Highway design

The overall objective of the research conducted at Carleton University was to update the current geometric guidelines to accommodate the driver behaviour in a quantitative manner. This was accomplished through focusing on the road user as a main element in highway design in order to create a consistent geometric design. To realize this objective, an experiment was designed to collect driver behaviour data using a test vehicle equipped with various instruments. Thirty volunteers were recruited to drive the test vehicle on a test route. The driver behaviour data collected included vehicle path, steering angle, speed, and lateral and longitudinal accelerations on different road classifications. These data along with the geometric alignment of the highways traversed in the experiment formed a huge database. This database was used to evaluate driver behaviour and analyse the interaction between it and geometric design and safety. This research has provided significant recommendations to the design guidelines for updating the design of horizontal curves and evaluation of design consistency. Examples of the aspects of horizontal curve design covered in this research include determining desirable lengths of spiral curves, driver comfort thresholds on horizontal curves, and recommended values for deceleration and acceleration rates at the entrance and exits of the curve. This paper summarizes the data collection methodology and presents the main contributions of this research.

2010

Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. In recognition of these needs, the highway administrators of the American Association of State Highway and Transportation Officials initiated in 1962 an objective national highway research program employing modern scientific techniques. This program is supported on a continuing basis by funds from participating member states of the Association and it receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board of the National Academies was requested by the Association to administer the research program because of the Board's recognized objectivity and understanding of modern research practices. The Board is uniquely suited for this purpose as it maintains an extensive committee structure from which authorities on any highway transportation subject may be drawn; it possesses avenues of communications and cooperation with federal, state and local governmental agencies, universities, and industry; its relationship to the National Research Council is an insurance of objectivity; it maintains a full-time research correlation staff of specialists in highway transportation matters to bring the findings of research directly to those who are in a position to use them. The program is developed on the basis of research needs identified by chief administrators of the highway and transportation departments and by committees of AASHTO. Each year, specific areas of research needs to be included in the program are proposed to the National Research Council and the Board by the American Association of State Highway and Transportation Officials. Research projects to fulfill these needs are defined by the Board, and qualified research agencies are selected from those that have submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Research Council and the Transportation Research Board. The needs for highway research are many, and the National Cooperative Highway Research Program can make significant contributions to the solution of highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement rather than to substitute for or duplicate other highway research programs.

Functional Classification of Highways - (AASHTO, 2011) and Traffic and Highway Engineering (Garber and Hoel, 2009).

For a variable that affects speed, what is the range that is influential?

3rd International Symposium on Highway Geometric Design, Chicago (USA). , 2005

In general the relationships among geometric design, speed, driving dynamics and safety can be regarded today to a large extent as soundly solved, while the human being (the driver), if at all, is only indirectly considered, although more than 90% of all accident causes are attributed to human error or improper human behavior. To find out to what extent driver performance as part of the road traffic system is regarded as essential for effective road design, operation, and safety, twelve modern highway geometric design guidelines were studied. The results of the in-depth reviews are discussed, analyzed, compared and evaluated. It was found that most of the guidelines only regard directly or indirectly human behavioral modes by simple assessments, for example, about perception and reaction time, eye and obstacle height, recommendations for limiting values of design elements, fatigue considerations for tangents, qualitative advice for three-dimensional alignment and sight distance quan...

International Journal of Engineering Science Invention (IJESI) , 2019

This paper investigates the effect of highway horizontal and vertical alignments design on safety within the context of design provisions in the Design Manual for Roads and Bridges (DMRB) using the Stopping Sight Distance (SSD) and Braking Distance (BD) as safety indicators. The curve radius/superelevations and gradient were investigated. The losses in SSDs and BDs were evaluated as provisions for curve radius/superelevations and gradients beyond the minimum desired values in the manual are adopted in a design. These losses were evaluated for several design speed bands using available geometric design formula and Microsoft Excel Software. At one step and two design speed steps below minimum desired radius, the SSDs lost on average across various design speed band was 25% and 44% respectively while the BDs lost was 35.8% and 63.6% respectively. The loss in SSDs and BDs across design speed bands increased at an average rate of 2.2% and 2.9% as the gradient increases by one percent. The BD which is a component of the SSD showed higher values meaning they are very sensitive. The relationship between the design of the considered parameters and the losses in SSDs and BDs may help give the highway design engineer a measure of how a design parameter that must exceed the minimum desired limit within a section of the entire design is impacting on the safety of the design.