Accident Hotspots in Southern Expressway of Sri Lanka: Interpolation Evaluation using GIS

In this study, the southern expressway, which is first and lengthiest E class highway (126 km) in Sri Lanka, was analysed for roadside accident incidences. The primary objective of paper to identify best-fit interpolation techniques hotspots' most distinctive causes vehicular crashes. details were collected from Police Headquarters consisting 966 accidents that took place during period 2015 2017. To hotspots, GIS-based such as Ordinary Kriging, Kernel Density Estimation (KDE), Inverse Distance Weighting (IDW), Nearest Neighbour Interpolation methods used. spatial outcome four compared based on standard Prediction Accuracy Index (PAI). analysis executed using QGIS GeoDa. Results PAI revealed an IDW KDE outperformed other two methods. left right lanes spotted with 11 20 respectively, indicate lane 50% more prone than lane. Notably, nearly 5% entire road stretch estimated accident-prone spots both lanes. Peak recorded afternoon evening hours, buses active vehicle type. Uncontrolled speeding reason accidents, while unsuccessful overtake accounted 20% highway. design modifications warning sign placements at appropriate places may be recommended countermeasures.