Preserving Bothell's pavement

Annual Arterial Overlay Program

Asphalt pavement deteriorates over time:

  • Tiny cracks appear on the surface.
  • Light rutting appears in the wheel paths and cracks grow larger.
  • The roadway doesn’t drive as well.
  • Rainwater doesn’t shed as freely.
  • Water seeps into cracks and erodes the gravel supporting the asphalt.
  • Potholes appear, and driving is rough. 

At this stage, only extensive and expensive repaving can repair the roadway. The annual budget varies depending on grants awarded. The target annual investment for this program is $3 million.

Where does the money come from?

Revenue Source Estimated Annual Revenue

Taxes & Fees

​(REET, solid waste fee, street cut fee)

Safe Streets & Sidewalks Levy


Estimated Grants


Total Annual Revenue:


What does this work include?

Bothell conducts field surveys every year. Typically, half of the City is evaluated each year. We measure the size and type of cracking, the surface condition (weathering and raveling), ruts, and patching. Based on the survey data, the roadways are assigned a Pavement Condition Index (PCI). This information drives the annual projects.
Preventive treatments are substantially less expensive than repaving, so more roads can be treated each year for the same cost. Preventive treatments, applied at the right time, extend pavement life by preventing rainwater from seeping into and undermining the pavement. This work is done in partnership with in-house asphalt patching projects.

That target annual program includes:

Program Element Proposed Annual Expenditure

Arterial overlay


Arterial seals


Local seals




Total Annual Cost:


Pavement Condition Index (PCI) Ratings

85 - 100Excellent61%
70 - 85Very Good
55 - 70Good29%
40 - 55Fair10%
25 - 40Poor
10 - 25Very Poor
0 - 10Failed0%

Each street’s PCI rating is entered into asset management software that predicts the roadway’s future condition, based on historical PCI data, pavement preservation techniques, and spending levels. Based on the PCI, roadway classification, budget, and other factors, staff determines which streets will be paved each year.

Pavement preservation techniques: Added pavement life expectancy by roadway condition

Treatment Comparative Cost Very Good Good Poor
Slurry Seal Low 7 - 10 years 3 - 5 years 1 - 3 years
Chip Seal Low 7 - 10 years 3 - 5 years 1 - 3 years
Microsurfacing Moderate 8 - 12 years 5 - 7 years 2 - 4 years
Overlay High 10 - 12 years 5 - 7 years 2 - 40 years
Reconstruction Highest 15 - 20 years 15 - 20 years 15 - 20 years

Cost of deferred maintenance

Pavement Condition Index 2017 (JPG)