Improper installation causes parkway concerns
November 1, 2012
By Christina Corrales-Toy
Phase one shows indications of ‘premature failure’
A portion of Coal Creek Parkway between Newcastle Way and Southeast 84th Way is showing signs of “premature failure,” with indications of longitudinal cracking, according to Bryan Hawkins, an engineer with HWA GeoSciences Inc.
The city of Newcastle contracted with the company to study pavement conditions on phase one of Coal Creek Parkway.
The report states that there was likely no tack coat applied between the upper and lower lifts of pavement that were installed in 2002 and 2003.
The lack of a bond between the two lifts is not ideal because it creates air pockets, Public Works Director Mark Rigos said.
“Air pockets are bad in pavement because it can result in water infiltrating through the pavement in the cracks, and then when you have freeze-thaw conditions, it can expand the pavement and rupture it and cause cracking, and that’s a problem,” he said.
But the absence of a tack coat was not the only reason the road may be deteriorating faster than anticipated, Rigos said. Heavy truck traffic from the construction of phases two and three of Coal Creek Parkway, increased development in the Renton Highlands and heavy snow-plow usage may have contributed as well.
A road that gets as much traffic as Coal Creek Parkway is expected to last about 20 years, Rigos said, but some sort of reconstruction will need to be done before 2015.
The reconstruction and repair of the road requires the removal of the upper and lower lifts of asphalt, which amounts to about 6 to 7 inches of pavement, on that portion of Coal Creek Parkway. Then, two brand new lifts will need to be installed, Rigos said.
“If reconstruction happens in 2013, great, if it happens in 2014, that’s fine, too. We can crack seal it next year, but I don’t think we can push it off much beyond that without just having lots of potholes out there,” he said.
The city hopes to get at least a portion of the project funded with grants, City Manager Rob Wyman said. The project is estimated to cost $800,000, but the engineer said that could increase the longer the city waits to work on it.
The city has applied for a $400,000 grant to help pay for the project. If the city gets the grant, Wyman said work on the reconstruction can begin in 2013, with the other half paid for out of the $683,000 that the city budgets for pavement overlay.
If the city does not get the grant, Wyman said the city will wait, apply for the grant again next year and crack seal the road this year. Crack sealing will temporarily extend the life of the pavement.
“It’s a road that gets a lot of traffic, a lot of buses and at the end of the day, it hasn’t been a disaster,” Rigos said. “It’s not like it lasted three or four years and went bad. Does it get an A+? No. But maybe it gets a passing grade.”