Better Roads Staff
The city began using full-depth reclamation (FDR) in the reconstruction of selected streets in 2009. “We have poor soils here, so we use FDR with a portland cement additive to create a strong platform,” explains Klope. “We started with three local streets and it went so well that we added more local streets and an arterial last year. Because of local soil conditions, Klope says the city’s FDR process digs deeper into the soil than typical reclamation practices and can use a much higher mix of portland cement — up to 8 percent.
Eugene is also testing whitetopping as a solution for an intersection that has a high volume of heavy trucks. The city milled 6 inches of the old asphalt pavement and placed 6 inches of concrete on top of it. It is the city’s first use of whitetopping on a street, though the technology has commonly been used for bike paths in Eugene.
Eugene is also making a major commitment to warm-mix asphalt, using it for almost all of its paving projects since 2009 – a total of more than 120,000 tons so far. The city adopted warm mix for environmental reasons and in hopes of some slight gain in lifecycle cost efficiency. “We like the higher-effect asphalt content,” says Klope, “and we hope that translates into longer life. Meanwhile, it meets our community’s environmental goals and it’s good for workers.”
Klope says Eugene contractors have found warm mix a little easier and faster to compact than hot mix, but they don’t like raking it; therefore, small, irregular areas are often done with hot mix.
Life Goes On
While the specter of inadequate budgets hangs over many state and local road agencies today, most road agencies are trying to maintain current levels of pavement and bridge condition until the economy recovers and budgets return to normal levels.
“Metro government has put a lot of its efforts into maintenance activities, with potholing, overlays and crack sealing to extend our pavement life with more cost-effective measures,” says Jeremy Raney, executive administrator in the Louisville, Ky., Department of Public Works and Assets. “Most of our efforts are currently focused on maintenance of existing structures and replacing those that have more severe deterioration.”
Like many other road departments, Louisville was able to use Stimulus funds for critical upgrades, but now faces a much tighter budget and more limited capabilities.
Still, says Raney, Louisville is using its asset management system to establish priorities for bridge and pavement rehabilitation, and the city’s maintenance department is focused on critical preservation activities, including replacement of deteriorated cross drains and shoulder repairs.
Ironically, our conversation with Raney was delayed and truncated by severe weather and flooding in the Louisville area last spring, a reminder to us all in this period of taut budgets and growing needs that all strategies and tactics are subject to the whims of natural events.
Working a Watershed in Winter
Recession or not, the environment needs help
Even in the dark shadows of the Great Recession, the need to develop road designs with sounder environmental attributes is a driving force in many areas.
In the Twin Cities suburb of Robbinsdale, a partnership of road and watershed management agencies is working with the Minnesota Asphalt Pavement Association and the consulting firm of Wenck Associates on a three-year study to see if the use of porous asphalt can reduce the need for road salt in an environmentally sensitive watershed area.
The Shingle Creek Paired Intersection Project was launched in 2009 with a $282,000 research grant and the construction of 150-foot test sections of porous asphalt and conventional asphalt on a Robbinsdale residential street with a sandy subgrade. A second test site was built in 2010 on a clay/loam subgrade.
“We will monitor these sections for three years,” says Ed Matthiesen, a consultant with Wenck Associates. “We want to estimate the effectiveness of porous asphalt in reducing the need for salt as a de-icer and determine whether porous asphalt can stand up to the rigors of residential street use.” In addition, the study will determine short-term maintenance requirements and project long-term requirements, and the team will measure the water quality and quantity performance of porous asphalt.
Though the study won’t be completed until 2013, the intermediate results have been promising. “The control sections with salt tend to melt faster than the unsalted porous asphalt sections, but there is less refreezing of melted snow and ice on the porous pavement,” says Matthiesen. “And it appears to work just as well as salted pavement at clearing ice buildup.”
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