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Remote Sensing and GIS Technology in Road Networking
ABSTRACT The alignment of the road in avalanche prone hilly terrain is a herculean task keeping in view the difficult and inaccessible terrain. The introduction of Remote Sensing and GIS techniques has made this quiet easier. The study area is situated along Solang Dhundhi Highway in Himachal Pradesh, which is about 12 kms from Manali. The aim of the study is to suggest an alternate route in consonance with IRC recommendations. The methodology involves the utilization of GIS and Remote Sensing packages to create an integrated database and suggest a most feasible route. Scanning was carried out and the saved raster images were subsequently digitized for contours, drainage lines, road and vegetation using R2V software in different layers. A mosaic was prepared using all the three digitized vector images. Avalanche sites were demarcated based on some preexisting knowledge. The flow parameters calculated from standard formulae helped to know the direction of avalanche movement.DEM was generated using ERDAS and IRS-LISS-III of latest date was superimposed over DEM representing a real view of the terrain. The slope and aspect map was generated using Arc/View. The road level is kept at a minimum elevation of 5 m from the HFL of river Beas.A Bridge with a span 58 m is proposed to connect Dhundhi to the rest of the road. The Data Elevation model (DEM) and slope map generated using Remote Sensing and GIS techniques helped in the identification of the elevation differences from Solang to Dhundhi and in knowing about the slope variations along the study area. Demarcation of the avalanche sites has further helped in knowing the direction of avalanche movement and thus information is utilized to align the road, which is less prone to avalanches. INTRODUCTION M.R Wigan in 1992 discovered that Image Processing techniques can successfully be used in road problems. The road texture characteristics, defect classification, automatic classification of speed and shape classification, vehicle number recognition are the various problems which can be addressed. Chester G.Wilmot et. al in 1998 applied Remote Sensing successfully to the traffic study. Through Remote Sensing the vehicle counts could be made with the help of various vehicle emissions. It has been observed that the observations taken by Remote Sensing on two-way two-lane roads are 800/hour which is approximately 80% of the observations made on one lane roads. Volume, Directional split (Percentage of traffic in the dominant direction), and traffic composition are the factors affecting the observations. David K.Loukes and John McLaughlin were the pioneer Canadians in the field of GIS applications to transportation using various thematic data. The GIS offered the capability of linking graphic entities (discrete points, roadway links, right of way parcels, etc) to many existing attribute data base that contain information about the transportation infrastructure. The linkage mechanism is enabled through the use of carefully chosen location keys. The resultant product would be suitable as a base of subsequent GIS-T applications. NECESSITY OF STUDY Lahul and Spiti remains snow bound and gets cut off from the rest of the country during the winter seasons. The only approach to this area is through Rohtang Pass which is also inaccessible during the winter months .Thus, to connect Lahul and Spiti to the rest of the country, a track from Solang to Dhundhi is proposed.Dhundhi is also important from tourist point of view. The track is proposed taking into considerations the past developments and the future prospects. Keeping in view the strategic position of the proposed track, a study was undertaken using integrated approaches such as Remote Sensing and GIS. LOCATION OF THE STUDY AREA The study area falls in Distt. Kulu of Himachal Pradesh.Kulu district covers an area of 5435 sq.kms in the central part of Himachal Pradesh. It is bordered by the districts of Lahul and Spiti in the south and north east, Kangra in the north-west, Simla in the south and Mandi in the east.Kulu can be approached by Chandigarh-Bilaspur-Mandi-Kulu highway (NH 21) or by Pathankot-Mandi -Kulu highway.The district of Kulu forms a transitional zone between the greater and the lesser Himalayas and presents a typical rugged mountaineous terrain with moderate to high relief. The altitudes vary from 1300m to 6000m. The rivers that drain the area are Beas and its distributary Parbati, the former originates from Beas Rikhi near Rohtang Jot and the latter from Prabati glacier near Pin Parbati Pass. The rock types found in the district are phylli, slate, quartzite limestone, schists and granites and have been classified on the basis of the physical characteristics and mode and period of formation. The Kulu valley is a structurally and lithologically controlled landscape sculpted by the glacial and glaciofluvial processes in the inner part of Himachal Lesser Himalaya. In the north west the valley contains some glaciers in the high altitude of its upper catchment.The Beas is the main river which flows through the valley. The Beas river has a gross channel slope of 36.72m/km between Rohtang pass and Hansu whereas its mean channel slope is 15.13m/km. The Kulu valley has a temperate climate that gets cooler towards the north. The mean maximum and minimum temperature of the valley is about 24°and 7 °respectively. The rainfall in the valley is moderate with large annual fluctuations. The track is 7kms and lies between Solang and Dhundhi .Solang station situated at 770 09' 27" E longitude and 320 19' 27" N latitude is located 12kms from Manali.It lies at an altitude of 2480m above M.S.L. This station receives a good snowfall and on an average builds up more than 2m of standing snow and is on the windward side of Pir Panjal Range.Forested, the station is alongside, Beas river flows in the north-south direction, which is a tributary of Beas sub-basin. Dhundhi is situated at an elevation of 3050m above M.S.L and is located on the south of Pir Panjal ranges, 14kms north of Bhang, between Solang and Beas Kund in Himachal Pradesh. Dhundhi is characterized by heavy precipitation and cumulative winter snowfall exceeds 11m.  