Friday, February 10, 2012

Network Vulnerability in Large-Scale Transportation Networks

Transportation networks are the lifelines in times of peace and prosperity as well as during and post disasters.

From roads to bridges, and whether by land, air, or sea, and via different modes of transportation, such networks provide the connectivity for the movement of people, goods, and services.

When Professor Michael Taylor of the University of South Australia in Adelaide issued a call for papers for a special issue of the journal Transportation Research A on Network Vulnerability in Large-Scale Transport Networks, my co-author of the Fragile Networks book, Dr. Patrick Qiang, and I knew that, given the timeliness of this special issue, we hoped to make a contribution.

We are delighted that we have heard from Professor Taylor who has let us know that the special issue is now in production with the publisher of the journal, Elsevier.

The papers in the special issue are:

Jenelius, E and Matsson, L-G, Road network vulnerability analysis of area-covering disruptions: a grid-based approach with case study

Taylor, M A P and Susilawati, S, Remoteness and accessibility in the vulnerability analysis of regional road networks

Watling, D and Balijepalli, N, A method to assess demand growth vulnerability of travel times on road network links

Bell, M G H, Trozzi, V, Hosseinloo, S-H, Gentile, G and Fonzone, A, Time-dependent Hyperstar algorithm for robust vehicle navigation in time-dependent stochastic road networks

Qiang, Q and Nagurney, A, A bi-criteria indicator to assess supply chain network performance for critical needs under capacity and demand disruptions

Nagae, T, Fujihara, T and Asakura, Y, Anti-seismic reinforcement strategy for urban road networks

Snelder, M, Van Zuylen, H and Immers, B, A framework for robustness analysis of road networks for short term variations in supply

Knoop, V, Snelder, M, Van Zuylen, H J, and Hoogendoorn, S P, Link-level vulnerability indicators for real-world networks

According to Professor Taylor: These are all excellent papers and define the global interest in vulnerability analysis. The special issue should be of wide interest.

Our paper in this special issue focuses on critical needs product supply chains. Critical needs products are those products and supplies that are essential to human health and life. Examples include food, water, medicines, and vaccines. The demand for critical needs is always present and, hence, the disruption to the production, storage, transportation/distribution, and ultimate delivery of such products can result not only in discomfort and human suff ering but also in loss of life.

Critical needs supply chains also play a pivotal role during and post disasters during which severe disruptions can be expected to have occurred. Indeed, the past few decades have visibly demonstrated that disasters, whether natural or man-made, may severely damage infrastructure networks, such as transportation and logistical networks, may cause great loss to human life, and also may result in tremendous damage to a nation's economy.

In our paper, we develop a supply chain/logistics network model for critical needs in the case of disruptions. The objective is to minimize the total network costs, which are generalized costs that may include the monetary, risk, time, and social costs. The model assumes that disruptions may have an impact on both the network link capacities as well as on the product demands. Two diff erent cases of disruption scenarios are considered. In the first case, we assume that the impacts of the disruptions are mild and that the demands can
be met. In the second case, the demands cannot all be satis fied. For these two cases, we propose two individual performance indicators. We then construct a bi-criteria indicator to assess the supply chain network performance for critical needs. An algorithm is described which is applied to solve a spectrum of numerical examples in order to illustrate the new concepts.