Author: Dr. Jean-Paul Rodrigue
Natural and anthropogenic disasters have disruptive effects on transportation systems, impacting modes, terminals, and infrastructure.
1. Transportation and National Security
There is often more to learn from failure than success, even if failure is never welcomed. While the factors behind success can, at times, be ambiguous, the reasons for failure are commonly quite clear. The reasons why an airline is having a profitable quarter are more difficult to assess than if one of its planes was to fall off the sky.
Transportation systems are designed to operate under defined conditions. Yet, disruptions such as those caused by accident or by a storm are rather frequent and well mitigated. On occasion, a disruption at a much larger scale takes place to the extent that the safety or security of a whole region or nation is compromised.
A disaster involves extensive damage to people and physical infrastructure that is unforeseen in nature, scale, and extent. It often implies that their risk of occurrence has not been properly assessed, and a large share of the damage is the outcome of a lack of preparedness.
While what could be defined as an emergency can be handled by local resources such as local police, healthcare, and emergency response, a disaster requires a broader intervention that could go to the national and even international level. A disaster is an event going beyond anticipated capabilities to respond.
Transportation is often considered a critical infrastructure since a disruption in one of its components can significantly impact the economic and social well-being of a region or a nation. An effective way to assess how critical infrastructure is would be to consider the impacts its removal would have on the flows and activities it services. From an economic standpoint, the impacts of disasters are dependent on three factors; 1) the nature and level of incidence of disasters; 2) the level of exposure of populations and infrastructures, and; 3) the level of vulnerability of populations and infrastructures. Several drivers have an impact on the threats and risk level of disasters on transportation systems:
- Increased mobility. The mobility of passengers (for commuting, tourism, business, and migration) and freight has risen globally, including the crossing of international boundaries. Air and maritime transportation are particularly illustrative since their growth implies more vehicles and cargo in circulation. This trend has also been strengthened by trade agreements and reductions in tariffs promoted by organizations such as the World Trade Organization. There are more economic opportunities, but some risks, such as infectious diseases, can spread faster and more extensively.
- Infrastructure and economic interdependency. Transportation and energy infrastructures are particularly interdependent, implying that a disruption in one infrastructure may spread to other infrastructures. This interdependency is also economic as trade is based upon respective specialization. Some parts and components are provided by a limited number of suppliers, which can be prone to risks in case of disruptions. In several sectors, supply chains are relatively rigid, implying that there are limited options for substitution. The same applies to resources such as oil that require a continuous supply with limited margins to accommodate major disruptions.
- Centralization and concentration of distribution. The principle of economies of scale often leads to a centralization of network structures and a concentration of economic activities. Most transportation systems are organized as hub-and-spoke networks, particularly for air transportation, but this characteristic is also prevalent in maritime shipping. Global trade is articulated by major gateways where a few control a large share of the commercial flows. At the more basic geographical level, strategic passages impose bottlenecks for global maritime freight circulation.
- Urbanization. The emergence of large cities has led to acute concentrations of populations, a pattern significantly different than the more dispersed settlements that prevailed in rural societies. The concentration of the population equates with a concentration of risk. Thus, any disaster affecting an urban area is compounding its impacts on par with the population and infrastructure density. It is also worth underlining that many of the world’s largest cities are located in coastal areas, exposing them to an additional array of risks linked with hurricanes and storm surges.
The transport industry has responded to these drivers with massive investments in infrastructure and facilities that have expanded the capacity and efficiency of transportation systems, both at the domestic and international levels. In turn, added flows and capacities increased demands on the management of physical distribution systems, including transportation, transshipment, warehousing, insurance, and retailing. They are of strategic importance to national economies. Due to their scale and connectivity, the following transportation networks are particularly vulnerable:
- Air transportation. Such networks are vulnerable to disruptions at major hubs, while disruptions at smaller hubs will have limited consequences.
