In succeeding years hydraulic research for the Federal Highway Administration has been conducted on hydraulic roughness of corrugated metal pipes by the U.S. Waterways Experiment Station, on use of riprap[N 1] to minimize scour at culvert outlets, on unsteady flow in a pipe at Colorado State University, and on design of riprap lining for open channels at the University of Minnesota, not to mention numerous smaller studies undertaken elsewhere, usually in cooperation with a State highway department.
- ↑ Riprap is a layer, facing or protective mound of stones, concrete, or other material, randomly placed to prevent erosion, scour or sloughing of a structure or embankment.
Roadside Development
One of the earliest publications to identify the elements of and the need for improved road environments was by Louis C. Haupt in 1891.[1] His theme was that good roadside development is a move toward better roads. Little further attention was given to this subject until the early 1930’s when AASHO and HEB organized their first roadside committees; at that time only 10 States were represented. Even then, where roadside improvement was performed, it was done years after the highway was constructed.
Finally, however, the research and development work of the committees, with support from the Bureau of Public Roads, received progressively greater attention, and for some 20 years adequate roadside treatment has been a recognized part of design and construction. Roadside development research has covered such areas as erosion, esthetics, rest areas, resource conservation, planting and vegetation management.
The large number of studies and reports in this area of research was oriented mostly to local problems and conditions. A 1972 study showed that roadside development efforts still seem to be very much a local matter. Efforts to broaden this activity on a national scale have thus far met with little success.
Vegetation Management
A major part of roadside development is vegetation management. For 50 years, most of the work was directed toward the prevention of erosion. While erosion control is still a primary goal, for more than a decade the Federal Highway Administration and most States have recognized other values in vegetation. Research was directed to the selection of proper vegetation to encourage the establishment of certain species of wildlife. In addition, the esthetic value of vegetation is recognized for its potential in maintaining balance between the highway and the natural environment.
During the 1920’s and 1930’s, maintenance of roadside vegetation was usually done by hand. Although research had greatly improved mowing equipment and techniques by 1960, breakthroughs in the use of herbicides greatly altered roadside maintenance techniques. As this work progressed, however, concern over the long-term effect of herbicides created new interest in development of dwarf ground covers.
Today, with rising maintenance costs and public concern for our environment, the need is recognized for a highly refined roadside development program. Research and implementation efforts by FHWA, State agencies and others are focused on reduced mowing, refinement of herbicide technology, and the development and selection of vegetation that will reduce maintenance costs and enhance the overall environment.
Recent Environmental Research
In the past 10 years, two areas of interest have been receiving considerable attention: (1) Firm criteria for esthetic enhancement of the view from the highway are evolving from key studies and are having a major impact on new highway design and upgrading of existing roads, and (2) the need to protect the wildlife environment has opened a broad vista of studies addressing the compatibility of small and large game, birds and fish with the highway environment.
Work on erosion control, roadside vegetation, management transportation economics, and hydrology were the forerunners of today’s environmental research. This was highlighted by the establishment of a formal research program in environmental design and control. In response to the National Environmental Policy Act of 1969, the research is directed to understanding the interaction between highways and the environment and developing technology to protect the environment.
Since 1970 this research has dealt with a wide range of environmental elements including air, noise and water quality; social and economic effects; roadside rest areas; sewage treatment; vegetation management; esthetics; water runoff; de-icing chemicals; spills of hazardous materials; erosion control; and wildlife.
In summary, roadside development has progressed during the past 50 years from a somewhat haphazard approach to a highly sophisticated and comprehensive science.
Nationally Coordinated Programs
In the early 1960’s several significant events led to dramatic changes in the concept and activity of highway research. Enlarged research and development legislative authority was enacted in 1962 and made effective beginning with fiscal year 1964. There were growing problems for highway transportation along with population growth, urban concentration, and changing national priorities and goals.
One major legislative change was the requirement that 1½ percent highway planning and research (HPR) funds must be used for planning and research purposes. No longer was there an option of using this money for construction. This requirement ensured the strength and vitality of federally aided planning and research programs in the States. Another event was the organizational separation of planning and research in the Bureau of Public Roads late in 1961. Research and development finally became a formal separate program in the Bureau.
351
- ↑ Roadside Development—Evaluation of Research, NCHRP Report No. 137 (Highway Research Board, Washington, D.C, 1972) p. 45.
