Practical Solution Concepts for Planning and Designing Roadways

Abstract

Developing a procedure that yields up to the maximum margin of return for the investment requires an approach that takes into account specific safety issues and the commensurate design elements for each roadway. Kentucky’s highway agency has embarked upon an initiative tagged “practical solutions” which sets its goal toward reducing costs throughout the project development process extended into operations and maintenance of all highway facilities. This operationally defines a design procedure within the context of practical solutions and sets up the guiding principles of the approach. The most critical component of practical solutions in planning and design is the definition and clarification of the initial project concept (its specific goals and objectives) since it is the corner stone of the project and used to significantly contain the cost and impact of a project. Traditional design tends to seek as high a design speed as reasonable with the aim to reduce travel time. Practical design requires that levels of service should not be taken as absolutes but rather be viewed as starting points. Each project should be viewed as an investment and as such requires an understanding of the marginal returns to be realized. As in any financial situation, there is always a point of diminishing returns, i.e., greater investment will have no or little effect on increasing the return. The system-based evaluation of practical design in this study examined the safety and operational performance of various cross-section alternatives, based on highway capacity and highway safety manual procedures. The various alternative cross sections ranged from an improved two-lane section representing a practical solution approach to a four-lane-divided highway. A case study of a Kentucky intersection improvement project is presented that exemplifies a practical solution in practice.