Abieyuwa Aghayere, PhD
On Tuesday, April 18, a parking garage at 57 Ann Street in Lower
Manhattan collapsed, killing one person, injuring five others and
causing the evacuation of several adjacent buildings. In the days
following the collapse, New York officials scrambled to inspect similar
structures, immediately shuttering four and marking many others in need
of repair.
Though the exact circumstances that caused the garage collapse remain
undetermined, it serves as a stark reminder that consistent evaluation
and maintenance of aging structures is critical.
Abieyuwa Aghayere, PhD
, professor of civil, architectural and environmental engineering,
shared his thoughts on what may have contributed to the collapse and, in
observance of May as Building Safety Month, what practices local
governments should adopt to address aging infrastructure to avoid
similar disasters.
What do we know about what caused the parking garage collapse?
The root cause of the collapse has not been determined at this time –
the forensic investigation is currently underway by the New York City
Department of Buildings (NYC DOB) and would involve reviewing the
collapse debris, the load on the structure at the time of collapse, and
the structural drawings for the garage if they are still available, and
any other documents related to the building such as the engineering
repair plans for the building prepared by a licensed structural engineer
in 2010.
What we do know is that the building was built in 1925 and converted to
a parking garage in 1957, which means the building was almost 100 years
old at the time of collapse. Given the advanced age of the building and
the exposure of the structure to the elements — snow, road salt, rain,
etc. — some material deterioration would have taken place over time,
depending on the level of maintenance that was carried out in the
structure over the years. The NYC DOB, according to the New York Post,
has stated that “..the collapsed parking garage had open violations
relating back to 2003-2004” and a summons for crack violations was
issued to the building owners in 2009. In response to the violation, a
set of garage repair plans for the building was filed in 2010 with the
NYC DOB by a licensed structural engineer, but it is not known if the
repairs recommended by the engineer were carried out, and if what caused
the cracks and deterioration were investigated or if any non-destructive
evaluation was carried out on the structure. According to the NYC DOB,
no “Certificate of Correction” was filed with the city by the owners of
the building.
There is no question that the maintenance and repair of buildings is the
responsibility of the building owner, but whose responsibility is it in
New York City (or any other jurisdiction) to enforce the rules, and
ensure that building owners follow up on repairs and maintenance — the
NYC DOB, the building owner’s insurance company, the building owners
themselves, or a combination of these entities? I believe that the city
or jurisdiction having authority has the enforcement and follow-up
responsibility, but it is in the financial interest of the insurance
companies to also pitch in and ensure that their insured properties are
being maintained and repaired adequately.
Officials did a speedy investigation of other parking structures and
shut down four additional garages. What might they have seen in those
structures that caused concern?
The NYC Department of Building (DOB) inspectors according to the New
York Post “identified roughly 4000 garages currently being used across
the five boroughs” and “at least 61 of the locations currently have open
Class 1 violations against them for failing to maintain the buildings..”
Class 1 violations - according to the NYC DOB - are structures that are
“immediately hazardous” and “warrant immediate corrective action.” The
violations they found were “related to structural stability or
structural issues.” The NYC DOB mandated the owners of the parking
garages to engage licensed structural engineers to conduct more in-depth
and rigorous condition assessment of the buildings and develop
recommended repair strategies.
What changes to inspection practices should happen to prevent things
from getting this bad?
Following the collapse of a two-level parking garage in Johnson City, NY
in 2015, New York State instituted a new rule, starting in 2019, that
mandated periodic inspections of parking garages every three years by a
licensed engineer. However, New York City has its own building code
requirements which mandate periodic condition assessment of parking
garages by a licensed engineer every six years. NYC has staggered the
inspections of parking garages within their five boroughs to take place
in two-year intervals (2022-2023, 2024-2025, 2026-2027), and the parking
garage that collapsed was scheduled to be inspected in the first round
of inspections.
I believe that the 6-year intervals for inspections or parking garages
may be too long for older garages that have been subject to material
degradation for many years from exposure to the elements, and for which
there may have not been frequent or periodic maintenance. Parking
garages are basically “stacked vehicular bridges” and given that bridges
are inspected every 24 months, it would make more sense to inspect
parking garages no later than every 2 or 3 years – as the New York State
rule for parking garages requires.
What kinds of technology might be able to help keep an eye on at-risk
structures?
There are several non-destructive evaluation (NDE) methods that could be
used during physical inspections and condition assessments of these
structures. They include Ground Penetrating Radar (GPR), impact echo,
infrared thermography, ultrasonic pulse velocity, and half-cell
potential, to name a few. Sensors could be used, but they would need to
be installed at targeted locations.
Since parking structures are massive in size and since the cracks and
material degradation and defects can occur at many locations, it may be
prohibitively expensive at this time to place multiple sensors all
around the structure to monitor the structural health. Then, there is
the question of who will be responsible for reviewing, analyzing and
following up on the massive amount of data that will be generated from
the multitude of sensors. I believe that periodic physical inspection or
condition assessment of parking garage structures by a licensed
structural engineer – aided by technology – and frequent maintenance of
the garages by the building owners are currently the more efficient
approach to ensure the health of these aging structures.