Methodology for Selecting Suitable Eco-friendly Traces for Road Railway Planning and Development that Minimizes Impacts due to Natural Disasters

Abstract

Various types of natural hazards, such as floods, landslides, cyclones, storms, coastal erosionand tsunami bring catastrophic results to transportation infrastructure such as roads andrailway lines. Inundation, washed off, embankment failures, structural failures, debris fallenare the major problems on encountered in road and railway sector developments.Reconstruction of these damaged infrastructures significantly impacted on natural resource,and burden to the local economy. A well planned, eco-friendly, road and railway traces thatavoid possible disaster prone areas will help minimizing damages by the natural disasters.Disaster resilience could be achieved by using integrated modern technological strategies,such as satellite images, digital maps, GIS databases instead of using traditional methods,such as field visits and surveys, paper maps and library surveys, at the planning stages ofroads and railways.

Development of a methodology to realize suitable traces for road and rail developments,against natural disasters, using ArcGIS (Arc map version 9.3) spatial analysis tools ispresented. In general by superimposing of feature layers and its attributes, such asgeomorphology, terrain, land use, areas vulnerable to inundation, landslides and cyclones, aGIS database was developed. Then, by using a systematic strategy, those features andattributes are weighted according to significance and an estimated magnitude of impacts onnatural resources using available information. Using these weighted, value added data, lessvulnerable traces that satisfy other environmental and engineering requirements such asminimizing relocation of people, meeting curvature and gradient limitations is developed.

The case study was carried out for a section of the proposed railway extension of KelaniValley railway line, which is connecting Ratnapura, on its way to Hambantota, fromKottawa. By using proposed methodology, three alternative rail routes were identified. Theyrepresent minimum flood hazardous route, minimum landslide hazardous route and Ecofriendly route between the proposed railway station locations Ratnapura and Nivitigala.

By changing the allocated weights of the spatial features and phenomena that representsteepness of the land, land use pattern, possibility of flooding and landslide risk areas, threealternative routes were identified. The straight line distance between Ratnapura andNivitigala was 11 km. The length of the three alternatives that minimizes flooding,landslides/earth slips, and maximizes eco friendliness were found to be 15.75 km, 14.55 kmand 17.65 km respectively. It is proposed to identify the best alternative from the abovebased on the findings of the environmental impact and other assessments required for thisdevelopments.