Spatiotemporal Bi-objective Evaluation Method for Urban Bus Systems

Abstract:

The mismatching of supply and demand in bus systems in the space-time dimension leads to the waste of spatiotemporal resources as near-empty buses are still running according to schedules， especially during off-peak hours. In order to quantify the above problems， a bi-objective evaluation method was built upon the investigation of the interactions among passengers， buses， and road resources. The evaluation system consists of two indexes， the supply-demand matching index （SDMI） and the space-time occupancy index （STOI）. The SDMI quantifies the matching degree of travel demand and bus line capacity， while the STOI measures the per capita occupancy of spatiotemporal resources in bus operation. The calculation of the SDMI and STOI were based on the global positioning system （GPS） data and the integrated circuit （IC） card transaction data， etc. Finally， four bus lines with different characteristics in Shanghai were used for case study. Considering the actual distribution of the two indexes， the classification thresholds of the bi-objective evaluation system were identified according to the cumulative frequency curve of the SDMI and STOI. The proposed method can be further utilized in the evaluation of public transit infrastructures and the optimization of bus type selection and bus scheduling， etc.

Key words:traffic engineering;public transit performance;bi-objective evaluation;supply and demand matching;space-time resources occupancy