- Maritime shipping. The vulnerability of maritime networks has different considerations depending on if the node is a hub or a gateway. Disruptions at a hub will mostly impact maritime shipping networks, while disruptions at a gateway will mostly impact the hinterland.
- Logistical networks. Vulnerable to disruptions impacting one element of the supply chain and the connected activities that are upstream and downstream.
- Road networks. Because of their mesh structure, road networks are not highly vulnerable to disruptions, unless this disruption is at a wide scale.
- Rail networks. While linear rail networks are vulnerable to disruptions, complex rail and transit networks have a mesh-like structure, making them more resilient.
- Power grids. They are usually highly redundant but are subject to a hierarchical vulnerability where the higher up in the hierarchy, the more extensive the disruption.
With the increasing reliance on distribution systems, any failure of transportation, due to intentional or non-intentional causes, can have very disruptive consequences and can compromise national security over four major issues:
- Transportation supply. Ensuring that transportation modes, routes, terminals, and information systems can satisfy national security needs such as troop deployment and emergency relief.
- Transportation readiness. Maintaining the readiness of transportation to face time-sensitive national security needs.
- Transportation vulnerability. Reducing the vulnerability of the transportation modes, terminals, and users to intentional harm, accidents, or disruption from natural events.
- Illegal use of transportation. Reducing the trade of restricted or illegal goods (e.g. drugs, endangered species), and illegal immigration.
2. Potential Threats and Risks
The disruptions caused by disasters take place over complex transportation systems and are consequently difficult to evaluate. Particularly, the non-linearity character of complex systems implies that disruption can have multiplying and feedback effects, many unforeseen. A disaster of high severity is likely to trigger a phase transition where the resulting transport conditions are very different from those ex-ante. The resilience of a transport system is its capability to resume operations at a level similar to that before a disruption occurred. The less disruption in terms of capacity and fluidity and the faster a system resumes its operations to a normal level, the higher its resilience. Resilience is highly influenced by the network structure, particularly its redundancy.
Resilience is also related to the nature of the disaster. A simple taxonomy reveals that they are natural or anthropogenic in origin.
a. Natural disasters
Natural disasters come into four main categories:
- Extreme weather events. Many weather events such as storms and blizzards occur regularly and tend to have minimal impacts on transport systems with delays, partial closures, or diversions. Others, such as floods, cyclones (hurricanes), tornadoes, and droughts, can be of disastrous proportions. Tropical cyclones are particularly harmful since they cover wide areas (a mid-sized cyclone can cover an area of 500 km in diameter), are moving slowly (25 km/hr), and are associated with high winds and rainfalls. There is a distinct seasonality to hurricanes with the highest frequency in the northern hemisphere between August and November, with peak activity during September. In the southern Pacific and Indian oceans (no hurricanes in the south Atlantic), the period between November and April shows the highest frequency of occurrences. During a hurricane event, regional air transport and public transit systems are usually shut down, and land transportation can be severely impaired. For instance, major floods in Thailand in 2011 were highly disruptive for the electronics sector, particularly hard drives, since it accounted for 25% of global production. Hurricane Sandy, which struck the New York / New Jersey coasts in 2012, incited the preemptive shutdown of all the airports, ports, and public transit systems of the region. Due to flooding and power outages, it took several days for the system to be brought back to normal operating conditions, which substantially impacted commuting. There are concerns that climate change may be linked with more recurrent extreme weather events. Beyond this debate, the fact remains that extreme weather events will continue to occur, but their frequency and scale is uncertain.
