Well-Known Investigations

Below is just a sampling of our well-known investigations. To browse through our past projects, please visit our Services page and select a practice and/or industry. 

Turkish Airlines Crash, Paris France
March 3, 1974
turkishTurkish Airlines Flight 981 had just finished loading its cargo bay at Orly Airport in Paris. A baggage handler was having trouble shutting the cargo door but managed eventually to “close” it. Twelve minutes later the DC10 aircraft crashed in a forest 21 miles away. It was determined that the door latching mechanism was deficient because the handle could be forced “closed” even though the door locking mechanism was not properly engaged.
Amoco Cadiz Grounding and Spill, Brittany Coast, France
March 16, 1978
cadizSupertanker Amoco Cadiz ran aground off the coast of France causing one of history’s largest oil spills. The grounding occurred due to the hydraulic/mechanical failure of the steering system. Exponent determined the cause of the system rupture.
Kemper Arena Roof Collapse, Kansas City, MO
June 4, 1979


kemperThe Kemper Arena in Kansas City had just been host to the Republican National Convention. In the course of a violent rainstorm, the roof of the massive building collapsed.  Exponent inspected the debris and zeroed in on the steel truss connections in the flat portion of the roof between the famed Space Frames, which held up the roof.


Alexander Kielland Rig Accident, North Sea
March 27, 1980
kiellandOn the evening of March 27, 1980, some workers on the Alexander L. Kielland floating hotel platform in the North Sea were gathered to watch a movie. Suddenly they heard a loud cracking noise. The platform immediately tilted to a 20-degree angle. As openings filled with water, the platform continued to tilt and capsized. In all 123 crewman died. Exponent’s investigation involved stress analysis, fracture mechanics, and hydrodynamic stability analysis of the platform.
Hyatt Regency Walkway Collapse, Kansas City, MO
July 17, 1981
hyattOn July 17, 1981, the Hyatt Regency Hotel in Kansas City was hosting a Friday evening dance party. Above the lobby, two walkways supported dozens of party-goers overlooking the festivities. Suddenly the walkways collapsed, killing 114 people.  Exponent engineers sifted through the wreckage for four days and concluded that the collapse occurred when a welded beam which supported one of the walkways failed. 
World Airways Crash, Boston, MA
January 23, 1982
World Airways Flight 30H was on approach for landing at Boston’s Logan Airport. The DC-10 broke out of the low cloud ceiling to the right of the runway, and banked to line up for touchdown.  The aircraft touched down long and could not stop before bounding over a sea wall and into Boston Harbor.  Exponent analyzed information from the flight data recorder and produced a computerized animation overlaid with the actual cockpit voice recording.  The animation depicted a “pilot’s eye” view of the approach, touchdown, and rollout of the plane, dramatically illustrating the icy plunge into the sea.
Glomar Java Sea Drillship Capsize, South China Sea
October 25, 1983
The drill ship Glomar Java Sea was caught in a typhoon in the South China Sea east of Vietnam. The 400-foot oil exploration ship was unable to survive the storm and sunk. Eighty-one people were aboard. Exponent was called in to analyze the causes.
GM X-Car Investigation

In 1985 General Motors “X-car” was declared to be unsafe by the National Highway Traffic Safety Administration.  Exponent undertook one of the largest automotive accident studies at that time to analyze brake design defect and assist General Motors disprove the allegations.

Dupont Plaza Hotel Fire, San Juan, Puerto Rico
December 31, 1986
dupontLabor unrest had not dampened the 1986 New Year’s Eve celebration as guests gathered in the casino and ballrooms of the DuPont Plaza Hotel in San Juan, Puerto Rico.  Three explosions were heard and the casino was engulfed in a wall of flames.  Nearly 100 people were killed.  Exponent engineers confirmed that arson was the cause of the fire.  Damage and death was caused by rapidly spreading flames, not by smoldering materials.
Northwest Airlines Crash, Detroit, MI
August 16, 1987

