Revisiting the adequacy of the highway drainage system using the geographical information system-a case study of NH-717a, Kalimpong

Abstract

Adequate drainage is very important for maintaining the structural soundness and functional efficiency of a road. Pavement structure including sub-grade must be protected from any infiltration of water, otherwise over a time it may weaken the sub- grade by saturating it and cause distress in the pavement structure ultimately. This is why rapid dispersal of water from pavement and sub-grade is a basic consideration in road design. Also proper drainage diverts the water from pavement surface quickly and reduces the chance of skidding of vehicles. This thesis work deals with the drainage design which is based on the science of hydrology and hydraulics. Former deals with the road side drainage system while the letter deals with the QGIS application in drainage. In this study an attempt has been made for adequacy checking the existing and proposed drainage system in a live project. All have been done on the basis of field survey, GPS and topography survey. Detailed reconnaissance and inventory was also carried out along the project road corridor in order to collect relevant information of existing drainage structure. All data were collected from NHIDCL, PMU-Kalimpong, N.H-717A,Barbot to Kaffer (26.100 km to 40.000 km) and its surrounding area of road upto Right of Way (R.O.W) major part of which covered under Pemling and Kaffer forest of Kalimpong district. Existing drainage pattern is also studied briefly so that Hydrologic calculation can be done easily which is a very important step prior to the hydraulic design. Design of drain is based on methods suggested in IRC: SP: 42-2014. An Emphasis has been made within a time boundary to check the adequacy of proposed drainage structure in ongoing highway strengthening and widening project. Key Word: Q-GIS, Highway, Drainage, GIS