ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Thursday, January 11, 1996 TAG: 9601110071
SECTION: VIRGINIA PAGE: C1 EDITION: METRO
COLUMN: What's On Your Mind?
SOURCE: RAY REED
Q: I recently made a trip from Botetourt County, home of the infamous washboard highway, to Florida and Mississippi. In these states it seemed that the concrete highways were breaking up. Asphalt is much smoother to drive on, so is there any real advantage to using concrete?
J.S., Troutville
A: Concrete is still a viable highway surface; it can yield longer life and requires less maintenance.
Asphalt's advantages include a lower cost up front and smooth ride as long as the surface holds.
Concrete typically costs more when building the original highway. But if the right ingredients and support materials are used, concrete highways can last up to 30 years without costing a lot for maintenance.
However, asphalt may be smoother because it most likely has been resurfaced fairly recently. It's the material of choice in many new highways.
About now, you may be thinking that stretch of concrete on Interstate 81 in Botetourt didn't last anywhere near 30 years before it needed the resurfacing that was partly completed last year.
You're right. Botetourt's concrete developed the washboard feature long before it was expected, primarily because the clay soil trapped moisture under the road's surface.
Most concrete interstates were built the same way back in the mid-1960s, using specifications developed on a test road at Ottawa, Ill., about 60 miles from Chicago. Clay apparently was not a factor in the test.
All over the country, local soil conditions and available building materials were used in an effort to duplicate the test road. Results were better in some states than others, but we're seeing a lot of rough concrete now.
Another problem that surfaced early on roads built to the test standard was traffic volume. It had been underestimated, and the concrete's durability limit was reached sooner than expected.
On the positive side, engineers have learned how to build concrete roads that last longer.
The decision on concrete vs. asphalt is as much philosophical and political as it is practical.
Do we want to spend the extra money up front for concrete, and take the road out of use for three weeks while the surface hardens?
Or do we opt for asphalt, and resurface every five to eight years? Asphalt's higher maintenance costs can be offset on busy roads by swifter return to normal traffic flow. New asphalt can support heavy trucks just a few hours after being laid.
Also, asphalt's recyclable. Old pavement can be used to make new asphalt.
Insight into why concrete roads can stay rough for a long time before resurfacing was offered by Larry Smith, a spokesman for the Florida Department of Transportation:
If they build a road with the promise that it will last 30 years, budget-makers don't plan to spend on maintenance until the time's up. If the road starts breaking up in 20 years, repair money will be scarce.
"It is not a catastrophe if a road gets rough. If a bridge falls, that's a catastrophe," Smith said. The best concrete is used in bridges.|
Got a question about something that might affect other people, too? Something you've come across and wondered about? Give us a call at 981-3118. Maybe we can find the answer.
LENGTH: Medium: 67 linesby CNB