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Presenting Nature
MENU
Design Ethic Origins
(1916-1927)
Design Policy & Process
(1916-1927)
Western Field Office
(1927-1932)
Decade of Expansion
(1933-1942)
State Parks
(1933-1942)
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Presenting Nature:
The Historic Landscape Design of the National Park Service, 1916-1942 |
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IV. THE WORK OF THE WESTERN FIELD OFFICE, 1927 TO 1932 (continued)
DESIGN OF PARK ROADS (continued)
TREATMENT OF ROAD BANKS
One of the most significant advances made by the Landscape Division in the design of park roads was the naturalistic treatment of the earth cuts and filled slopes created during construction. Although Hull had called for the finishing of the banks alongside roads by shaping them into slopes in the early 1920s, it was not until 1929 that a technique for rounding and flattening slopes was developed and institutionalized. That year, Vint's office issued four cross-section drawings for the slopes of earth cuts and fill areas along national park roads under construction by the Bureau of Public Roads. The diagrams introduced a technique to round the tops of cut and fill slopes and to flatten the slopes so that they attained a proportion of 3:1. Slopes were not to exceed a ratio of three feet in depth for every one foot of elevation. This technique would become a major characteristic of park roads and parkways. It made it possible to ease the disturbed slopes gradually into the surrounding landscape and helped reduce erosion. Once graded in a graceful slope, the banks would be able to recover vegetation naturally or could be sodded and planted so that they blended into the natural vegetation of the surrounding woodlands or hillsides. [21]
The idea of creating continuity between a roadway and the surrounding landscape by flattening the slopes was first developed by John C. Olmsted in an article in Garden and Forest in 1888. Olmsted warned against leaving too steep an incline along roads because of erosion and difficulty in mowing and maintenance. He suggested "lessening the incline to avoid unnatural appearances" by learning from nature how to make an ogee curve by combining concave and convex arcs and by varying their proportions to "produce an undulating surface, graceful if grace is a quality to be desired in the locality, but in all cases informal and natural." He advised his readers to vary the distance and the shape of the slope to take advantage of the configuration of the adjoining ground and to use existing trees or rocks as suggestions for determining "where to widen the slopes and the road or to make them more gentle." In a series of simple diagrams, Olmsted illustrated how the length and height of the concave and convex surfaces of an ogee curve could be manipulated to adjust a roadway to the surrounding topography. [22]
Henry Hubbard encouraged his readers to follow Olmsted's advice and to study natural conditions to create a "sequential and smooth flow of surface." He wrote,
A judicious choice of variety inform and steepness of slope, special care in the junction of the new surfaces with the old, and studious avoidance of unduly symmetrical forms or straight lines or sharp angles—at least when dealing with soft materials— will produce a form unity between the designer's work and the landscape which will go a long way towards unifying the composition which includes both. [23]
In summer of 1930, Director Albright gave Vint authority to forge ahead with improving the standards for national park roads. By the following spring, Vint had issued more advanced diagrams for the treatment of slopes. These illustrated typical cross sections for rounding slopes, twenty feet in depth or less, and included directions for warping the ends of the cuts to enhance the naturalistic appearance of the slopes. Adherence to the diagrams became a specification in all new contracts. The Bureau of Public Roads readily accepted the designs and put them into use throughout the national parks. Within four seasons of use, the treatment was adopted by several other road-building agencies and was being widely used in national forests and other federal lands. [24]
The Landscape Division's technique for treating slopes had many advantages. First of all, by rounding the edges of cuts, road builders could erase the most conspicuous trace of human intervention—the ragged, unnatural line of the cut. Flattened into proportions more similar to the natural angle of repose, the slopes could provide a graceful transition from the natural woodland or meadows beyond the road to the roadway itself. From a practical standpoint, slopes that had been rounded and flattened were less vulnerable to erosion and more quickly able to recover vegetation by natural means, through wind dispersal of seeds or through propagation from the surrounding woods or meadows.
