What are the consequences when these vulnerabilities are not understood?
Regrettably, when the risks posed by natural hazards are not properly addressed,
hospitals may themselves become victims of the disaster. The impact of past
natural disasters on hospitals provides a valuable lesson for future preparation.
Tropical Storm Allison
The effects of Tropical Storm Allison on patient care at Houston-area hospitals
in June 2001 provided several informative examples of what can go wrong when
flood vulnerabilities are not clearly understood. In this case, flooding of
the hospitals occurred not from nearby bayous overflowing their banks as was
typically expected, but from sheet flow due to intense, short-term rainfall.
Figure 1 shows a rainfall map for Harris County, Texas, as a result of Tropical
Storm Allison. As rainwater runoff began to overwhelm existing storm drainage
systems, the resulting floodwaters flowed overland, inundating basement, ground,
and first-floor levels of hospitals throughout the area. The entire electrical
room, shown in Figure 2, was inundated with water. Particularly hard hit was
the Texas Medical Center. A key vulnerability in almost every case was the location
of electrical switchgear and automatic transfer switches.
Electrical switchgear in a building serves as a junction box between the
transformer vault, which receives power from the local utility, and large electrical
conduits that branch out into a hospital, directing power to numerous sources.
If inundated, the switchgear will malfunction, resulting in a complete blackout
of the hospital. Repair and replacement of this equipment can cost millions
of dollars and take weeks to complete.
To be sure, hospitals have emergency generators to provide back-up power
in the event of a loss of main power from the local utility. Transfer from main
power to the emergency generators occurs automatically through a transfer switch.
However, automatic transfer switches are susceptible to the same type of flood
damage as switchgear. Ironically, the emergency generators of many of the hospitals
functioned properly, yet were of no value since the automatic transfer switches
With both types of equipment, the question is "what type of flooding event
(e.g., 500-yr storm surge) might be expected to occur, and if such an event
happened, are the switchgear and automatic transfer switches protected"? In
the case of Tropical Storm Allison, flooding due to sheet flow was not fully
accounted for by many of the affected institutions. Moreover, most of the equipment
was located below grade in basements that were not adequately protected from
In the case of extreme winds, the hurricanes of 2004 that struck Florida
provide useful insights into what can go wrong even when the type of event has
been taken into account. Hurricane Charley, a weak Category 4 storm, made landfall
in Charlotte County along the western coast of Florida. A regional medical center
located in the area sustained significant damage to its roof and windows, resulting
in rainwater infiltration into patient rooms and other medical service areas.
As the storm passed through the area, the hospital lost main power, resulting
in the activation of its emergency power generators. However, the generators
only had enough diesel fuel to keep the facility operating for 28 hours. A back-up
emergency generator and fuel tank, shown in Figure 3, had to be brought in to
provide power after the existing generator ran out of fuel. The local water
utility also was unable to provide fresh water to the hospital. Hence, patients
were evacuated to nearby hospitals on Sunday after the storm hit the site.
Main power was restored to the hospital four days after Hurricane Charlie
struck, followed by water service a day later. A month passed before the hospital
became fully operational. Given its exposure in a hurricane prone region, the
hospital had anticipated, and ostensibly was prepared for, a power outage. However,
even though priority is given to restoration of power to medical facilities
like a hospital in the immediate aftermath of a hurricane, past experiences
have revealed that it can take several days before power is back on following
a major hurricane. Hence, it is advisable to have at least a 72-hour supply
of fuel available to power the generators.
A four-story patient building of another hospital in Charlotte County sustained
major damage to its roof covering and windows, along with an adjoining two-story
building housing the operating room, intensive care unit, and the cardiac catherization
lab. The resulting rainwater intrusion forced evacuation of patients from these
areas. However, nearby a newer, one-story building that housed the emergency
room sustained no damage. A major reason was the use of impact-resistant window
glazing systems, as shown in Figure 4. In this case, compelled in part by the
enforcement of stricter building codes, the designers of the new emergency room
were able to mitigate the detrimental effects of wind-borne debris that often
cause much of the damage to a building.
A community hospital located in De Soto County, north of Charlotte County,
also sustained widespread damage to its windows and roof coverings. The subsequent
intrusion of rainwater and broken glass into the patient rooms resulted in the
relocation of patients to interior areas on the first floor. However, though
main power was lost as the storm passed through the area, the emergency power
generators were able to provide backup electricity to the facility until main
power was restored 36 hours later. Moreover, although the local water utility
was unable to provide fresh water to the facility, the hospital had a well on-site
that they could rely on as a back-up source for fresh water. Hence, the facility
was able to remain operational during, and in the aftermath of, the storm.
Hurricane Frances, a weak Category 2 storm, made landfall roughly midway
along the Atlantic coastline of Florida, resulting in limited overall damage
to a regional medical center located in the area. However, two elevator penthouses
on top of the main six-story patient building of the hospital sustained major
damage, resulting in a complete loss of the elevator equipment inside, thus
rendering all four elevators in a patient tower, serving floors two through
six, inoperable. Subsequently, a majority of licensed beds in the obstetrics,
pediatrics, and intensive care units were not accessible. Apparently not as
much consideration was given to the design of the penthouses in terms of their
vulnerabilities to hurricane-force winds and the associated wind-driven rain
that accompanies them. Repair of the hospital penthouses following the Hurricane
is shown in Figure 5.
The 1971 San Fernando earthquake in California focused considerable attention
on seismic safety for hospitals within the State of California. The Veterans
Administration hospital in San Fernando and the Olive View hospital in Sylmar
experienced significant structural damage with loss of life as a result of the
In 1994 the State of California adopted State Senate Bill 1953 (which amended
the 1983 Alquist Act) that provided additional requirements to ensure that both
structural and nonstructural components in hospitals perform adequately in the
event of strong ground motion.
However, there are many areas of the United States that can be classified
as being in either a moderate or high region of seismicity that do not have
the same stringent requirements as California for the design of hospitals or
acute care facilities. Although the new International Building Code will help
to enhance the design requirements for new hospitals in the regions outside
of California, existing hospitals or acute care facilities will typically not
receive the same scrutiny. Considerable attention should be paid to emergency
power generation systems and other utilities, in both new and existing hospitals,
to ensure that the equipment performs adequately in the event of strong ground
There are important lessons to be learned from past natural disasters. Hospital
administrators must first have a clear and complete understanding of the types
of natural disasters that can affect their facilities, specifically the magnitude
and probability of occurrence. Given these exposures, they must identify vulnerable
areas of the hospital complex, particularly those areas that provide essential
support to the facility: namely electrical rooms, air handling equipment, fire
protection systems, medical gases, and communications. Finally, once exposures
and vulnerabilities are identified, they must establish a cost-effective mitigation
plan to minimize the risks. Several methods are available to determine the optimal
amount of funding to invest in order to reduce the risks posed by natural hazards.
Such an investment in mitigation will ensure that a hospital is able to fulfill
its essential role as a provider of critical care to victims following a natural
R. Bailey is a technical manager with
the Extreme Loads and Structural Risk Division of ABS Consulting in Houston.
He has more than 20 years of experience in areas related to wind engineering,
construction materials, structural analysis, and design. His primary responsibility
has been determining risk exposure of residential, commercial, and industrial
properties to hazards associated with extreme wind and flooding events for insurance
companies, private industrial operations, and government agencies worldwide.
Dr. Bailey has made presentations nationwide at conferences and to trade organizations.
He also has appeared on several television documentaries regarding hurricanes
and tornadoes. He earned his BS, MS, and Ph.D. in Civil Engineering from Texas
Tech University, and is licensed to practice as a Professional Engineer in Texas.