NIST National Construction Safety Team 

Investigation of Hurricane Maria

NCST Advisory Committee Meeting – June 14, 2023

Cross-Project Panel Theme 1: Hospitals 

DongHun Yeo, Joseph Main, Judith Mitrani-Reiser
• Hospitals play a critical role in emergency response and recovery

• Hospitals in Puerto Rico are designed using the same building codes 

and standards as in the mainland U.S.

• Hurricane Maria’s impacts on hospitals included:

− Damage to hospital buildings, including extensive nonstructural damage

− Loss of supporting infrastructure, including power, water, transportation

• Damages to hospital buildings and supporting infrastructure affected:

− Functionality of hospitals

− Access to hospitals

• Hospital accessibility and functionality played a significant role in 

deaths associated with Hurricane Maria

Hospitals Theme: Motivation

2
Hazard Characterization

Critical Buildings Morbidity & Mortality

Recovery of Social 

Functions

Hospitals Theme: Integration of Data Streams

• Wind loads on buildings and 

rooftop equipment

• Damage to building 

components and contents

• Impacts on hospital functions

• Damage to hospitals

• Disruption of services

• Recovery of services 

over time

• Wind exposure, including 

topographic speedup

• Other hazards: rainfall, 

flooding, landslides

• Causes of death

• Search for health care

• Damage to hospitals

• Disruption of hospital functions

3
Hazard Characterization

Critical Buildings Morbidity & Mortality

Recovery of Social 

Functions

Hospitals Theme: Integration of Analysis

What were the damages to 

buildings and impacts on 

supporting infrastructure? 

How did these affect 

hospital functions?

What role did disruptions in 

hospital functions and access 

play in deaths?

What were the 

hazard conditions 

at hospital sites?

How did hospital 

services recover over 

time following the 

hurricane? 

4
Hospitals Theme: Highlighted Projects

Hazard Characterization

Performance of Critical Buildings

Morbidity & Mortality

70 80 90 100 110 120 130 140 144

Peak gust wind speed without topographic effects (mph)

1 mph = 0.447 m/s

5
Hazard Characterization

Performance of Critical Buildings

Morbidity & Mortality

Hospitals Theme: Highlighted Projects

70 80 90 100 110 120 130 140 144

Peak gust wind speed without topographic effects (mph)

1 mph = 0.447 m/s

6
0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6

Topographic Speedup Factor

70

80

90

100

110

120

130

140

San Juan Region

Utuado Region

Caguas Region

Humacao Region

Other

Wind Speed, including Topographic Effects (mph)

Hazard Exposure During Hurricane Maria

0

5

15

40

100

250

500 [mm]

Topographic Speedup Factor (TSF) at hospital sites

Flood depth 

modeling

(Bristol U)

• Data collected on rainfall, inland flooding, landslides, and coastal inundation

• Hurricane Maria wind field model developed for Puerto Rico, including topographic effects

Wind field model:

peak gust speed with 

topographic effects

Total precipitation 

(NCEP Stage IV)

Landslide density

(USGS) 

PRELIMINARY ANALYSIS

Flood depths computed using the method in: Archer et al. (2022) “Current and Future 

Flood Risk From Tropical Cyclones in Puerto Rico Under 1.5°C and 2°C Climate Change,” 

EGU General Assembly 2022. <https://doi.org/10.5194/egusphere-egu22-2871> 

Hospital Bella Vista

Univ. Pediatric Hospital

7
Analysis of Rainfall Data

• Analyzed hindcast data from an ensemble of 14 high-resolution 

Weather Research and Forecasting (WRF) models and 

compared results to USGS rain gauges and NCEP Stage IV data

− Ensemble mean tracks well with USGS gauge data

− NCEP Stage IV rainfall exceeds USGS gauge data and WRF models

• Developed uncertainty model to understand the relationship 

between USGS gauge measurements and NCEP Stage IV data

− Time-varying model indicates that the two datasets are well 

correlated initially but then deviate for some stations (likely 

associated with rain gauge failure)

NCEP Stage IV

USGS

Precipitation time-history at a station: 

USGS rain gauge vs. NCEP Stage IV

Comparison of WRF 

ensemble results with 

island-wide averages of 

USGS rain gauge 

measurements and 

NCEP Stage IV data

PRELIMINARY ANALYSIS

Hurricane Maria WRF hindcast simulations

Performed by Prof. Aponte (UPRM) under NSF Award No. 1841979

8
Field Measurements and CFD Modeling

• Completed 2nd year of continuous 3-s wind speed/direction measurements on 3 cell towers in Yabucoa region

• Repaired anemometers damaged by Hurricane Fiona and measured as-installed orientation angles of 

anemometers on YTA and YMN towers

• Performed CFD simulations using previously developed canopy model with satellite-based data on forest cover

• Compared flow field data from field measurements, wind tunnel tests, and CFD simulations

Anemometers as installed 

on YTA tower

Boom

Anemometer

Comparison of field measurements, 

wind tunnel data, and CFD at YTA tower

CFD simulations of flow over topography 

and forest cover in Yabucoa region

PRELIMINARY ANALYSIS

|U| [m/s]

0

20

YTA 

Tower

YMN 

Tower

Along-wind velocity magnitude at zg = 10m

Topographic Speedup Factor

9
Wind Tunnel Testing and CFD Modeling

• Completed processing and curation of wind tunnel test data from topographic models

