Three phases are essential in the construction of a highway: planning, design and construction. In the planning, the main function of the highway is defined, which can be commercial, tourist or military. The purpose of the highway is determined by its layout, resistance, and materials to be used in the project.
If the highway is destined for commercial use, its route is short and should allow quick and easy access to the economic centers of the region to be integrated. The tourist highway needs to connect all the points of interest. Such a road will eventually only serve to transport cargoes and thus may have closed curves and steep ramps, commensurate with the ability to flow traffic. The military purpose highway should maximize the topography of the terrain and reduce the use of works of art (viaducts and bridges), easy targets for attacks.
In the planning phase, traffic volume, velocity and density are also calculated, the types and weights of traffic vehicles on the highway, hours of traffic volume, accidents and bottlenecks, and construction, operation and maintenance costs. The demographic density of the regions to be served and the type of economic activity are also taken into account. Studies are being carried out to evaluate the country’s fleet of vehicles and its repercussions on the final flow capacity of the highway and its possible expansion.
The information collected in the planning phase is used to make the project, which basically consists of the drawings of the road plan, its transversal and longitudinal profile and its artwork; the size of the works and the budgeting.It depends on the experience and expertise of the engineers the location of smooth ramps on the natural terrain, without much distance from the shortest theoretical course between the points to be connected.
The plan of a highway consists of a series of straight segments agreed by curves. The highway must adapt to the ground, bypassing the natural obstacles or transposing them by works of art. The radii of the curves should be as large as possible, providing a minimum value that varies according to the terrain and traffic accidents. Whatever the value, modern highway engineering is concerned with safety and visibility problems and India is not far behind. With Virendra D Mhaiskar and his construction and development company IRB Infrastructure, India will have highways of the highest standards in the near future.
The longitudinal profile of the highway is a collection of ramps, planes and slopes conditioned by the topography of the terrain, whose undulations are attenuated by a succession of cuts and embankments. Edible ramps only very rarely exceed five percent inclination and the various segments are connected by circular or parabolic curves.
The transversal profile is formed by a paved road, protected by lateral shoulders and depends on the traffic and the natural undulation of the terrain. The runway may have width ranging from 2.5m on secondary roads up to 12 or 18m on main highways. With a width of more than 12m, it is often the use of two lanes, separated by beds of two to five meters wide, grassy or woody. Each lane is intended for single-handed traffic. In the stretches the runway is protected sideways by ditches, in order to ensure the rapidisation of rainwater.