The treatment of the slopes of park roads continued to be studied and improved. By 1932, the results of the rounding and flattening of cut slopes were apparent from decreasing maintenance costs and improved appearances. The division further examined the treatment of road shoulders, width of slopes, and size and types of ditches. Designs for drop-inlets, ditches of crushed stone and loose gravel, and other solutions were introduced in the early 1930s to improve the drainage along park roads. The Landscape Division continued to make improvements in the cross sections for park roads, refining the treatment of rounding and flattening the slopes. When revised specifications were issued in 1938, the ratio had been increased from 3:1 to 4:1, flattening the slope to an even greater degree. These new designs went hand-in-hand with the advances made, primarily through parkway development, in the use of transitional spirals and superelevations to create graceful curving roadways along steep inclines. [25]
NATURALIZATION OF ROAD BANKS
Although many slopes quickly reverted to natural conditions, erosion on newly cut and shaped slopes was a constant concern. At the same time that Vint's staff was developing ways to blend road banks into the scenery by rounding and flattening the slopes, they became interested in the possibilities of speeding up and controlling the process of revegetation by planting or sodding the finished slopes. Practical concerns about erosion, maintenance, and visibility were coupled with an interest in returning the roadsides to a scenic and naturalistic appearance. Planting the roadsides added to their beauty and created a pleasing sequence of effects, particularly where there were no distant views.
The park service's interest in treating the slopes of park roads coincided with a growing interest nationally in planting highways for scenic beauty. Articles on the topic by noted landscape architects P. H. Elwood, Jr., Jens Jensen, Warren Manning, and Frank Waugh appeared in Landscape Architecture in the late 1920s and early 1930s. Several states had extension programs or state highway programs that performed planting as a form of beautification. Since the mid-1910s, Illinois had promoted planting native trees and shrubs alongside rural roads to improve the beauty of the countryside and "restore" the character of the native prairie. Jens Jensen had designed the planting for the ideal section of the Lincoln Highway in the Midwest, and Massachusetts, Pennsylvania, and several other states were planting flowering shrubs and other plants along highways.
Hubbard suggested that slopes be held in place by roots of vegetation or by boulders. The final form and slope of road banks was to be determined by the geologic composition of the natural site and the physical characteristics of available materials, such as vegetation and boulders. Hubbard preferred plantings that developed the particular character of the landscape through which the road passed. In a naturalistic design, Hubbard recommended informal plantations of trees and shrubs so that the road appeared to run through preexisting groups of foliage. [26]
The most scientific theory on roadside planting was put forth by Frank Waugh in "Ecology of the Roadside," published in Landscape Architecture in 1931. Waugh applied ecological principles to the natural growth and planting of roadside vegetation. He wrote of species that thrived along the roadside:
These species are distributed according to the varying amounts of light and moisture, some occupying one station and some another. Now the road is apt to be very dry in the center and along the immediate margins; it usually grows more moist further from the center, until there may be at last a roadside ditch with running or standing water in it. Here plainly one type of vegetation would be found at the dry edge of the roadway while a very different type would occur in the wet ditch. These differences, and others of the same order, are responsible for the great and delightful variety in roadside vegetation. [27]
Waugh recognized the potential of this phenomenon for road design. Again, Waugh applied the idea of zones to studying the natural arrangement of plants along the roadside. To Waugh, a knowledge of vegetation was necessary to preserve landscape character and maintain it. He criticized the careless and destructive mowing, slashing, and clearing of roads in the country and forest lands:
They have a strong tendency to destroy the natural order of plant development, sometimes entirely eliminating shrubbery or herbaceous species, which, from the standpoint of roadside beauty, are highly desirable. Of course, it is necessary at times to cut back the roadside vegetation to keep it from choking the passage entirely, especially along woodland trails or on roads which are not much used; but manifestly such clearings ought to be made with great care, having full respect to the natural order of vegetation and preserving as far as humanly possible all the most attractive plant colonies and zones everywhere. [28]