• Shared curated velocity probe data from PR topographic models with ARA to inform final wind field model

• Compared topographic speedup factor (TSF) from wind tunnel tests and Computational Fluid Dynamics (CFD)

CFD: mean along-wind velocity (U) magnitude

Wind Tunnel: Velocity probe measurement locations

Hospital Bella Vista

Hospital Bella Vista

Wind angle: 210°

Wind angle: 210°

Topographic speedup at Hospital Bella Vista site

PRELIMINARY ANALYSIS

Wind

Wind angle: 210° Wind angle: 210°

Mean Velocity Topographic Speedup Factor

10
Hazard Characterization

Performance of Critical Buildings

Morbidity & Mortality

Hospitals Theme: Highlighted Projects

70 80 90 100 110 120 130 140 144

Peak gust wind speed without topographic effects (mph)

1 mph = 0.447 m/s

11
Hospital Damage Observations

• Common themes at 5 selected hospitals: (preliminary observations from Phase 1 evaluations)

− Roof cover damage

− Rooftop equipment damage

− Broken/damaged windows and doors

− Significant water intrusion into buildings

− Damage to interior finishes and contents

• Phase 2 site visits and interviews recently completed for all 5 of the selected hospitals:

− Further details on damage to building components, systems, and contents

− Information on impacts to hospital functions and operations

Phase 1: Initial document 

collection and review

Phase 2: Interviews, site visits, 

additional document review

12
Wind Tunnel Test Data for Hospitals

Completed Data Curation and Processing for 

Both Hospital Facilities:

• Measured pressure data normalized as 

nondimensional pressure coefficients

• Summary statistics calculated for measured 

data, including peaks estimated by fitting an 

extreme value distribution to the data

• Visualizations developed for measured 

pressures at tap locations

13 Boundary Layer Wind Tunnel at University of Florida PRELIMINARY ANALYSIS
Wind Tunnel Test Data for Hospitals

Completed Data Curation and Processing for 

Both Hospital Facilities:

• Incorporated tubing response functions to 

correct for effects of tubing dimensions, 

temperature, and atmospheric pressure

• Applied filtering in frequency domain to 

eliminate harmonics in measured pressures 

caused by Flow Field Modulator (FFM)

Tubing response function Pressure harmonic

FFM fan elements in Boundary Layer 

Wind Tunnel at University of Florida 

14 PRELIMINARY ANALYSIS
Hazard Characterization

Performance of Critical Buildings

Morbidity & Mortality

Hospitals Theme: Highlighted Projects

70 80 90 100 110 120 130 140 144

Peak gust wind speed without topographic effects (mph)

1 mph = 0.447 m/s

15
Verbal Autopsy & Socio-Environmental Survey

Non-communicable diseases

Communicable, 

maternal, neonatal, & 

nutritional diseases

Undetermined

Injuries

• A total of 410 interviews were conducted 

with next-of-kin informants.

• Of these, 11% of the deaths occurred the 

day of the hurricane’s landfall, and 88% 

occurred in the 14 days after landfall.

• Objective is to ascertain the cause and 

conditions surrounding deaths that took place 

within 14 days after landfall.

• The population of the VA+S’E consists of all 

deaths (n = 1804) occurring between Sept 20 

and Oct 4, 2017.

Place the ambulance (911) or alternative 

service took deceased to search for care

%

Emergency Room 22

Hospitalization services/hospitals 72

Primary health care centers/health center 2

Urgent care services 2

Other 2

PRELIMINARY ANALYSIS 16
Verbal Autopsy & Socio-Environmental Survey

Preliminary assessment of the VA=S’E data shows: ~66% of individuals sought health care in at least one 

place; ~47% of individuals with low socio-economic status didn’t seek any care; and the more frequently 

mentioned hospital disruptions were power outages, loss of AC/ventilation, and shortage of staff.

# places visited in search of care

Frequency

0 2 4 6 8

0 50 100 150 200

Disruptions next-of-kin informants noticed 

where deceased was hospitalized

%

Power outage 96

A/C (ventilation) not functioning 71

A flood from rising water entered building 21

Rainwater entered building during the storm 30

Water leaked through the ceiling 23

Interruption of water service 19

Not enough staff 57

Not enough medical equipment 41

Medical gases (oxygen) were not available 15 PRELIMINARY ANALYSIS 17
Preliminary Observations from Hospital Function Surveys Supporting Mortality Assessment:

• Power generators of two hospitals had limited capacity and could not supply sufficient power.

• Of the 6 hospitals surveyed, all but one facility reported significant building damage (e.g., window/door 

and roof damage), resulting in rainwater ingress and flooding in most buildings.

• Damage forced patients, some critical, to be moved to hallways and other floors; moving patients was 

difficult due to loss of elevator functions (resulting from loss of power and flooding of machine rooms).

• Hospital personnel reported the following as significant challenges: inventory problems with fuel 

(diesel), medicine, water, and oxygen, as well as staff burnout (particularly 2nd week after landfall).

Hospital Function Surveys

Source: FEMA Source: FEMA Source: FEMA Source: FEMA 18
Questions?

Theme 1: Hospitals Theme 3: Infrastructure 

Dependencies

Theme 2: Sheltering

DongHun Yeo, Joseph Main, 

Judith Mitrani-Reiser

Marc Levitan, Katherine Johnson, 

Maria Dillard

Ken Harrison, Jennifer Helgeson, 

Maria Dillard