Municipal solid waste transfer station planning through vehicle routing problem-based scenario analysis

Collection, transfer and transport of municipal solid waste (MSW) is one of the most challenging tasks of local municipalities and occupies a significant portion of the municipal expenses. Appropriately planned transfer stations (TSs) can increase system performance and reduce costs. Therefore, this study aims to develop a spatial modelling approach for investigating the optimum siting and economic impacts of MSW TSs. A geographic information system-based land suitability analysis was conducted to identify potential TS sites followed by a scenario analysis to determine optimum TS sites and waste collection routes for various collection vehicle capacities through vehicle routing problem modelling. The approach was implemented in the southeastern region of İzmir where a new landfill is to be built to serve three district municipalities. The addition of a TS in the study area reduced the collection time and number of shifts by 9%. Similarly, collection with large vehicles decreased the collection time and number of shifts by 25% and 17%, respectively. However, the unit cost of the system increased from 17.52 to 18.60 US$ metric tonnes^-1 waste with the TS addition because of the additional costs of the TS. The results indicated that TS addition is not economically feasible in the study area because of the small collection vehicle fleet (eight collection vehicles), proximity of landfill to areas with high waste density and district level collection. On the other hand, TS addition resulted in lower fuel consumption which may help reduce fuel-induced air pollution.