- Geophysical: Tectonic activity is the source of the most serious geophysical disasters. Earthquakes are salient forms of geophysical threats since they are difficult to predict but are focusing on areas in the vicinity to boundaries of tectonic plates. Tsunamis are also considered an emerging risk as a growing number of people live along coastal areas. The 2011 Tohoku earthquake in Japan is among the five largest in recorded history. While the damage by the earthquake was significant, it is the associated tsunamis that caused the most extensive damage to the Japanese transport infrastructure. Further, the earthquake had significant impacts on global supply chains as the Japanese automobile production fell by 50% in the following months, mostly because of disruptions in supply chains. Although areas of high earthquake occurrence are readily identified, the specific location and scale of an event remain a probability that is often difficult to conceptualize in transport infrastructure planning. While volcanoes have always been localized and easily identifiable risks, the ash clouds they release have recently been a source of concern. For instance, the ash cloud released by the 2010 eruption of the Eyjafjallajökull volcano in Iceland forced the shutdown of most of the European and transatlantic air transport system for close to a week, stranding millions of passengers. Since air transportation is an extremely recent phenomenon in geological times, the probability and extent of ash cloud events remain uncertain. For instance, an event of the scale of the Krakatau 1883 eruption taking place today would be of profound ramifications for the global maritime and air transport systems.
- Geomagnetic storms. They concern disturbances in the earth’s magnetic structure, mostly the outcome of solar activity, where the frequency of geomagnetic storms varies accordingly. Geomagnetic storms can impair power grids and have a higher probability of taking place around the north and south poles. Still, they are less known and often an underestimated risk. The largest geomagnetic storm in history took place in 1859 (called a Carrington Event in the name of the British astronomer who documented the flare). Still, since back then, electrical systems were rudimentary, its impacts on human activities were marginal. Such an event taking place today would be heavy in consequences (e.g. hundreds of millions losing electric power) and would qualify as a disaster.
- Sea level rise. Historically, sea levels, outside standard tides, have rarely been considered for human settlements, implying that many cities and infrastructure are built right above the upper tidal limit. Potential rises in sea levels attributed to anthropogenic causes (climate change) qualify as a natural disaster. There are various scenarios about potential sea level rises, but evidence underlines a rise by one meter by 2100 (compared to a 2000 baseline) as almost a certainty. If the sea-level rise accelerates, the one-meter scenario could even be reached by 2050. Irrespective of the timing, sea-level rise places critical transport infrastructure such as ports and airports at risk of damage and discontinuity in operations. For instance, a port terminal or an airport could not be directly impaired by sea-level rise, but its access roads could compromise its commercial viability. Sea level rise would also amplify the impacts of extreme weather events, namely storm surges.
b. Anthropogenic disasters
The second class of disasters concern those that are artificial, resulting from human activities, and can be intentional or unintentional:
- Accidents. The outcome of technical failures or human errors and where modes, infrastructure, or terminals can be damaged, even destroyed, which includes injuries, the loss of life, and property damage. Small scale accidents occur very frequently, particularly over road transportation systems. However, transportation-related accidents are rarely considered disasters because they are mostly very punctual events not related to a massive loss of life and damage. There are notable exceptions. An aircraft crash with a complete loss of life can be considered a disaster. Even if planes are larger and more people are flying, improved airline safety has made these events increasingly uncommon, particularly in terms of accidents per passenger-km flown. Industrial accidents related to the release of hazardous cargo (particularly fuel and chemicals) taking place in an urban area either during transport or at a transport terminal are also an issue of concern.
- Infrastructure failure. Transportation infrastructure can fail due to a lack of (or deferred) maintenance, improper management, design flaws, or handling more traffic than designed. Bridges and other similar structures are particularly vulnerable, especially from a system-wide perspective where aging (or poorly maintained) infrastructure can impact many components within a similar timeframe.
