Geometric Design

Geometric Design of Highways -refer to the visible dimensions of streets and highways. -Its main purpose is to provide safe, efficient, and economical movement of traffic.
Major areas of the design:
Locational design
Alignment design (includes design controls and criteria)
Cross-section design
Locational Design One of the most crucial and important parts of the design process of highways. The location procedure is an iterative process in which engineers, planners, economist, ecologist and sociologist help to select several approximate locations based on the information and data available, and narrow their selection with the help of further information. Naturally, the location selection process has to be done with utmost care, taking into consideration the cost and efficiency of the propose facility. The best route from the standpoint of user benefit and economy together with the socioeconomic and environmental impacts likely to be encountered are all taken into consideration. The study begins with a survey to determine the traffic needs of the area and the controlling factors within the general route corridor area, such as terrain and existing and/or potential facilities. The following information will usually be of interest on locational planning and design:
Land use, population distribution, and density
Geological structure of the region
Potential for future industrial, farm, residential, or recreational development.
Existing roads, streets, and highways serving the area
Photographs of controlling features
Photogrammetric maps of the area
In choosing the final alignment, several criteria are used. Some of the major criteria are the cost of the project, the cost to the user and nonusers, the environmental and social impacts created by the project, the short and long term impacts on various interest groups, and historical and archaeological impacts.
Design controls and criteria Vehicle and pedestrian characteristics, traffic volume and its