A Northwest Airlines jetliner carrying 155 people crashed during takeoff from the Detroit Metropolitan Airport after climbing less than 50 feet off the ground.  The McDonnell Douglas MD-80 was scheduled to fly non-stop from Detroit to Phoenix and continue to Santa Ana, California, but the aircraft had difficulty gaining altitude and the left wing was severed after striking a light pole approximately 2, 700 feet beyond the end of the runway.  The jet subsequently careened out of control, crashed into a railway overpass, and disintegrated along an adjacent road.  Two people on the ground and 154 people on-board the plane were killed by the crash; the only passenger to survive was a four-year-old girl.  Exponent engineers performed a complete accident reconstruction using aerodynamic models and a computer simulation to show that the flaps required during normal takeoff were never deployed.
Suzuki Samurai Recall Investigation
samuraiThe Suzuki Samurai was alleged to be unsafe after Consumers Union released a 1988 video to the national press showing the Samurai tipping up onto its outriggers when negotiating a test course at 38 mph.  The federal government was soon petitioned to order a recall of the vehicle.  Exponent examined Consumers Union test procedures and demonstrated that the driver’s actions greatly influenced the test, and that the Samurai could readily negotiate the course.  Ultimately, the petition to investigate the Samurai was rejected by the federal government
PEPCON Explosion, Henderson NV
May 4, 1988 
pepconA massive fire and a series of explosions, the largest exceeding the equivalent of 1.5 million pounds of TNT, destroyed a ammonium perchlorate chemical plant in Henderson, Nevada, killed two people and caused more than $70 million in damages to the surrounding community.  Exponent concluded that a leak in a natural gas pipeline which passed underneath the plant contributed to the explosion. 


Piper Alpha Oil Rig Accident, North Sea
July 6, 1988 
Occidental Petroleum’s Piper Alpha was a billion dollar oil platform located in the North Sea off the coast of Scotland. An explosion on the platform resulted in a fire that completely destroyed the structure and cost 167 lives and millions of dollars a day in lost revenue. Exponent participated in the public inquiry conducted by the British Government under Lord Cullen.
Phillips Petroleum Plant Explosion, Pasadena, TX
October 23, 1989
phillipsThe Philips Petroleum polyethylene plant near Houston exploded when one of the reactors leaked a large amount of combustible material. The material was released from an open processing valve at the bottom of a reactor leg. It quickly formed a cloud which spread out over a large portion of the complex and ignited with sufficient force to register 3.5 on a seismic scale located at Rice University in Houston. The October 24, 1989 explosion and subsequent fire killed twenty-three people and resulted in an estimated 1.5 to 2 billion-dollar loss of the plant. Exponent performed the accident investigation.
Dunsmuir Train Derailment
July 14, 1991
 A 131-ton tank car derailed near the town of Dunsmuir, California, and landed upside down in the Sacramento River.  The tank car ruptured and spilled almost 20,000 gallons of pesticide into the water.  The deadly chemical destroyed fish and vegetation as it flowed 27 miles downstream and discharged into Lake Shasta.  Engineers from Exponent were called to inspect the tank car and provide modeling expertise for derailment accidents.
Oakland Hills Fire, Oakland, CA
October 20, 1991 
Fueled by drought, low humidity and high winds, a two-day fire storm swept death and destruction through the Oakland hills above the San Francisco Bay.  The October 20-21, 1991 fire killed at least 24 people, injured 148, and caused damages in excess of $2 billion.  The flames devoured 3,000 houses and apartments.  Engineers at Exponent worked with homeowners and contractors to identify and restore usable portions of building foundations in an effort to speed up reconstruction and reduce repair costs. 
James Dean Accident Investigation, Paso Robles, CA
deanOn September 30, 1955, James Dean, a popular actor, was killed in a two-car accident near Paso Robles, California. The police reported that Dean was speeding at 70 mph at the time of the accident. Thirty-five years later, Exponent was asked to reconstruct the crash for the NBC television series “What Happened?” Exponent found that Dean’s vehicle was traveling 55-60 mph at the time of the accident and was killed when an oncoming driver turned left in front of him.
Chicago Flood, Chicago, IL
April 13, 1992
chicago flood 3On April 13, 1992, adjacent construction  tore a 20-foot-long hole through the wall of a tunnel 20 feet beneath the bed of the Chicago River, some 50 feet beneath downtown Chicago. Over 200 million gallons of water surged through an extensive series of underground tunnels, affecting more than 30 major buildings, including City Hall and the financial markets. Lower levels of major office high-rises held up to 40 feet of water, and the city center was evacuated out of fear that electrical or utility connection failures could endanger lives. Exponent geotechnical, structural and materials engineers performed an investigation to help determine the cause of the accident. 
US v Lee Harvey Oswald
August 1992
jfkThe assassination of President John F. Kennedy on November 22, 1963 is one of the world’s greatest mysteries.  Two congressional investigations have concluded that Lee Harvey Oswald was the lone assassin, but many people have disputed these findings.   In 1992, Exponent engineers and scientists re-examined some of the evidence for the American Bar Association’s mock trial presentation: “The United States v. Lee Harvey Oswald.”  Our study of the gunshots and the paths of the bullets showed that an assassin on the sixth floor of the Texas School Book Depository could, alone, have completed the murder.  
NBC "Dateline" Investigation
November, 1992
dateline‚ÄčOn November 17, 1992, NBC “DATELINE” ran a story about the 1973-1987 GM C/K pickup trucks. The test shown on the program purportedly showed a collision between a passenger vehicle and the pickup at 30 mph which resulted in a fire. The NBC investigator noted that a “small hole was punctured in the fuel tank” which initiated the loss of fuel and the resulting fire. Exponent engineers investigated the test performed for NBC by The Institute for Safety Analysis (TISA). Exponent’s analysis found that TISA used rocket motors in the crash test to insure that the truck would ignite upon impact. Exponent also found that the integrity of the fuel tanks was not compromised. In February 1993, NBC “DATELINE” retracted their comments regarding the pickup and apologized to GM and the viewing public for the error.
Northridge Earthquake

