It’s ba-a-a-ck. After a six-year absence, that crunchy road surface known as chip seal has returned as the resurfacing method of choice for some older residential Overland Park streets. With chip seal, contractors lay down a film of oil followed by a layer of fine gravel that is pressed in with a heavy roller. The loose gravel is then swept away, says Wayne Gudenkauf, supervising civil engineer with the city public works department. Resurfacing can extend the life of a street by about seven years before it has to be completely repaved.
Chip seal fell out of favor in 2005, when some residents objected to the mess created by loose rock and oil. The city stopped using it on residential streets in 2006, but it has continued on some commercial streets, said Public Works Director Doug Brown.
Instead, the city has used microsurfacing, in which a black slurry of rock, asphalt and filler is laid down over the street.
Chip seal is only slightly less expensive than microsurfacing, but there are other reasons for bringing it back, public works officials said. For one thing, there is only one contractor available to do microsurfacing, Brown said.
Also, chip seal is a better option because of the way it bonds with existing pavement, said Gudenkauf. Older pavement needs the more flexible bond created by chip seal. That is why the city is using it on streets 30 years old or older. The average lifespan of a street is about 50 years before it must be replaced down to the subsurface.
“Chip sealed streets tend to perform better on older streets. It’s a more effective way of preserving them,” Brown said.
And there have been improvements in how chip seal is done, he said. Road resurfacers now use a smaller rock than they did seven years ago, which makes for a smoother surface. In addition, the loose rock — a major complaint from chip seal opponents — is swept multiple times.
As for eye appeal, Brown said it evens out over time, between chip seal and microsurface. “Chip seal is not going to change much in appearance,” he said. But with microsurface, “the eye appeal dissipates a lot quicker than with chip seal.”
The city chip sealed just over 90 lane miles this summer, which is about equal to the amount of microsurface it used, Brown said. (A lane mile equals one half the width of the typical residential street.)
Brown said he has not heard complaints about the chip seal, which has been mostly in the northern part of town. “Most of them understand that it has nothing to do with the geography of the city. It’s just that the north part has a lot of streets that are older,” he said.
As the city ages, chip seal will move south and the northern part will have more rebuilt streets, he said.