Roadless Space Uneven Across U.S.

May 3, 2007 — A new method for evaluating the land in between roads could improve efforts to preserve wild areas and plan urban communities.

In the continental United States, roads are never more than a reassuring 22 miles away. Their ubiquity makes travel and transport convenient for people, but it can also fragment or destroy wildlife habitats, help introduce invasive species, and contribute to pollution.

The further an environment is from a road, the less it is affected by those things. But traditional tools for analyzing roadless space have ranked a plot of land one mile from a road the same as one several miles from a road.

The new method for evaluating roadless space takes those differences into account.

"Having a way to measure roadless space is a very general way of expressing how much natural landscape we have out there. Our metric, at most, bends over backwards to express the invulnerability of that area," said Raymond Watts, a scientist at the Rocky Mountain Geographic Science Center and USGS Fort Collins Science Center in Colorado.

Watts and his colleagues published the results of their study in this week's issue of Science.

The researchers compiled roadless space data in 100-foot intervals, county-by-county, across the 48 contiguous United States.

They calculated the remoteness of each point, converting the numbers into an altitude-style set of markings. The result is a map of peaks and valleys, where sections of land farthest from a road have the highest rise, and areas closest to roads have the lowest.

Not surprisingly, the least roadless space exists in New York — Brooklyn to be exact. In contrast, Hinsdale County in southern Colorado has area farthest from any road in the country.

Watts and his team were surprised to see that just as mountains and deserts contain few roads, so too do areas with abundant water, such as the inaccessible Lousiana bayous, Florida Everglades, and the lake region of northern Minnesota.

And when the scientists compared the roadless space with the number of people in a given area, they sometimes found a mismatch: that is, too many roads for too few people.

But "roads" in the case of this study are anything from jeep trails to multi-lane highways, with no distinction made between one or the other.

However, said Kent Cavender-Bares, a researcher at the H. John Heinz III Center for Science, Economics and the Environment, in Washington, D.C., the study "could be viewed as an interesting first step, and one could imagine subsequent analysis that would repeat this approach, taking road size or some other aspect, such as volume of traffic, into account."

With that information, park managers and urban planners alike will be better equipped to make decisions about where a new road might be best placed and where older, unused roads could be eliminated.