Farm Horizons, October 2013
Roads turning white as concrete prices become more competitive
By Ivan Raconteur
Only about 27 miles, or just under 11 percent of the nearly 255 miles of county state aid highways in McLeod County are concrete, or “white” roads, as engineers call them, but the percentage of concrete roads is increasing.
Currently, CSAH 2 east of Silver Lake represents the most miles of concrete among McLeod County roads, at just under 11 miles.
McLeod County was the site of the most concrete road projects among Minnesota Counties for the period 2005-2012 with 11 projects.
Olmstead County in southeastern Minnesota was next, with five projects. Anoka County was third with four projects; Freeborn and Steel counties each had three; 10 counties did two projects each, and 13 counties completed one project each. Most of the projects are located in the southern half of the state.
Comparing counties based on total miles of county state aid roads with concrete pavement, most counties have 5 percent or less concrete pavement.
McLeod, Hennepin, and Ramsey counties are in the 5 to 20 percent range, and only Olmstead and Waseca counties have more than 20 percent of their county state aid highways paved with concrete.
The biggest reason for the increased popularity of concrete roads is price, according to McLeod County Engineer John Brunkhorst.
Historically, the cost of concrete and bituminous road surfaces have been similar. However, since about 2005, the cost of concrete roads has risen less than the cost of bituminous roads, due in part to fluctuations in the cost of oil.
As a result, concrete-surfaced roads have become much more competitive.
According to Brunkhorst, factors in the type of road surface include cost, longevity, existing structure, and road width.
Brunkhorst said he looks at the total cost of the product when determining what type of road surface to use.
Although the initial cost of bituminous paving may be lower, the total life cycle cost of concrete paving is significantly lower.
Brunkhorst provided an engineer’s estimate he used for CSAH 2 in Silver Lake showing the initial cost of base and surfacing for bituminous paving is $477,760, which is less than the $528,186 per mile estimate for concrete paving.
However, factoring in maintenance and other factors, the actual 50-year life-cycle cost for bituminous is higher, at $1,981,795, compared to $1,713,904 for concrete.
Not only is the life cycle cost more than 13 percent less for concrete, according to Brunkhorst’s estimates, but there may be other benefits, such as less traffic interruption due to less frequent maintenance needed for concrete roads. Brunkhorst said delay factors for the traveling public, such as lane or road closures for maintenance, are not included in the cost of the projects, but will affect motorists.
Brunkhorst provided estimates for what he described as a typical bituminous road.
After initial construction, Brunkhorst expects bituminous pavement to require seal coating in the third year, and overlay work in year 12.
Seal coating will be required again in year 15, patching will be required in year 21, and seal coating will be required again in year 22. Additional maintenance will be required throughout the life of the roadway.
In contrast, concrete paving is not expected to require any maintenance until year 25, when minor work is required. After that, the next maintenance is not expected until year 39, according to Brunkhorst’s projections.
Brunkhorst noted most of the concrete county road projects in the state have taken place in the past 10 years, and the more concrete jobs there are, the more the cost tends to go down.
The first concrete county road project in McLeod County was on CSAH 5 in Winsted.
Brunkhorst said McLeod County has been among the leaders, but more and more counties are beginning to switch to concrete paving.
He said McLeod County recently upgraded part of CSAH 2 north of Silver Lake to concrete. He explained it was not on the county’s five-year plan to work on that road, but by tying the project to Wright County’s work on CSAH 3 running south from Cokato, McLeod County was able to get very good pricing to run concrete from CSAH 3 in Wright County to the portion of CSAH 2 that was already concrete, so he shuffled the five-year plant to do the work now.
Brunkhorst said there was a time when many county engineers avoided concrete and thought only MnDOT does county paving. Recently, however that has begun to change.
Brunkhorst said when he is looking at new construction, he will still look at bituminous, but he likes to use concrete where it makes sense.
One innovation that has been used in McLeod County for the past four or five years is dragging a couple of plates on the paver to create grooves in the concrete for road striping. This allows the stripes to be recessed below the road surface so plows don’t grind them off.
“It gives us built-in plow protection,” Brunkhorst said.
Some of Brunkhorst’s statewide data was provided by the Concrete Paving Association of Minnesota. More information is available on the association’s website, www.concreteisbetter.com.
For a contrasting view, the Minnesota Asphalt Paving Association supports asphalt versus concrete. That group’s website is asphaltisbest.com.