During the aftermath of the January 1994 Northridge earthquake, a number of Exponent engineers volunteered as Safety Assessment Evaluators with California’s Office of Emergency Services. In addition to our work with the State of California, as well as the Federal Emergency Management Agency (FEMA), Exponent provided geotechnical and structural consulting to clients to evaluate the extent of earthquake damage to their properties. 

Murrah Federal Courthouse Bombing, Oklahoma City, OK
April 25, 1995 
okc bombingA 4,800-pound bomb, concealed in a rented truck, exploded 20 feet from the Alfred P. Murrah Federal Building in downtown Oklahoma City.  The explosion and partial collapse of the nine-story building killed 168 people and injured several hundreds more.  Exponent engineers worked with FEMA to assist in the rescue effort and determine how to safely remove debris from the remaining structure.  Structural engineers conducted on-site research to verify concepts used in designing blast resistant buildings and form the basis of a set of design principles called “defensive architecture” to minimize the loss of lives and property in the future.   Finally, to test the fertilizer alleged to have been used in the explosion, Exponent detonated a series of tests in the Arizona desert to investigate any potential explosive properties.
Sea Cliff Incident, San Francisco, CA
December 1995
In early December 1995, winter rains and construction activities combined to cause a major sewer pipe to fail in the prestigious Sea Cliff area of San Francisco.  This sudden and massive flow of water scoured soil from under several homes and streets.  One home was complete destroyed when it fell into the 250-foot wide by 40-foot deep pit created by the erosion.  An adjoining home was also damaged, but no one was injured.  Exponent investigators assisted the City of San Francisco in determining the cause of the sewer failures.  The findings, presented in a widely-distributed report and at several public meetings, indicated that cracks in the sewer developed when a series of events converged, including constriction of stormwater flow in the pipe and construction activities around the sewer.
August 1998
titanicOn August 3, 1998, Exponent provided expert witness testimony and demonstrative evidence support for the American Bar Association (ABA) Section of Litigation Mock Trial, “Litigating the Titanic: The Original and Greatest Disaster of This Century.” Exponent’s trial team utilized historically accurate information, line drawings obtained from Harland & Wolff, copies of ship blueprints and transcripts from hearings conducted immediately following the tragedy. Using this information, Exponent developed its theories regarding alleged design defects. Exponent employed sophisticated presentation technology to demonstrate the facts of the case as well as illustrate our theories. The mock trial was televised on Court TV (now TruTV).
Trunk Protection
At the request of a vehicle manufacturer, a project was conducted in which various devices were tested with young children to determine the one most likely to be used by them to escape from inside a vehicle’s trunk. Based on the testing, the lever-style handle was the device chosen for production. The project ultimately involved nearly 400 children, primarily ages three through six, and their parents who were present throughout the testing.
World Trade Center, New York, NY
September 11, 2001
wtcExponent's structural engineers supported the FEMA recovery and structural team efforts.  In the months following the disaster, Exponent was retained by the insurers of the WTC to provide a detailed analysis of the effects of the attack on the Twin Towers and surrounding buildings. Specifically, Exponent conducted a detailed study of the collapse and debris patterns for each tower and analyzed damage to the sub-grade mechanical, electrical and plumbing infrastructure to predict the effects of heavy and light debris impacts caused by the collapse of each tower. Our analysis included the effects of fire spread, smoke, and dust contamination and wind tunnel studies of the performance of the towers. 
American Airlines Flight 587
November 12, 2001
American Airlines flight 587 crashed into a residential area of Queens, New York, shortly after takeoff from JFK International Airport, when the vertical tail departed the aircraft. All 260 people aboard the airplane and five people on the ground perished, and the airplane was destroyed by impact forces and a post-crash fire. Exponent assisted with the investigation of the crash, including flight path reconstruction, evaluation of aerodynamic loads on the vertical tail of this aircraft during the crash, and aerodynamic loads on the tails of other aircraft during past in-flight upsets. Exponent also evaluated the rudder system design of the A300-605R against that of other aircraft, as well as the response of the A300-605R to various pilot and yaw damper inputs with various rudder system designs.
