Well-designed roadways should equally consider and address safety, mobility, and community needs. The concept of context sensitive design is an emerging project development and geometric design approach that aims to meet the objectives of these elements. Central to the design process is the selection of key design elements that have the potential to influence design choices and roadway elements. Design speed is probably the most influential factor and current practices on how this speed is selected and used may need to be revisited. The need to design a roadway that could provide all required clues to the driver in order to drive at desired operating speeds is also an issue that requires attention. Design consistency along with compatibility between design and operating speed feature prominent among the issues that should be considered within the context sensitive design. This paper focuses on various design elements and discusses their relevance, importance, and influence on context sensitive design.

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 le...

The objective of this paper is to develop a generic mathematical methodology that can carry out the available sight distance calculation of a roadway directly in 3-D space and in a fully automatic manner. The presented methodology overcomes the conventional approach of studying the 3-D road configuration separately and sequentially in its horizontal and vertical alignment. As far as the road surface is concerned, it is modeled as a 3-D B-spline surface. Moreover, the road centerline as well as the right and left borderlines which play a crucial role in the sight distance calculation are mathematically defined by modeling them as 3-D B-spline curves; therefore, their mathematical formulation is well determined. In addition, the cut and fill slopes of the road are also modeled as 3-D surfaces, and finally, the road surface and its corresponding cross sections are realized as one strictly defined and unified 3-D mathematical surface. This is particularly important since integrated 3-D geometric information is obtained, meaning that all calculations are applied in the real 3-D space where the road construction actually exists. Eventually, all the concepts that are incorporated in the respective equations and formulas are applied in the natural 3-D geometry of the road surface. The main competitive advantages of this methodological approach compared to other 3-D models proposed, is that the whole 3-D geometric information of the road construction is taken into account, and additionally, the available sight distance can be calculated for any potential trajectory followed by a vehicle. In addition, the methodology allows for universal adjustment that is not constricted by regional idiosyncrasies (i.e., existing design guides and policies). Finally, the computational part of this methodology is attained by expressing the functions in code through the programming language offered by the software Mathematica, whereas the whole process is demonstrated as a case study. It is noted that all the algorithms and codes appear in a fully automatic manner and parametric form, allowing the user each time, to set the corresponding and required input values to the algorithm.

Context Sensitive Solutions (CSS) provides a systematic and comprehensive approach to project development from inception and planning through operations and maintenance. The ability to categorize and measure the benefits of CSS projects is vital to the long-term success of this approach. The paper presents a framework for transportation officials and professionals that allows for the comprehensive quantification of benefits resulting from CSS through all phases of project development. A fundamental aspect of this framework is the identification of CSS action principles and their potential benefits. A matrix that correlates benefits to specific CSS principles was generated to allow for the development of appropriate metric indicators for each benefit. Guidelines for benefit analysis have been developed to provide transportation agencies with a set of recommended practices for assessing benefits. The guidelines emphasize the fact that CSS is a principle-driven, benefit-justified effort that can enhance an agency's goals and interaction with stakeholders and the public. The need exists to analyze and measure the benefits of CSS and its impact on projects (e.g. cost and delay) in order to demonstrate a best use of agency resources.