Most cities prefer asphalt because it cures quickly, allowing new roads to open for traffic sooner. And it’s easier to repair. But concrete has its advantages, too.
Ask some residents of Edina’s Tingdale Avenue about their street, and this is what you hear: It has a tough, environmentally safe surface; residents can walk on it barefoot at the height of summer without searing their feet, and kids claim that when they fall from their bikes they are less likely to get “road rash.”
Their street is concrete, soon to be replaced by asphalt. That doesn’t make sense to homeowners like Judd Rietkerk.
“I think the concrete that is out here now will last longer than the new asphalt,” he said. Concrete, he said, “just goes on and on.”
The concrete vs. asphalt debate is an old one, and a hot enough topic that it draws a sigh from traffic engineers who are asked which is better. “Better” depends on the site, the soils and the budget.
Yet people who have concrete streets often like them. When the Edina City Council began preparing to redo roads and underground utilities in the Birchcrest neighborhood, where about 30 percent of streets are concrete, residents sent e-mails and showed up in person to praise concrete.
In April, the council decided to replace all of Birchcrest’s concrete streets with asphalt. Chad Millner, Edina’s director of engineering, said one of his goals this year is to develop a plan for dealing with Edina’s concrete streets, which are 50 to 60 years old.
“We lean toward removing them and putting blacktop in,” he said.
Concrete was popular decades ago when asphalt technology was in its infancy, said Curt Turgeon, the Minnesota Department of Transportation’s state pavement engineer. Minnesota’s early paved highways were concrete.
“We knew how to build concrete streets then; the technology hadn’t evolved much with asphalt at that time,” he said. “Now plants pump out asphalt quickly and you can lay it and drive on it.”
In Edina, an estimated 30 percent of residential streets are concrete; in Minneapolis that proportion is 25 percent. Bloomington has none. In Richfield, the only concrete city street — that is, not a state or county road — is 77th Street.
Until recently, concrete was more expensive than asphalt, but rising oil prices have shrunk the price difference. Turgeon said he wasn’t sure what the proportion of concrete streets is in Minnesota, but said choice of street materials is dictated not only by price but by soil conditions. Concrete is more commonly used in northwestern Minnesota, he said, where soils are unstable and concrete provides the needed rigidity to bear traffic loads. Concrete also is used where gravel, a base for asphalt roads, is scarce.
Cities prefer asphalt because it cures quickly, allowing new roads to open for traffic sooner. And it’s easier to repair.
Streets from the ’60s
But concrete has its advantages, too.
Rietkerk, a former Minneapolis city employee who knows a bit about street work, cited concrete’s durability when he was making his case to the Edina City Council.
“Asphalt has the maintenance factor,” he said. “In five years you have to seal-coat it, and you do it again at 10 years and 15 years, and then it needs a mill and overlay. And when you patch asphalt, it settles different, and you always have a bump. Look at the potholes.”
Mike Kennedy, Minneapolis’ director of transportation maintenance and repair, said concrete is indeed durable — for a time. The oldest of the city’s 150 miles of concrete residential streets date back to the mid-1960s.
“It’s pretty remarkable, what shape most of them are in,” Kennedy said. “They last a long time. ... But when they go, they go fast. We have some that are in very rough shape.”
Minneapolis doesn’t build concrete streets anymore, and it is checking out the latest in concrete renovation to figure out how to extend the life of the ones it has, Kennedy said. It has patched some concrete streets with asphalt — a technique Edina rejected because of the black-and-white “Swiss cheese” appearance — but repairs holes made for utility repairs with concrete.
Concrete has some cracks
For cities, the biggest headache with concrete is that when concrete ages, panels shift and joints need to be repaired. Richfield has county roads that were originally concrete and were overlaid with blacktop, but the concrete base is so deteriorated that “the cracks just shoot to the surface,” said Jeff Pearson, city transportation engineer.
In the next few years, Hennepin County will join with Richfield to replace concrete-based arterial streets like Portland Avenue and 66th Street with new asphalt, a decision Pearson favors.
“For a local street, I’d be hard-pressed to find a use for concrete over asphalt,” he said.
Edina’s Millner agrees. If the concrete streets in Birchcrest were just 30 percent damaged, the city might have repaired them, he said. But about half of the panels in those streets either need repair or will be damaged by major utility work that will be done this summer.
Millner said if those concrete streets were replaced with concrete, residents could not drive on them for a week and the surface would not reach its full strength for almost a month. And residents would be paying about $3,000 more per household to replace their streets.
Rietkerk acknowledges that concrete is not perfect. In some places, his street is cracked and concrete is crumbled around manhole covers.
“Sure, you get chucks, bump, bump, bump,” he said. “We put in speed bumps to slow traffic. It’s the same effect.”
He says he didn’t lose the debate over what to do with Tingdale. He’s getting a nice, smooth, new blacktop street.
“I think the city lost,” he said. “Because they will have to maintain it and they will lose it sooner.”
Mary Jane Smetanka • 612-673-7380