Rubble as road base jury is out

Dear Mahatma: Several years ago when a section of Interstate 40 in west Arkansas was being reconstructed there was an article in the paper about an experiment using broken concrete from the old highway in the new construction. Observers from several states were on hand to learn about the new process. Was that experiment successful, cost-effective, still being used? — Curious in the Village

Dear Village: This was an exercise in rubblization, about which we are fixing to tell you a bunch, including that the technique is not currently being used in Arkansas, but was deemed a success when it was.

Rubblization and overlay is a concrete pavement rehabilitation technique that prevents cracking and provides a solid base for new pavement. A breaker machine breaks up the pavement into small pieces at the top and larger pieces at the bottom. The rubble is then compacted and hot-mix asphalt is laid over.

The process, according to the Arkansas Department of Transportation, saves time and resources, given that the old roadbed doesn’t have to be carried off as waste. The rubble machine also moves fast, up to a lane-mile a day.

A total of 276 miles of pavement were rubblized in Arkansas in the early 2000s. We remember it well, especially around Clarksville.

ArDot, the Arkansas Asphalt Pavement Association and the Federal Highway Administration hosted a seminar and field visit in June 2001. About 240 people from 17 states attended and then visited two construction sites on Interstate 40 near Russellville.

How come no more rubblization projects since then? The answer comes from Mike Fuggit, ArDot’s assistant chief engineer for design.

ArDot evaluates rubblizing on concrete pavements that have lived, or outlived, their life expectancy, he said. As other concrete pavements reach that point, rubblization will be considered to determine if it’s the right technique.

Vanity plate seen at the airport: SOO OUI.

Hello: As you leave Interstate 430 south at the outlet mall exit there’s a curve overlooking the Harley Davidson store. The drop-off is very steep and could cause an inattentive driver or motorcyclist to go sailing over the embankment, potentially crushing many motorcycles or shoppers. Why isn’t there a guardrail to prevent such a tragedy?

— Concerned Former Motorcyclist

Dear Motorcyclist:

We have misty watercolor memories of asking this question once before. It was during the tenure of another chief engineer, cook and bottle washer for District 6 of the Arkansas Department of Transportation. Let’s ask the new engineer, Deric Wyatt.

Turns out his answer was essentially the same as that of his predecessor. That is, the side slopes of the embankment were designed and constructed to meet standards set by the Federal Highway Administration. The clear zone — the area safe to use by errant vehicles — for an interstate highway is typically 30 feet. This zone exceeds that distance.

If any location has a high rate of accidents, Wyatt added, it would be reviewed for safety improvements.

Vanity plate seen at UALR: LOGO.