Paving Paradise

What is so rare as a day in June? An acre without a road through it, at least on the Front Range.

Road density along the Front Range roughly doubled between 1937 and 1997, swallowing up the wide open spaces in their wakes, according to a paper published today in the journal Science.

The researchers, led by Raymond Watts of the U.S. Geological Survey in Ft. Collins, found that Colorado’s Front Range lost about half of its roadless volume between 1937 and 1997 “as a result of urban expansion, growth of small towns, and housing dissemination — all occurring on agricultural land.”

Graphics accompanying the paper (shown below) demonstrate how rapidly the Front Range is succumbing to asphalt.Road density has been very controversial in the West, especially on national forest and Bureau of Land Managment lands. Several “roadless reviews” have been conducted amid enormous controversy to determine which federal lands are suitable for inclusion in the national wilderness system. But there hasn’t been a coherent general method to quantify roadless volume until now.

Fragmentation of wildlife habitat by roads has many negative effects. The authors write, “Roads have been demonstrated to have dozens, if not hundreds, of effects on ecosystems and watershed. Physical, chemical and biological processes transmit influences from roads to their surroundings.”

The authors used “pseudotopographic surface” to graphically show the road density. This shows on the graphics as pyramids. The larger the pyramid, the greater the distance between roads. So more and larger pyramids equals more roadless space, while few or no pyramids means that an area is virtually paved over.


In the graphics, road density volumes along the Front Range are mapped. In the “1937” image what appears as elevation is actually distance to the nearest road in Front Range communities in 1937. The larger the pyramid, the further the distance between roads, and the more open space there is. The other image shows that by 1997 the Front Range has lost half of its “pseudotopography.” That is, road density about doubled.

There are about 39 million miles of road in the United States. They fill the landscape so completely that, except for Alaska, you can’t get further than about 22 miles from a road anywhere in the lower 48 states.

On the other hand, the county with the lowest volume of roads per person in the U.S. is Hinsdale County in southern Colorado. The county with least roadless space per person in the U.S. is Kings County (Brooklyn), New York.