Highway design is only one element in the overall highway development process. Historically, detailed design occurs in the middle of the process, linking the preceding phases of planning and project development with the subsequent phases of right-of-way acquisition, construction, and maintenance. While these are distinct activities, there is considerable overlap in terms of coordination among the various disciplines that work together, including designers, throughout the process. It is during the first three stages: planning; project development; and design; that designers and communities, working together, can have the greatest impact on the final design features of the project. In fact, the flexibility available for highway design during the detailed design phase is limited a great deal by the decisions made at the earlier stages of planning and project development. This Guide begins with a description of the overall highway planning and development process to illustrate when these decisions are made and how they affect the ultimate design of a facility. Although the names may vary by State, the five basic stages in the highway development process are: planning, project development (preliminary design), final design, right-of-way, and construction. After construction is completed, ongoing operation and maintenance activities continue throughout the life of the facility.
The initial definition of the need for any highway or bridge improvement project takes place during the planning stage. This problem definition occurs at the State, regional, or local level, depending on the scale of the proposed improvement. This is the key time to get the public involved and provide input into the decision-making process.
The problems identified usually fall into one or more of the following four categories:
Whichever problem (or set of problems) is identified, it is important that all parties agree that the problem exists, pinpoint what the problem is, and decide whether or not they want it fixed. For example, some communities may acknowledge that a roadway is operating over its capacity but do not want to improve the roadway for fear that such action will encourage more growth along the corridor. Obtaining a community consensus on the problem requires proactive public involvement beyond conventional public meetings at which well-developed design alternatives are presented for public comment. If a consensus cannot be reached on the definition of the problem at the beginning, it will be difficult to move ahead in the process and expect consensus on the final design.
At the State level, State DOTs are required to develop and maintain a statewide, multi-modal transportation planning process. Broad categories of highway improvement needs are defined, based primarily on ongoing examinations of roadway pavement conditions and estimates of present-day and 20-year projections of traffic demands. In addition, each State is required to conduct biennial inspections of its major bridges (and similar, less frequent, inspections of minor structures) to determine their structural adequacy and capacity. In a number of States, regional transportation plans for multiple counties are prepared within the context of the statewide planning process. Every few years, the State selects improvement projects based on the long range-plan and includes them in the Statewide Transportation Improvement Program, or STIP.
Source: Flexibility in Highway Design pp. 2-4
Published: 1997