A mosaic of 3 toposheets at 1:5,000 scale ROAD NETWORKING The location of a highway route requires the consideration of many factors and often balancing of conflicting features. The goal is to obtain a route at a minimum cost, with minimum disturbance to the natural terrain and cultural features requiring least maintenance. The process of selecting a route is established in four steps:
Numerous methods have been used for road network determination. Aerial photography is one of the oldest methods used. Through aerial photography, topographic maps and images are prepared and interpreted for the route detection. Image interpretation techniques have proved to be of great value in each of the steps as the survey progresses from reconnaissance of the area to the final stage staking on the ground. Colour photography is used for the detailed analysis of certain routes. Satellite imageries and high altitude photography is a good source as far as regional evaluation of routes are concerned. Such imageries can also be used to develop the base maps for presentation of the possible alternatives. Computer techniques are being used since recent times and their applications are used to determine the earth quantities by photogrammetric methods for designing a road, comparing costs of alternative alignments and for determining final pay quantities during the construction of a road. Digitized data has been used for large scale road network.Khorram (1982) studied the potential residential suitability of wildland area in North California by integrating various kinds of information including the accessibility map. The map was produced by digitizing the road network and registering the data within a geobased formation system compatible with other data types used in this study. REMOTE SENSING Remote Sensing contributes most significantly to highway engineering during the reconnaissance and feasibility stage of route planning when general information is to be analyzed about large areas of terrain, rather than specific information about a small area, as would be required for example for the final alignment . Aerial photographs are one of the most popular Remote Sensing techniques owing to their supporting small scale as well as large scale surveys. Aerial photography has also been used to produce contoured topographic maps. Satellite imagery and landsat may also provide the source of Remote Sensing imagery. The scale of Landsat and IRS are ideal for reconnaissance surveys and can be appropriate for preliminary interpretation as a part of more detailed surveys. At reconnaissance and feasibility levels of survey individual geotechnical aspects of road construction are subordinate to the main aim which is to identify a route corridor. The reconnaissance or pre feasibility study helps to examine the entire area lying between the end points of a road and to identify route corridors within it. It would help to establish the relief and geology of an area, the main soil types, climatic and hydrological conditions. Remote Sensing in the form of photographic, scanning and processing systems is one of the most appropriate means of recording ground conditions and assessing their potential for engineering projects land also to evaluating the effects of subsequent construction on the environment. Remote sensing is only an aid to engineering investigations providing information which is complementary to field measurements /site visits and existing sources of data such as maps and project reports. GEOGRAPHICAL INFORMATION SYSTEMS Parker (1998) States that GIS is an information technology which stores, analysis and displays both spatial as well as non spatial data. Eg. the contours are the lines having equal elevation. The contours are the spatial data and the z values associated with them are the non-spatial data. The growing would population is putting a pressure for the demand of the earth's resources and the need is to organize the resources so that they may be utilized impartially by all forms of life. This not only requires an understanding of the spatial and temporal patterns of resources but also insight into spatial and temporal processes governing their availability. The spatial data and its analysis are required by a number of agencies. A civil engineer would need it for routing canals and roads and estimating the construction costs. The maps are the cheapest mode for representation of data. The information collected is very easily represented on a piece of paper. Storing the information on the map is a cheap alternative although the compilation of data, drawing printing and publication is a costly and a time consuming affair. More recently, the aerial photograph and satellite images have made it possible to see how landscapes change over time to follow the relentless march of desertification or erosion or swifter