Waugh, of course, found the planting of trees in equally spaced rows to be out of place in natural parks, except on short and formal approaches to an administration building or architectural group, or where they enframed a parking area or playing field. He felt it much better to make planting informal, following the zonal principle with "large growing trees, such as maple, oak, tulip tree, and pine set in forestlike masses or in quite irregular groups." [29]
National park landscape engineers began to give attention to vegetation along park roads in the late 1920s. Among the first planting efforts were experiments Davidson conducted in 1927 along the banks of new roads in Mount Rainier. In three separate areas, Davidson planted brake ferns, cuttings of salal, and cuttings of thimbleberry and common huckleberry The expanding interest in roadside planting coincided with the National Park Service's 1930 policy excluding all exotic seeds and plants from the national parks, with the exception of nonnative grasses, which were impossible to control and already abounded in parks. Roadside grading and planting became one of the most important and widespread activities of the Civilian Conservation Corps in national parks. In many parks, experimental plots for grasses, perennial herbs and wild flowers, vines, and shrubs were maintained, some in conjunction with the natural history programs and museum gardens. [30]
In many locations the banks of new roads rapidly recovered a ground cover through natural seeding. In others planting and stabilization were necessary to control erosion. After being flattened and rounded, slopes were planted with the seeds or seedlings of native grasses and herbaceous plants, including wild flowers. Experiments were often conducted before planting, from seeds collected locally in previous seasons. Temporary log cribbing was constructed on particularly steep slopes subject to erosion. To catch runoff, gutters were dug and in some places lined with stones. Rocks were also artistically embedded in slopes for stabilization and erosion control.
At Yosemite, serious erosion problems in the cuts along the Wawona Road and difficulty in getting vegetation to take hold naturally led to a cooperative study with the park's natural history program. Dr. Frederic E. Clements of Carnegie Institution, who had done extensive research on plant ecology and operated a field station in Santa Barbara, California, directed the program in the early 1930s. Various experiments were conducted involving seeding and sodding slopes, installing wooden cribbing to hold seedlings in place, and planting creeping vines and other plants in the interstices of rocky slopes. Techniques were developed for erasing the line between the natural woodland or meadow and the cut-and-fill slopes by clearing vegetation before construction along an irregular line and replanting likewise with species appropriate to the area. Sections of the Yosemite Museum's garden were set aside for experiments. Enrollees from one of the park's Civilian Conservation Corps camps carried out the work of collecting seeds and planting the slopes.
By 1930, Vint added planting to an expanded definition of roadside cleanup, which was funded under annual appropriations for roads and trails. Cleanup now assumed great importance as one of the principal means by which the landscape designers could uphold the natural beauty of the park and erase the scars of development. The naturalization of roadsides after construction was added to the already routine practices of screening undesirable views, opening up scenic vistas, clearing dead and decaying timber from the roadside, and placing telephone lines underground. Cleanup also included small-scale improvements at parking turnouts and roadside springs, such as water fountains, curbs and sidewalks, and benches. [31]
By 1931, the preparation of slopes for natural reseeding or for planting was routine. Duff, or the top layer of soil, was removed from the slopes before construction, stored, and reapplied on finished fill slopes. The duff improved the appearance of the soil and helped blend it with the undisturbed duff of the surrounding woodland. Spread on the slopes after construction, it encouraged regrowth of natural vegetation and provided fertile ground for planting seeds or cuttings. In some cases, sod was removed from the rights-of-way and transplanted where needed. Vint reported his satisfaction, saying, "Our efforts toward protection of the roadside and natural landscape are also showing encouraging results." [32]
As more and more attention was given to vegetation, so too were ways sought to blend the newly planted banks into the natural surroundings. A technique of bank blending emerged in which trees cleared for the construction of roads were cut in swaths having an irregular uphill or downhill edge line. This technique eliminated the artificial appearance of a straight, regular line and created a wavering, curving line that appeared naturalistic. Shrubs, ground covers, and woodland plants could be planted along these edges in a natural succession, further erasing the line between planted areas and natural areas. Hazards from falling limbs and the risk of obscuring the motorist's vision generally made saving trees within the road cross sections impractical. It was far better to clear the trees and replant the new slopes, the location of the road having been selected to avoid trees or rock formations of importance.
