SDOT’s Microsurfacing Program
Last updated: August 30, 2017
What is microsurfacing?
Microsurfacing is a cost-effective method to help preserve the life of the pavement by applying a thin sealcoat; a mix of water, emulsified asphalt, and fine gravel.
This preventive maintenance process protects the pavement from cracking in the future. Check out this video of the process.
Which streets were microsurfaced?
In the summer of 2017, we microsurfaced 32 lane miles of streets in 4 Seattle neighborhoods (click on the links to see exactly which streets were treated):
How does SDOT select the streets for treatment?
In the 1950s and 1960s, the City of Seattle annexed several parts of King County. Most of these streets had a dirt or gravel surface. The City paved these streets with a minimal amount of asphalt and began a regular preventive maintenance cycle, typically chip sealing the streets on a 10-year cycle.
Because these streets are mostly low volume non-arterial streets and have received preventive maintenance in the past, they continue to be the best candidates for microsurfacing.
All the streets being microsurfaced are selected based on the age of the current pavement and an on-site inspection by SDOT staff. Streets where the pavement has degraded beyond the point where preventive maintenance is effective will be excluded, as will streets where the asphalt was recently applied.
Preparing the street for microsurfacing
It is essential that structural damage is repaired prior to the microsurfacing process. SDOT crews patch deteriorated areas of the selected roads well in advance of the microsurfacing operation.
In addition, low hanging branches and overgrowth needs to be trimmed to allow for the microsurfacing equipment to navigate the roads.
On the day of microsurfacing, crews sweep the street before applying the microsurfacing material.
What to expect the day of microsurfacing on your street
As the microsurfacing equipment moves along the street the mixture is fed into a spreader box. The material is spread across the full width of a traffic lane and then smoothed with a squeegee. The equipment also feathers the edges for a smooth transition. To complete this work, neighbors should expect:
During the month of August, we microsurfaced selected streets in several neighborhoods, shown below. Work occurred over a ten-day period from August 14 to 25.
August 14, 15
August 16, 17, 18, 19
August 19, 21, 22, 23, 24, 25
The 2017 microsurfacing project is expected to cost $970,000, and funding is provided by the REETII (Real Estate Excise Tax).
If you have questions about the 2017 Microsurfacing Program, please contact Paul Elliott, SDOT Project Communications Lead, at (206) 684-5321 or firstname.lastname@example.org.
Brian Glas, PE