HONOLULU (HawaiiNewsNow) - Drivers know that Oahu seems to be a paradise for potholes.
City crews are always busy patching and repaving failing roads, but they also run into unexpected challenges. They typically tackle anywhere from 700 to 2,500 potholes a week. Workers use a "throw and go" method, filling the hole with asphalt and packing it down before moving to the next pothole.
The city Department of Facility Maintenance has a $2 million budget for asphalt concrete used in pothole patching and emergency overlays. Officials acknowledge that heavy rains usually wash the temporary patches away.
"Our methods are not intended to provide a permanent repair for the roads, but actually to provide a means of filling potholes so that we can reduce the amount of hazards that are out there," said DFM director Ross Sasamura.
Grace Pacific sells the city the hot asphalt mix. The company's plant at Campbell Industrial Park can produce 400 tons per hour.
"Hot mix asphalt is mainly made up of 95 percent aggregate and 5 percent liquid asphalt. Of course, aggregate is rock, and we blend it to meet the different city and state specifications," said Scott Komatsu, Grace Pacific Corporation's hot mix asphalt plant manager.
Sasamura added, "There are different types of modified asphalt mixes that improve durability, but with that comes cost so it's always a matter of balancing value for the product that we pay for."
The best way to prevent potholes, though, is to maintain the whole road.
The mayor wants 1,500 lane-miles of city streets repaved by 2018. Some 900 of the 975 lane-miles already completed were "mill and fill," in which workers just replace two to four inches of the top asphalt. Even simple projects can quickly become complex. Crews discovered extensive damage to deeper layers once they dug up La'i Road in Palolo.
"In this area where there is heavy rains, a lot of rain seepage, it's a lot more of a problem," said Robert Kroning, director of the city Department of Design and Construction.
Some full-depth reconstruction projects ,such as the ones on Kapahulu Avenue and Beretania Street, have had to be scaled back due to shallow utility lines.
"Over the years, we haven't done a good job of maintaining records of depths of utilities and so we've been running into them when we don't expect to," Kroning said.