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| In the mid-1930s, the Civilian Conservation Corps shaped the slopes of the newly constructed North Rim Road in Grand Canyon National Park according to the techniques for rounding and flattening the slopes and blending the banks into the surrounding forest. This work greatly reduced soil erosion along new roads and created the illusion that nature had never been disturbed. (National Archives, Record Group 79) |
Among the many conservation projects carried out in national parks by the Civilian Conservation Corps in the 1930s, the sloping and naturalization of road banks left by cut-and-fill operations during road and trail construction was one of the most important and widespread. It had an important role in controlling slope erosion as well as lasting value for beautification. Landscape architect Davidson recognized the practical and aesthetic value of this work in 1934, when he stated that the stabilization and naturalization of the cut-and-fill scars resulting from road and highway construction was the most important work carried out by the Civilian Conservation Corps in the national parks.
Such erosion control work is not merely an excellent landscape betterment, but will make road and trail maintenance work immensely easier and more economical. We should not consider that Erosion Control work has been completed in the park until every cut and filled slope along all roads or trails has been stabilized to a point where there is no more erosion either from slides, rainfall, or other natural conditions except accidental occurrences. We need not go into the many methods from which the best should be selected to apply to each project, it is sufficient to mention here that any method will result in greatly increased roadside beauty when stabilization is actually accomplished. [33]
The contouring and naturalization of road banks had many useful applications for other aspects of design in both national and state parks. These include the rounding, flattening, and planting of slopes alongside trails, at parking areas and overlooks, and on other embankments where a gradual and naturalistic transition between a developed area and the natural park surroundings was desired. It was particularly valuable where practical necessity required the creation of a flat, level plaza in an otherwise naturally contoured area. This technique would also prove invaluable in stabilizing streambanks and enhancing their aesthetic appeal by reducing erosion and the buildup of debris in snags. It would also add to the beauty and naturalistic character of the shorelines of the newly constructed lakes developed for recreational purposes in state parks and recreation demonstration areas in the 1930s. This contouring technique, combined with naturalistic plantings, contributed greatly to returning construction sites and other disturbed areas to naturalistic appearances.
The National Park Service was a pioneer in what became in the 1930s a nationwide movement for roadside beautification and soil conservation. Through the efforts of the Soil Conservation Service and many state highway departments, roadside planting with flowering shrubs, perennial herbs, ferns, and ground covers became routine practice nationwide in the 1930s. The park service's work represents an important stage in the evolution from the English gardening tradition to the present-day standards for highway design. By translating John C. Olmsted and Henry Hubbard's ideas for treating slopes into modern design theory that was institutionalized by the Bureau of Public Roads, national park designers contributed substantially to twentieth-century landscape architecture. Their innovations in treating the banks of roads would have lasting influence on the character of modern highways, as well as on the development of roads in national parks, national forests, and state parks. Because the techniques proved economical and reduced the potential for erosion, they were adopted to control erosion along streams and embankments in park areas other than roads. By blending and warping slopes and ensuring the regrowth of vegetation, the designers of national park roads also drew attention to the natural character and inherent beauty of native vegetation. The work of the park service in roadside planting and the early work of state highway departments in Illinois, Massachusetts, New York, and Pennsylvania together laid an aesthetic and practical foundation for the current movement for highway beautification and scenic byways and for such programs as Operation Wildflower, cooperatively run through the Federal Highway Administration and state highway departments.
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Last Modified: Mon, Oct 31, 2002 10:00:00 pm PDT
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