Application of risk, cost–benefit and acceptability analyses to identify the most appropriate geosynthetic solution to mitigate sinkhole damage on roads

Sinkholes in karst areas disrupt transportation route serviceability causing significant direct and indirect economic losses and may lead to accidents involving fatalities. A quantitative procedure has been developed to identify the most suitable mitigation designs for a road recently built in an area with a very high probability of sinkhole occurrence. Installation of geogrids with different resistances to a variable number of road sections has been simulated taking into account the occurrence probability of sinkholes with different diameters in each section. The proposed methodology includes the following phases: (1) Development of a sinkhole hazard model that predicts the occurrence probability of sinkholes with different diameters in each 5 × 5 m pixel of the road. (2) Vulnerability appraisal of the road by means of stability analyses. (3) Risk assessment for the “without geogrid” and multiple “with geogrid” scenarios including direct and indirect economic losses, as well as expected number of fatalities. (4) Cost–benefit analysis to estimate the net benefit of the mitigation designs. (5) Acceptability analysis considering geogrid solutions based on cost-effectiveness, conventional (maximum acceptable rate of fatalities) and utility-based (maximum acceptable investment in mitigation to prevent fatalities) criteria. (6) Sensitivity analysis to evaluate the impact of the uncertainty of a set of parameters on the most critical results from the risk management perspective. The presented method could be easily adapted to other geohazards (e.g. shallow landslides, rock-falls, piping), different infrastructures (e.g. railways), as well as to other corrective measures (e.g. concrete slabs, catch fences, armoured roofs, steel meshes, barrier systems).

► The most suitable measure to mitigate sinkholes in a road has been identified.
► The hazard model produced include the sinkhole magnitude-frequency relationship.
► Cost-benefit and acceptability analyses have defined the mitigation measure design.
► The presented methodology could be adapted to other geohazards.