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Federal Highway Administration Research and Technology
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|Publication Number: Date: Spring 1995|
Issue No: Vol. 58 No. 4
Date: Spring 1995
In Wyoming's Grand Teton National Park, magnificent snow-covered mountains rise high above the valley of Jackson Hole, reaching an elevation of nearly 4,300 meters. Quiet lakes, tumbling waterfalls, and rippling streams sparkle in the sunlight. Sweet-smelling forests of lodgepole pine and alpine fir stand tall against mountain meadows of wildflowers; aspens and cottonwoods are starkly, brilliantly yellow against a blue sky. Bald eagles soar high, sharing the skies with rare and graceful trumpeter swans, white pelicans, and sandhill cranes. Herds of shaggy, brown, muscular bison move slowly along the banks of the Snake River. Deer, bear, and moose roam free. Coyotes yip and yowl by night, while the high, haunting bugle call of the bull elk echoes among the canyons by day.
Each summer, 3 million visitors come to Grand Teton National Park to experience its vast array of wildlife, its outstanding beauty, its spirit of wildness. They come in sedans and station wagons and vans, in pickup campers and travel trailers and motor homes and tour buses. These vehicles need roads, and they need parking lots.
In a series of projects, the Federal Highway Administration (FHWA) is designing and reconstructing roads and supplementary facilities for Grand Teton National Park. FHWA's greatest challenge is to provide adequate facilities while preserving the park's wild -- but delicate -- beauty.
Can this be done? Let's look at one of FHWA's several projects in Grand Teton National Park. This project includes the relocation of a portion of Teton Park Road (one of two major routes through the park), the rebuilding of Jenny Lake Road, the relocation of String Lake Road, the construction of six parking areas, and the obliteration of several abandoned road sections.
Built nearly 50 years ago, Teton Park Road was too narrow for the motor homes and tour buses that constitute a large portion of today's traffic through the park. The pavement was thin, and the road's foundation had pockets of unstable material. In short, Teton Park Road could not support the heavy traffic that used it; its surface was cracking and had large ruts.
The segment of the old Teton Park Road involved in our project included a 4-kilometer tangent that went through a tedious sagebrush flat. This straight stretch encouraged high-speed travel and offered few views of the mountains. FHWA engineers designed a longer 5.5-km route that climbs the sides of glacial moraines and winds through a forest of lodgepole pine. They designed a graceful, lower-speed road that blends with the surrounding terrain and provides a series of sweeping views of Mount Owen, Teewinot, Mount Moran, The Grand, and vistas of other high peaks that previously had not been accessible to park visitors.
The grade of the new road closely followed the contours of the ground. Cuts and fills were minimized, and slopes were rounded to blend with the contours of the natural terrain. Topsoil, which crews saved during construction, was placed over the cut-and-fill slopes.
Because temperatures in the Tetons can drop to minus 40 degrees Celsius during winter, FHWA paved the road with a polymer-modified asphalt concrete that resists thermal cracking. Material that contained a mixture of crushed aggregate, silt, clay, and organic matter was placed outside the pavement edges. This combination will support the growth of grasses and wildflowers alongside the pavement.
The original Jenny Lake Road was an 8.5-km, single-lane, one-way loop. Its pavement was badly deteriorated, and motorists spent more time watching for potholes than looking at the park's scenery. The road had no base rock, and directly beneath its pavement were the stones and boulders that had been deposited tens of thousands of years ago by Jackson Hole's last glacier.
The north portion of Jenny Lake Road passed through an elk-calving ground. In spring, traffic disturbed the elk and their young calves. This part of the road was abandoned, and a new cutoff was constructed from Teton Park Road to Jenny Lake Road.
The middle portion of Jenny Lake Road was reconstructed as a two-way facility. The loop's original one-way configuration was a nuisance for the many visitors who wanted to picnic, canoe, and hike in the String Lake area but did not want to drive the entire loop. So, the middle portion of the road was constructed to the standards used on Teton Park Road; the long straight stretches of the original route were changed to provide a flowing alignment.
The south portion of the loop followed the shore of Jenny Lake, whose blue waters lie directly below the sharp snowy pinnacles of the Tetons. To preserve the sense of a rustic road that wanders through the woods and along the lake's shore, the only construction work performed along this portion of the loop was to overlay the surface with polymer-modified asphalt concrete.
