Resilience of Ports Against Natural Hazards

By Deepak Pant, Ph.D., P.Eng., Greg Brunelle, MS, MA, Youngsuk Kim, Ph.D., Jaskanwal P. S. Chhabra, Ph.D., & Shabaz Patel, MS

Introduction

The resilience of infrastructure can be defined as “the ability to suffer less damage and recover more quickly from adverse events” (Fisher et al. 2017). In order to evaluate the resilience of ports against natural hazards, their damage and recovery must be properly modeled. For this, it is important to understand the physical vulnerabilities of their components, typical recovery durations, and the factors controlling recovery. It is also crucial to understand that different perils impact ports in different ways and controlling factors governing recovery could be different for different perils.

This article provides an overview of key components of ports and their operations, a summary of the review of historical damage and recovery of ports from natural hazards, and the identification of key factors that control their recoveries in order to understand port resilience more deeply.

Overview of Major Components of Ports and Their Operations

Review of Historical Damage and Recovery

Earthquakes

Ports have suffered various degrees of damages in past earthquakes. While all the components of ports discussed in the previous section are vulnerable to earthquakes, wharves and cranes are the most vulnerable components in terms of port functionality. There are three main causes of damage to ports during earthquakes: (1) liquefaction, (2) ground deformation not affiliated with liquefaction, and (3) ground shaking (Pachakis and Kiremidjian 2004). While cranes are generally considered safe against seismic forces (Kosbab 2010), they can be damaged by shaking as well as due to damage of wharves, which are the most vulnerable components of a port.

Despite this vulnerability, we found in our research that U.S. ports performed well in past earthquakes because of their inherent redundancy and because they have not yet been subjected to damaging ground motions.The 1989 Loma Prieta earthquake affected the port of Oakland in that one container terminal suffered moderate damage. Nonetheless, the cargo from the damaged terminal was diverted to other terminals at the port, resulting in zero downtime (Pachakis and Kiremidjian 2004). The 1994 Northridge earthquake impacted the port of Los Angeles similarly; one container terminal suffered some minor damage, and overall no reports of downtime at the port could be found.

On the other hand, ports in Japan have experienced several damaging earthquakes. The 1995 Kobe earthquake impacted the Port of Kobe and caused widespread liquefaction and subsidence of wharves and caused moderate to severe damage to several cranes. While the repairs of damaged components were carried out for over two years, the full functional recovery was estimated to be achieved in less than two years. The 2011 Tohoku earthquake also caused widespread damage to ports. A combination of tsunami and ground shaking was the leading cause of the damage (Sugano et al. 2014). Wharves at the Port of Onahama were impacted by ground shaking and liquefaction which led to horizontal displacement of caissons, subsidence of backfill and some minor damage to cranes. The port of Onahama was able to resume full functionality in 6 months as measured by the volume of cargo handled by the port. During more recent events, such as the 2016 Kumamoto earthquake and the 2018 Hokkaido Eastern Iburi earthquake, the ports in Japan have performed well with some minor liquefaction and settlement of wharves, and the downtimes have been in the order of several days for the Kumamoto Port and the Tomakomai Port.

Port of Haiti, on the other hand, was devastated by the 2011 Haiti earthquake and both of the port’s wharves were completely destroyed and cranes were submerged in water and the recovery process was expected to take years (DesRoches et al. 2011).

In summary, earthquakes can cause significant damage to ports, and the recovery can take between several days to years depending on the degree of damage.

Windstorms

The main type of damage that windstorms can cause to ports are: (1) roof and wall damage of structures, particularly warehouses and (2) crane damage. Typically ports slow down their operations ahead of a large windstorm and are shut down during the duration of the storm. A comprehensive review of port slow-down and closure durations due to windstorms can be found in Verschuur et al. (2020). The focus herein is on the physical damage caused by windstorms and recovery durations following the storm. Damage to warehouses has occurred in almost all major hurricanes and typhoons around the world, but it typically does not cause functionality disruptions.

Cranes, on the other hand, are integral components of ports which are required for their functioning, and cranes have suffered damage in past windstorms. Although cranes are designed to resist wind loads, oftentimes there is a disconnect between crane design and crane-to-wharf connection design, which can cause failure of the crane-to-wharf connections referred to as tie-downs (McCarthy et al. 2007). Cranes are typically tied down to wharves ahead of strong windstorms to protect them from derailing and getting damaged.

In the US, there have been some instances of tie-down failures leading to crane damage. For example, the tie-down failure of one crane led to its severe damage at the port of New Orleans subjected to 2005 Hurricane Katrina (Cuffman et al. 2006).

One of the most devastating impacts of crane failures due to windstoms occurred at the Port of Busan in South Korea during the 2003 typhoon Maemi, which resulted in a sequential collapse of six cranes initiated by tie-down failures.

In Japan, some instances of crane collapses are reported, but they are mainly caused by not tying them down to the wharf ahead of the storm. For example, the 2018 Typhoon Jebi caused the collapse of 2 cranes at the Port of Amagasaki because the cranes were not tied down to the wharf ahead of the storm. Similarly, in 2006, one crane collapsed at the port of Niigata due to strong winds, and the recovery period for that crane was about 18 months.

Overall, the recovery data on cranes were less documented, but they are known to have long lead times. For example, the crane supplier Kalmar Global states that the lead times for purchasing a new crane are 12 to 24 months. In summary, windstorms can cause severe damage or collapse of cranes resulting in very long recovery times in the order of months to years.

Floods

In the US, the ports have suffered various degrees of damages due to floods. The port of New Orleans was subjected to flooding due to the 2005 Hurricane Katrina, and almost one third of the port was destroyed due to floods. This was rather an extreme event from a view point of its regional impact, and the recovery was expected to take more than 6 months.

The port of New York and New Jersey was severely impacted by flooding from the 2012 Hurricane Sandy. The damage included debris accumulation on the terminal and the damage of electric equipment etc. The port was fully functional in 7 days.

In Japan, the 2018 Typhoon Jebi caused widespread flooding at a number of ports including the ports of Sakai Senboku, Hanan, Osaka, and Kobe. The damage at these ports included debris accumulation, flooding of cargo handling vehicles, and the damage to electrical equipment. At all of these ports, the limited functionality was restored within a day while full recovery took 8 days.

In summary, floods can cause significant damage to ports, but their recovery is rather quick and generally takes less than a week, but it could take longer depending on the severity of the flooding.

Key Controlling Factors

Repair of damaged components

Based on the review of historical events, for earthquakes, liquefaction of wharves and damage of cranes was the most dominant factor controlling recovery. For floods on the other hand, flooding of wharves and flooding of electrical equipment were detrimental in controlling the recovery. For windstorms, crane damage and, in particular, crane-to-wharf tie-down failure was the controlling factor.

Redundancy

Repair Vs functional recovery

Scale of the disaster and interdependence on other infrastructure

Pre-event slow-down and duration of hazard

Conclusions

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