progress of forest fires, floods, locust swarms of weather systems. The products of airborne and space sensors are photographic images or streams of data on magnetic maps. The digital data are coded in picture elements-pixels cells in two dimensional matrix. The growing demand for more spatial data and for better means to analyze them can only be met by using computers. AVALANCHE DYNAMICS Avalanches are falling masses of snow that can contain rocks, soil or ice. The major industries affected by avalanches are: Transportation: Avalanches cause interruption of movement on (and placement of) highways and railways in mutations corridors. Companies and governments incur the costs of snow removal and distances carried to human life and infrastructure. Construction: Avalanche destroys buildings and kills or injures residents. Engineers must make informed decisions regarding the placement, design and protection of facilities and operations in avalanche prone mountainous terrain. The facilities needing protection include houses, mines, and telephone and electric transmission towers. Tourism: In mountainous recreational areas, avalanches can cause deaths, injuries, bad reputations from lawsuits, restriction to services or selection of alternate routes. The greatest hazard avalanche can cause in people traveling in avalanche prone terrain is anxiety. Zone Planning Using Swiss Guideline According to the Swiss guidelines an avalanche track is divided into three different zones viz the starting zone, the middle track the runout zone. The demarcation is done such that the tracks with a slope between 30º -50º fall in formation zone, the tracks with a slope between 12º -30º fall in the middle track and the tracks with a slope less that 12º fall in the runout zone. The main assumption of this model is that the flow is to be uniform.  Avalanche site (Pindri Nala) METHODOLOGY The methodology pertaining to database preparation for the Solang Dhundhi track was done with the aid of GIS and Remote Sensing packages. The first step in the database preparation was the scanning of the topo sheets, which are at a scale of 1:5000. The scanned toposheets were registered with a common frame of reference using R2V (Raster to Vector conversion software). The registered topo sheets were digitized for contours, drainage patterns, river network and other details using the inbuilt tools in R2V conversion software. The raster images were thus converted to images in the X and Y coordinates. The vector images scattered in three toposheets were exported one by one in AutoCAD land Development Software (ALDS) and they were edge matched using inbuilt tools in ALDS.The database was prepared and validated using various facilities provided in Arc/View. The Data Elevation Model (DEM), slope and aspect maps generated using ERDAS Imagine software represented using real view of the terrain. Finally, the road was aligned using the recommendations given by IRC using AutoCAD Land Development Software. RESULTS AND DISCUSSION Solang (2480m) above M.S.L and Dhundhi (3050m) above M.S.L falls in Distt. Kullu.The track from Solang to Dhundhi is important keeping in view the growth in the past few years and the tentative future developments to take place.Dhundhi valley is also a major attraction from the tourist point of view.Keeping all these factors in view; a track from Solang to Dhundhi has been proposed. The existing track (data obtained from GPS survey) was studied and found it not as per the recommendations of the IRC. The new route proposed has been aligned using the gradient criteria as suggested by IRC. The gradient is the foremost consideration while aligning a road in the hilly terrain. Very steep gradients are avoided as it is not only difficult to climb the grade but the vehicle operation cost is also increased. The Solang Dhundhi track has been aligned with a ruling gradient of 1:16.67 as suggested by IRC. The length of the road for every 5m gain of height is kept between 83.5 m to 92 m approx. A length more than 92 m would incur unnecessary expenditure for the road length. The strategy adopted while aligning the road is to go along the contour for a min.length of 83.5 m and rise as soon as the desired length is achieved. A minimum elevation difference of 5 m has been maintained between the road level and the HFL of River Beas to avoid any flooding conditions. At places where this is not feasible and the road and river lie on the same contour, a minimum of 50m horizontal distance is maintained between the road and the river level. Hair pin bends (five in number) have been provided at places where there is a deep ascend to obligatory points. A bridge of span 58m has been proposed at an elevation of across the Beas Kund Nala to connect Dhundhi thach to the rest of the road. The details pertaining to the road are as follows.
 IRC 1C LISS III Date 25th August'2000 (Photograph showing the study area) ACKNOWLEDGEMENT I am highly obliged to Dr.L. N. Sharma, Lecturer, Applied Sciences Department, Punjab Engineering College, Chandigarh, for his expert guidance, valuable criticism and encouragement without which this project would not have been completed successfully.. Special thanks are due to Col. P. Mathur, Deputy Director and Mr. Amod Kumar, Scientist 'D' Avalanche Study Establishment (SASE), DRDO under Ministry of Defence for their invaluable guidance throughout the work. Last but not the least, I thank almighty who gave me courage and perseverance to accomplish this honorous task. REFERENCES
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