In the early days of the Iraq War, US Army soldiers on patrol had few options when encountering a potential roadside bomb. They could either call in an Explosive Ordnance Disposal (EOD) team with its specialized bomb-disposal robot, often waiting exposed on the roadside several hours for this specialized asset to arrive, or else take the very substantial risk of attempting to investigate the suspicious object manually.  Since its inception, Exponent had been forging a relationship with the US Army Rapid Equipping Force (REF). Working with their REF counterparts, Exponent engineers on the ground conceived of and prototyped a low-cost robot that could effectively perform the singular task of suspicious object investigation. Ultimately over 1000 production MARCbots were manufactured by Exponent for use in Iraq, and later, in Afghanistan. Among other innovations, the MARCbot was the first military robot to run exclusively on military supply chain batteries; years later this is now often a requirement for a robot that will be put into service by the Army. 
Unintended Acceleration in Toyota Vehicles
Beginning in 2009, Toyota was thrust into the national spotlight as a result of a NHTSA investigation into unintended acceleration of its vehicles. Consumers reported that their vehicles had rapidly accelerated without driver input, causing crashes, injuries, and fatalities. Regulators expressed concern regarding all-weather floor mats, accelerator pedals, electronics, software, and electromagnetic interference as potential causes of these events. In late 2009, Exponent was retained by Toyota to provide an independent investigation surrounding the incidents involving claims of sudden unintended acceleration. Exponent’s investigation concluded that the electronics, software, and electromagnetic radiation were not the root cause of the reported incidents of unintended acceleration in the Toyota vehicles evaluated. About a year later, in February 2011, two independent U.S. government agencies, NHTSA and NASA, found that there were no electronic or software problems to account for reports of sudden, unintended acceleration; these findings confirmed the results found by Exponent.
Deepwater Horizon
April 20, 2010
Following the April 20, 2010, Deepwater Horizon (DWH) accident, BP Exploration & Production Inc. and BP Gulf Coast Restoration Organization (BP) and federal and state governmental agencies engaged in one of the largest environmental data gathering efforts in history. Data were collected to guide efforts to respond to the accident (Response) and to assess potential damage to natural resources (Natural Resource Damage Assessment [NRDA]). Data were collected cooperatively and independently by BP and the agencies and stored in several discrete databases. To aid with data access and availability for researchers studying this DWH accident and other interested parties, BP envisioned a website to provide data integrated together in an easy to access format with links to the associated work plans and study descriptions. BP engaged Exponent to provide overall program management leadership, technical direction, and vision to a diverse team of consultants and project staff. The Gulf Science Data website was successfully launched in November 2013.
PG&E Explosion
September 9, 2010
A 30-inch diameter natural gas transmission pipeline (Line 132) owned and operated by Pacific Gas & Electric Company (PG&E) ruptured in a residential area in San Bruno, California. The explosion and fire destroyed 38 homes and damaged 70. Eight fatalities and numerous injuries and damage resulted from the explosion and fire. Exponent was retained by PG&E to perform a root cause analysis of the accident, examining records of operations and physical assets of Line 132; pipe specifications; gas flow data; pressure readings; historical purchase orders; interviews and testimony regarding the accident and third-party reports; and our own metallurgical analysis of the Line 132 pipe and specimens collected by the National Transportation Safety Board (NTSB). Exponent’s conclusion: no single factor led to the rupture — a unique combination of structural and metallurgical factors precipitated the tragedy.
Ground Penetrating Radar
IEDs (improvised explosive devices) were responsible for as many as 60% of the annual casualties experienced in Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF). For the U.S. Army, Exponent solved several challenging technology development and integration problems to rapidly develop a state-of-the-art ground penetrating radar (GPR) system for integration on a fielded military vehicle to aid in the detection of IEDs in Iraq and Afghanistan. The GPR system was a result of Exponent’s applied knowledge and experience with rapid development of leading military equipment, along with software and signal processing expertise. Working with several other companies, Exponent’s GPR system was integrated onto a SN2A Land Rover that was modified for remote control operation. This program took 11 months from kickoff to deployment to Afghanistan in early 2011. Exponent personnel supported both programs in theatre, modified any aspect of the system as required by evolving threats, trained soldiers to operate the systems, and performed major maintenance and logistics tasks.
Superstorm Sandy
October 20, 2012