String Lake Road provides access to trail heads, a choice picnic area, and two lakes popular among canoeists. The original road had been built adjacent to String Lake, and traffic detracted from the lake's tranquility.
The road was very narrow, and the road's edges were lined with logs to keep vehicles on the pavement. When two motor homes met, one would have to back up into a parking lot. Sometimes an entire string of vehicles had to back up.
The new road, 7.3 meters wide, stays well away from String Lake and follows the natural contours of the ground.
The road's subgrade is depressed below the natural ground and filled with base rock. The paved surface is flush with the natural terrain. No ditches are required because the ground is composed of free-draining glacial debris.
The new road has no cut or fill slopes, and the natural vegetation remains undisturbed to within several centimeters of the pavement's edge.
Around the project's six new parking areas, a total of 3.3 km of cast-in-place curb and gutter was constructed. To provide a rustic appearance, the curb and gutter were given an exposed-aggregate surface, and sidewalks for the parking areas were finished with seed rock.
The original parking areas along String Lake Road were inadequate. They consisted of dirt, rocks, and numerous potholes. They were dusty in dry weather and muddy in wet weather. Also, they were too small -- frequently filled with vehicles by mid-morning.
Three new parking areas were constructed in the vicinity of String Lake. The largest holds more than a hundred vehicles. It has additional oversized spaces for buses and motor homes and an area for horse trailers.
The National Park Service was concerned that these large parking facilities would look like shopping center parking lots. Careful planning and construction have ensured that they do not.
The facilities are located not in natural open spaces, as past logic would have dictated, but amid stands of pines. The pines hide the parking areas, and the open spaces with their wildflowers remain undisturbed. The parking areas are not vast flat rectangles of pavement; they curve with the contours of the land. Even the largest parking area does not seem particularly big. The tree-covered median strips ensure that only a portion of the lot is visible from any vantage point.
Storm-water runoff from parking areas can become contaminated with spilled oil, fuel, and antifreeze. To ensure that this runoff would not contaminate the untainted waters of String Lake, crews installed dry wells beneath the surface of the parking areas to capture the runoff.
During construction, the subgrade of each parking area was depressed below ground level. Consequently, the tops of curbs and sidewalks were built flush with the natural terrain. The parking areas seem snuggled into the contours of the ground. Crews took great care during construction to ensure that the vegetation and ground were not disturbed outside the curbs. As a result, trees crowd against curbs and sidewalks. Now, as visitors step from their cars they do not feel as if they are in a parking lot but in the woods.
As a result of the reconstruction, nearly 9 km of road were abandoned and turned back to nature. Crews broke the surface of these old roads and hauled the debris to the Timber Island borrow pit, where they buried it. Cuts and ditchlines were filled in, and embankments were removed. The ground was restored to its original contours. Topsoil -- a precious commodity in the rocky Tetons -- was conserved during construction and spread over the sites of the old roadways. Laborers finished the topsoil by hand and prepared it for seeding with indigenous grasses.
This project was the last to use the Timber Island borrow pit, which had been in use for half a century. The pit had served not only as a materials source but also as a garbage dump -- and it looked it. Its appearance clashed with the magnificent beauty of the mountains above.
As the project drew to a close, debris and garbage from the Timber Island pit were buried. The pit's slopes were recontoured, and topsoil was placed over them. Finally, the Timber Island access road was obliterated. The old Timber Island pit and the former routes of Teton Park Road, Jenny Lake Road, and String Lake Road are memories.
To preserve a sense of wildness, careful planning and great attention to detail are required, but not necessarily a lot of expense. This project included the reconstruction and partial relocation of 8.7 km of highway, the overlay of 2.7 km of existing road, the construction of six parking areas, the obliteration of 8.8 km of old road, and the rehabilitation of a large borrow pit. The total cost for this work: $3,032,000.
Was FHWA successful in its efforts to provide adequate facilities while preserving the park's outstanding beauty? This summer, take a trip to the Tetons. If you gaze in awe at the peaks looming overhead, at the blue perfection of a lake, at a deer slipping through the pines -- and if you forget that you're standing in the middle of a parking lot -- then the answer is yes.
Gary Hunter is a project engineer with FHWA's Western Federal Lands Highway Division. Over the past nine years, he has worked on a series of projects in Grand Teton National Park. He has been an engineer for the Federal Lands Highway Office since 1970 and has been assigned to construction projects in several Northwestern states. He has a degree in mechanical engineering from Oregon State University.