Implementation of Transition Curves in Vertical Alignment of Roads

Curves are used in the vertical alignment of roads to soften changes present on the grades. These curves are second order parabolas as they have been determined adequate. However, this can be improved. Therefore, the intention is to venture in the use of transition curves looking for improvements on the alignment that provide benefits to users, and provide the road with increased sight distance, smoothness and comfort. The mathematical formulation that defines the transition, before and after the traditional parabolic curve, is presented in a concise manner identifying its geometric elements, and with applications to a real design case that shows the advantages, and also the possible inadequate uses, of these types of curves. It is determined that transitioned vertical curves generally improve sight distance and, therefore, the safety of users, depending on site characteristics such as topography, grade changes, intertangency, and type of vertical curve. Nevertheless, care must be taken because complications may arise during the design and construction stages and this will eventually reduce sight distance and safety conditions due to inadequate designs by aesthetics, appearance and lack of continuity in the curvature. This paper opens doors for new research. To be able to make new contributions to the development of the geometric design of roads, it is necessary to go deeper and make computer animated models that include the dynamics of vehicles when traveling on the road designed.