- Conflicts, terrorism, and piracy. Conflicts such as wars and civil unrest often damage infrastructure, with transportation commonly a voluntary or involuntary target. Due to the importance of global trade and the structure of maritime shipping networks, bottlenecks (strategic passages) are subject to the risk of partial or complete closure. Terrorism has been a disruptive issue that came at the forefront over the last two decades. For instance, the disruptions caused by September 11, 2001, events can be considered a disaster because of their scale and scope. More than 2,700 people were killed on the planes and the ground with the immediate response resulting in closing the North American air transport system. The surge in global trade in the second half of the 20th century created an environment where piracy became an issue. Shipping lines are forced to pass through constrained areas, chokepoints, namely straits such as Malacca and Bab el Mandab, along the heavily used Asia-Europe maritime routes, making the interception of ships more feasible within a delimited area. The outcome of piracy on global supply chains has been small but not negligible as ships have changed their routing, and that insurance surcharges are being levied for cargo transiting through areas prone to piracy.
- Economic and political shocks. They are likely to play a growing role in the future, particularly financial issues, as most developed nations have accumulated a staggering amount of debt that is likely to be defaulted on. Such an event would be associated with a lack of capital available for infrastructure construction, maintenance, and oversight, rendering elements of the transport system more prone to risks, such as accidents and infrastructure failure.
- Pandemics. At the intersection of natural (biological) and anthropogenic causes (people are vectors, and anthropogenic causes could mutate a virus), a pandemic is an event of potentially profound ramifications. Yet, the risk of the event itself is extremely difficult to assess. Although a pandemic would not directly damage transportation systems, transportation is intractably linked with such a disaster as it will act as a vector for its diffusion (particularly air transportation), and shutting down transportation services in the wake of a pandemic would compromise supply chains (food, energy, medical supplies). The COVID-19 pandemic of 2020 underlined how disruptive this biological and epidemiological event was on transportation systems (see Transportation and Pandemics).
As the freight transportation dimension is getting increasingly globalized and complex, supply chain risks are salient. Developing economies are particularly vulnerable to an array of disasters because infrastructure, including transportation, tends to be of lower quality and more poorly managed, and thus less resilient to disruptions. In addition to the risk, a fundamental element is who bears the responsibility for disruptions and their costs. Reconstruction and replacement costs of transportation modes and infrastructure can be substantial. International commercial transactions underline that the actor assuming the liability depends on the type of terms. Therefore, depending on the terms of the contract, the same event may imply a different liability allocation.
3. Transportation Disaster Planning
Although a potential disaster can never be effectively planned, and even anticipated in some instances, there are a series of steps, known as Disasters Risk Management, which could reduce disruptions:
- Risk Assessment. The likelihood of an event and its potential impacts should be comprehensively assessed, such as its probability (low to high) over a defined time frame and a specific area (e.g. a city or region). This should provide a prioritization of risks, but it remains a very uncertain process.
- Preparedness. In light of the potential risks, a level of preparedness should be considered in terms of potential responses. This can involve the warehousing and positioning of relief material, such as fuel, parts and equipment, and the training of the labor force in emergency situations.
- Mitigation. Concerns the immediate reaction to the event and can involve the shutting down of transport systems (particularly public transit), the evacuation of populations, and the mobilization of first response resources, namely distributing emergency relief (food, medical supplies). The goal is to control and attenuate the disruptions caused by the disaster.
- Response. Once the disaster has been mitigated, steps are implemented to bring back capacity with existing infrastructure. If a mode has been impaired, the usage of alternative modes and infrastructure has to be considered. The goal is to maintain operational as many elements of the transport system as possible.
- Recovery. Concerns all the steps necessary to recover the transport capacity that was lost during the disaster. It can involve repairs, the restarting of services that were discontinued as well as investments in new and improved infrastructures, modes, and terminals. The goal is to bring back the capacity and level of service to pre-disaster conditions. With the lessons learned from the disaster, more resilient infrastructure and networks are a likely outcome.
