Drainage Analysis at Super Elevated Segments of a Motorway

Abstract

Highway system makes the crucial contribution to the economic development of any nation. Road network not only connects people but also provides access to the employment, social stability, health and educational services. Motorways are the cornerstone of the road network of any country and their maintenance is pivotal for carrying ever increasing vehicle volumes. The main objective of this research is to carry out detailed analysis of the pavement drainage facility provided at super elevated segment of a motorway to check the adequacy of drainage inlets and underground drainage lines (pipes). Data for present study were obtained from detailed design drawings including curve details, rainfall data and data on drainage structures. We determined pipe capacity, number and size of pipes and time required for removal of rain water from super elevated road surface. Rainfall intensity was compute using FAA (Federal Aviation Authority) method. For determining pipe sizes, Manning’s formula was adopted. The pipes’ sizes so calculated were utilized to perform analysis to check adequacy of designed pipes. Software based analysis was also performed using AutoCAD Civil 3D and Storm and Sanitary Analysis. Our analysis revealed that presently sub-surface drainage infrastructure is being designed with low factor of safety (one). Since sub-surface drainage infrastructure is not only difficult to maintain/ replace, but also very costly, therefore a minimum factor of safety between 3-4 is recommended.