Description
Abstract: Transportation is one of the urban critical infrastructures, and our dependence on it persists as cities sprawl. Interconnection favoring mobility is where local policy efforts continue, whereas its impact on resilience is poorly understood. There are growing concerns about the resilience of transportation systems to the threat of climate disasters and social unrest. Current research on public transport resilience focuses on single-modal public transportation networks (PTNs) or simple aggregations of multiple networks through transport complexes. To gain a comprehensive understanding of multimodal public transportation networks (MPTNs), a systematic approach is needed to consider network interconnections in a geospatial manner. From a topological perspective, MPTN may behave differently compared to single-mode PTN. To explore how it topologically affects network resilience, this research adopts a real case study in Hong Kong and reveals the advantages of MPTN.The study models six modes of PTNs in Space-L representation, including metro, light rail, franchised bus, public light bus, ferry, and tram, and there are a total of 8,644 nodes and 15,551 edges. The MPTN is created subject to proximity, and the haversine distance between nodes is computed to determine where to add additional intermodal edges. In the proximity analysis, the distance limit to identify intermodal edges is considered a variable, which may vary among cities and nations. Therefore, we analyze a group of MPTNs created with distance limits from 0 to 1,600 meters and select 100 meters to show detailed results, as 100 meters is roughly the average size of public transport interchange sites in Hong Kong.
The six PTNs are integrated network-by-network in the analysis, and we observe the change in network characteristics and resilience-related indicators, such as network efficiency, geospatial efficiency, preparedness indicator (node homogeneity), robustness indicator, and network interoperability (passenger relocation capability). Specifically, we introduce a null model as the benchmark for network properties like robustness that heavily depends on network size and the number of edges. The null model integrates the Erdos-Renyi model with additional geospatial constraints (controlling edge lengths following the discrete distribution in the original network) to avoid arbitrarily added long edges.
Results display that the MPTN has prominent topological advantages in efficiency and resilience-related indicators. Node homogeneity increases significantly, indicating better preparedness as the vulnerabilities are more distributed across the network. In terms of robustness, MPTN interestingly outperforms the benchmark, especially when facing degree-based attacks, and it exhibits high fault tolerance to minor disturbances, which is not observed in the individual PTNs. Moreover, the distance limit analysis provides evidence that, for real-world applications, enhancing intermodal transfer brings significant marginal benefits at a short distance, and the cost is relatively low. Additionally, real-world MPTN has better efficiency and geospatial efficiency than the null model in this research.
Generally, the proposed real-world case study from Hong Kong investigates the topological impact of system interconnection in the public transportation sector and provides evidence of the potential advantages. Planners can consider enhancing the intermodal transfer instead of building another new system to sustainably improve the resilience of existing systems.
| Period | 15 Jun 2023 |
|---|---|
| Event title | 30th International Symposium on Sustainable Systems and Technology (ISSST 2023) |
| Event type | Conference |
| Location | Fort Collins, United States, ColoradoShow on map |
| Degree of Recognition | International |