alligator cracking, longitudinal and block cracking, weathering, raveling, and patches.
In 2016, the Metropolitan Transportation Commission rated the overall condition of San Mateo roads as “Very Good” with a PCI of 76.
Pavement Condition Index (PCI)
During street surveys, a Pavement Condition Index (PCI) is calculated for each street segment. Ranging between 0 and 100, a PCI of 100 would correspond to a pavement at the beginning of its life cycle. A PCI of 0 would correspond to a badly deteriorated pavement with virtually no remaining life.
PCI Range: 90-100 Condition: Excellent Description: Little or no distress as a result of being recently repaved or rehabilitated.
PCI Range: 70-89 Condition: Very Good Description: Some utility patches in good condition, or minor to moderate hairline cracks; typically lightly weathered. A road with this score is eligible for crack sealing and slurry seal, which is the first defense against water penetration. Slurry seal is a surface treatment that involves the application of a thin layer of oil and sand to prevent water penetration and can be applied in 3 to 5 year intervals.
PCI Range: 50-69 Condition: Fair/Good Description: Light to moderate weathering, light load-related base failure, moderate linear cracking. A road with this score is eligible for an overlay. Overlay involves removing 1-2 inches of asphalt and putting down new asphalt of the same thickness. This treatment can last 8-12 years. This process is considered preventative maintenance that will help delay street deterioration.
PCI Range: 30-49 Condition: At-Risk Description: Moderate to severe weathering, light to moderate levels of base failure, moderate to heavy linear cracking. A road with this score is eligible for a “medium to thick” (2-4 inches) overlay, which is a cost-effective alternative to full reconstruction. We remove the old asphalt and apply a new asphalt layer but do not replace the base layer. This treatment provides a new wearing surface and typically extends the life of the street for 10-20 years.
PCI Range: Under 30 Condition: Poor Description: Extensive weathering, moderate to heavy base failure, failed patches, extensive network of moderate to heavy linear cracking. A road with this score is required to be reconstructed, which involves the removal and replacement of pavement and base. This process is the most expensive and is the last approach taken to improve a roadway.