Road networking using remote sensing and GIS technologies - A case study

The alignment of the road in the past was generally practiced using conventional methods. Alignment in a hilly terrain prone to natural calamities is a herculeon task. With the advent of new technologies like Remote Sensing and GIS this is made much easier. The study area is situated along the Solang- Dhundi highway in Himachal Pradesh, India, which is about 12 kms from Manali. The existing road, is not as per the recommendations of the Indian Road Congress (IRC). The aim of study is detailing all terrain related features drawn from topo sheets, avalanche prone areas, use remote sensing, GIS and suggest an alternate route based on above findings in consonance with IRC recommendations. The methodology involves utilization of Raster to Vector (R2V) conversion software, AutoCAD Land Development software (ALDS), Arc View (GIS packages), ERDAS (Remote Sensing package) to create an integrated database and suggest the most feasible route. Scanning was carried out for all the three topo sheets at 1:5000 scale. Saved raster image is subsequently digitized for contours, drainage lines, road and vegetation using R2V software. Thus raster images are converted into vector images in the format of x and y coordinates. A mosaic was prepared using all the three digitized toposheets with the help of ALDS. Avalanche sites were demarcated and digitized using R2V. Calculation of slope and aspect were utilized to demarcate different zones of avalanche prone sites. The flow parameters calculated from certain standard formulae helped to know the direction of avalanche movement. DTM was generated using Arc/View and IRS-LISS III and PAN merged scene was superimposed to represent a real view of the terrain. Adjoining the Solang Dhundi track there are two major avalanche sites and a number of minor avalanche sites. One of the major avalanche site is centered around Pindri Nala. The observations obtained from flow parameters along the other major avalanche site close to an existing bridge site were studied to suggest either an alternate location of the bridge or provision of control structures. Thus the usefulness of these techniques is proved to suggest an alignment, which is less prone to avalanche.