Two types of projects are considered here: (1) projects that involve studies outside the existing corridor or where a facility for more than one alternative mode of transportation may be involved, and (2) projects where feasible alternatives are limited to the existing corridor but did not qualify to pass directly to the design phase. The main difference between the two as far as processing is concerned is that the first group has not yet narrowed its alternatives down to feasible alternatives.
In each case, a project inventory is developed. This information includes historical sites; public recreational facilities; school, church, fire, and police districts; proposed development; land use; existing and other proposed transportation facilities; preliminary traffic assignments; and other similar social, economic, and environmental features, which are pertinent to the area under study. Using this information as a guide, all preliminary alternatives are developed together with documentation of the anticipated effects on community, preliminary cost estimates, and other technical considerations. Advantages and disadvantages of each alternative are studied. Where appropriate, coordination with other modes is considered. The “no-build” alternative is also considered and provides a reference point for defining potential beneficial and adverse impacts. Public hearings are held to gain input from the local public in the affected areas. Following an evaluation of all input received, alternatives are weighed and only those considered to be feasible are forwarded to the next step. From this point on, all projects in the preliminary development phase are on the same path.
Among the environmental concerns which must be considered for each alternative are the following (see also Chap. 1):
Air quality. A study of the effect of a proposed transportation improvement on the quality of the air
Historic or prehistoric. A study of the effect of the proposed transportation improvement on historic or prehistoric objects or on lands or structures currently entered into the National Register or which may be eligible for addition to the National Register
Endangered species. A study of the effect of the proposed transportation improvement on rare or endangered plants or animals having national or state recognition Natural areas. A study of the effect of the proposed transportation improvement on natural areas designated as having regional, state, or national significance Parks and recreation. A study of the effect of the proposed transportation improvement on publicly owned parks, recreation areas, or wildlife and waterfowl refuges designated as having national, state, or local significance
Prime farmlands. A study of the effect of the proposed transportation improvement on farmlands with high productivity due to soil and water conditions or having other unique advantages for growing specialty crops
Scenic rivers. A study of the effect of the proposed transportation improvement on any scenic rivers of state or national significance
Streams and wetlands. A study of the effect of the proposed transportation improvement on streams and wetlands on project and abutting land areas
Water quality. A study of the effect of the proposed transportation improvement on the quality of live streams or bodies of water
The next step is a refinement of feasible alternatives. This requires additional work sufficient to prepare an environment document. This could include such items as approximate construction costs; alignment and profile studies; typical section development; preliminary designs for geometric layout, drainage, right-of-way, and utilities; location of interchanges, grade separations, and at-grade intersections; preliminary bridge designs at critical locations; channel work; air, noise, and water studies; flood hazard evaluations; and other supplemental studies and right-of-way information. Once again, input is sought from the public sector through advertisement and public hearings.
Figure 2.1 shows the corridors for the feasible alternatives for an 11-mi relocation of U. S. 30 in Ohio (Ref. 13). The map is part of a study evaluating crossroad treatment for each alternative. Figures 2.2 and 2.3 show the projected crossroad treatments for the various alternatives. The options are (1) interchange, (2) grade separation, or (3) closing roads with cul-de-sacs. Since the proposed segment will be a limited-access highway, the option of at-grade intersection was not considered. Figures 2.4 and 2.5 show current and 20-year projected traffic volumes for all roadways. These are examples of maps used in the study of feasible alternatives.
After consideration of all the input and comparing the benefits and disadvantages of each alternative, the next step is to make a selection of the recommended alternative. This selection is certified by the state’s transportation director. Following approval of the environmental document, the project may proceed to the design phase.