The reconstruction time of transportation infrastructure tends to be slower than other infrastructure. Evidence from the 1995 Kobe earthquake underlines that electric power and telecommunications are first restored in a matter of weeks. Road and rail infrastructure can take several months, while it can be a matter of years for port infrastructure. Transport infrastructure, particularly terminals, is much more capital intensive than utilities and requires specialized and heavy equipment for repair or construction. Highway and rail services can run at a lower capacity and on alternative routes. If a port is shut down, other ports can generally be used (the same applies to air travel). While this is less efficient as it involves longer routes for imports or exports, it remains, in most cases, economically feasible. However, recovery is contingent upon the availability of capital, equipment, and managerial expertise. Therefore, in advanced economies, recovery is much faster than in a developing economy.
This opens the door for public-private partnerships since the private sector has a vast array of resources, including transportation and warehousing assets, that can be brought in during a disaster. For instance, when a large-scale weather event is predicted, such as a snowstorm or even a hurricane, it is common that large retailers reposition the inventory of critical goods such as water and power generators to distribution centers and stores nearby the impacted area.
4. Transportation Resilience
One of the core aspects of mitigating transportation disasters concerns the resilience of transport systems, which is having infrastructures and modes able to withstand and recover from natural and anthropogenic hazards. Achieving a level of resilience implies a combination of redundancy or flexibility. Redundancy involves a level of duplication of assets, let them be paths to connect locations or additional inventory within supply chains. Flexibility concerns the capacity to find alternatives such as new routes, new terminals, or new suppliers.
a. Monitoring and assessment
In any unusual emergency, situational information is crucial. Those involved can develop their own solutions or alternatives, such as postponement, modal shift, or merely forfeiting a trip if it is discretionary. If properly informed, consumers and supply chain managers tend to act rationally, which may lessen additional disruptions, damage, and even injuries and the loss of life. Depending on the risk factors involved, it remains fundamental to monitor the situation and assess which parts of the system can be brought partially or wholly online as soon as possible. This, combined with accurate information releases, institutes public confidence that the crisis is well managed while conveying patience and goodwill from those impacted. Even the admittance that limited information is available can be useful as it conveys the message that a disaster has complex ramifications. However, transportation infrastructure operators can be unwilling to share information about the impacts of disruption on their capacity and operations since it can underline existing weaknesses and have competitiveness implications.
b. Support for the impacted population
This strategy applies mostly to passenger transportation. For commuting, there should be short-term alternatives than having to commute to a location that is now difficult to access. This can involve telecommuting strategies, the postponement of non-essential work tasks, or the setting of alternative work locations. Freight mobility is concerned to the extent that those impacted are likely to need basic supplies, shelter, and fuel.
For long-distance movements, particularly for intercontinental flights, there will be stranded passengers with no alternatives, at least in the short term, to head back home. Many may be facing financial difficulties as their travel was budgeted, accommodations paid in advance, and thus have limited means to cope with the additional costs involved. An alternative lodging market should be made available so that those with stretched means can opt for simpler accommodations, down to a cot provided for free in an airport terminal corridor.
c. Removal of discretionary demand
Disruptions, complete or partial, always result in much more transport demand than supply. This should imply a sharp rise in fares, leaving those willing to pay such a high price able to travel or having only the most critical freight being carried. However, since airfares or containership slots are booked in advance at a locked price, discretionary travel may remain even when the system is disrupted, particularly when the disruption is over. However, demand is still facing severe backlogs. Incentives should be provided to remove as much discretionary demand out of the system as possible while the disruption and its consequences last.
An effective strategy concerns creating a seat swapping market, particularly with the help of information technologies. For instance, an airline could contact ticket holders for specific flights and ask them if they could purchase their tickets back at a higher price (or in exchange for a voucher for a future comparable trip) and then resell those tickets at a much higher price on the current market. Those willing to travel at the current market price would thus be able to bid for a seat, and those traveling for discretionary purposes being compensated for opting out. Airlines would thus be able to recover some of the substantial losses in revenue they incur during such disruptions by maximizing their revenue on existing flights. For humanitarian reasons, such as reuniting families or accommodating persons with medical conditions, seats can also be made available by swapping arrangements between high-priority passengers and those being more flexible. A swapping market can also spontaneously emerge through online social networks.
d. Modal shift
Ideally, passengers or freight mobility should shift towards modes that have a higher capacity and resiliency. However, if a public transit system is shut down because of a disaster, it can take several days to be brought back online. Meanwhile, those seeking to commute may be forced to use their automobiles (and carpool), where they would be using public transit under normal circumstances. This exacerbates congestion and may even lead to fuel shortages. For air transport, since most movements remain regional in scale (city pairs of less than 1,000 km), it can be expected that passengers will switch to alternative modes, which can be ill-prepared to deal with the sudden demand surge. The market for alternative modes mostly concerns the automobile, rail, buses, and even ferries where the situation warrants. Those alternative modes must react quickly by adding as much capacity as possible, which may occur more effectively if those contingencies are planned in advance.
A convergence of passengers towards terminals (rail and bus stations) can create undue crowding and queuing, which could be mitigated by using satellite travel arrangement facilities where passengers could be offered a range of multimodal options that could be booked. Then, a passenger would only need to show up at the terminal before boarding time. There is also a substantial opportunity to remove discretionary travel on alternative modes by creating swapping markets for passengers willing to trade their tickets in exchange for a monetary sum or a voucher valid for future travel. There is, therefore, an opportunity for the alternative mode to gain market share once the crisis is over.
For freight, modal shifts over long distances are possible strategies, particularly if it concerns more resilient modes such as rail or maritime transport. For short distances, such as deliveries or terminal hauling, modal shift is less likely since there are limited alternatives. Therefore, deliveries need to be postponed, consolidated, and prioritized. The outcome can be a lack of several consumption goods in local markets.
Acute geographical differences have emerged in mitigating and recovering from disasters, particularly between developed and developing economies. Because of differences in infrastructure quality, more stringent building standards, and effective governance, a similar disaster taking place in a developing economy is likely to have more impacts than a developed economy. These differences may even be reflected at the urban level, where depending on their spatial structure, cities may be impacted differently by a similar disaster.
- Transport Safety and Security
- Climate Change and the Adaptation of Transport Infrastructure
- The Nature of Transport Policy
- Transport Planning and Governance
- Transportation and Pandemics
- Chang, S.E (2003) “Transportation Planning for Disasters: An Accessibility Approach”, Environment and Planning A, Vol. 35, pp. 1051 – 1072.
- Kappenman, J. (2012) “A Perfect Storm of Planetary Proportions”, IEEE Spectrum, February.
- Linkov, I. and J.M. Palma-Oliviera (eds) (2017) Risk and Resilience, Amsterdam: Springer.
- Luke, T.C. and J-P Rodrigue (2008) “Protecting Public Health and Global Freight Transportation Systems during an Influenza Pandemic”, American Journal of Disaster Medicine, Vol. 3, No. 2, pp. 99-107.
- National Academies of Sciences, Engineering, and Medicine (2014) A Guide to Regional Transportation Planning for Disasters, Emergencies, and Significant Events. Washington, DC: The National Academies Press.
- OECD (2011) Future Global Shock – Improving Risk Governance, Paris: OECD Publishing.
- Osterholm, M.T. (2005) “Preparing for the Next Pandemic”, Foreign Affairs, July/August, pp. 24-37.
- Özdamar, L, E. Ekinci and B. Küçükyazici (2004) “Emergency Logistics Planning in Natural Disasters”, Annals of Operations Research, Vol. 129, pp. 217 – 245.
- Scott, D., D.C. Novak, L. Aultman-Hall, and F. Guo (2006) “Network robustness index: A new method for identifying critical links and evaluating the performance of transportation networks”, Journal of Transport Geography, Vol. 14, pp. 215- 227.
- Weiland, S., A. Strong and B.M. Miller (2019) Incorporating Resilience into Transportation Planning and Assessment. Santa Monica, CA: RAND Corporation.