Exponent’s engineers and scientists worked with a wide variety of affected commercial, government, and residential clients to evaluate structural damage, assess building envelopes, and assist with the recovery. Our team also evaluated electrical power systems for major agencies to help get facilities up and running quickly. Projects included high-value commercial complexes, transportation hubs, medical complexes, industrial facilities, and residential properties.
Hydraulic Fracturing
Exponent’s consultants have provided an integrated approach to all aspects of hydraulic fracturing operations, including: gas well drilling, completions, and operations; natural gas geochemistry; groundwater and surface water evaluation and treatment; and atmospheric sciences, state and federal regulatory support, geochemical and operational consulting, environmental forensics, chemical transport and fate, exposure assessment, dose reconstruction, and site specific human health risk assessment.
Oso Landslide
March 22, 2014
The collapse of a hillside triggered the single deadliest landslide event in United States history, engulfing 49 homes and killing 43 people in the Steelhead Haven community near the town of Oso, Washington. Exponent geological and civil engineers and hydrogeologists were called in to assess drainage and other potential contributing factors to the disaster, including forest harvesting and the plateau’s three distinct aquifers.
Wearable technologies — such as activity monitors, headsets, smart watches, smart clothing, and smart glasses — contain synthetic materials and electronic components that can have prolonged contact with skin under close conditions. Exponent has developed methods to assess dermal doses of sensitizing chemicals and estimate biocompatibility risks for the sensitized and general populations of users of these products. Exponent assists clients with customer skin reaction issues from wearable products — by identifying sensitizing chemicals and material sources in these products, by helping clients develop new biocompatible wearable products with prototype testing, and by offering guidance in finding substitute materials compatible with prolonged skin contact. 
Lumber Liquidators
On March 1, 2015: a CBS 60 Minutes investigation claimed that Lumber Liquidators sold laminate flooring from China with levels of formaldehyde, a volatile and carcinogenic toxin, higher than permitted under California law. Based on extensive testing of formaldehyde emissions from laminate flooring samples from homes and survey data on these residences, Exponent performed statistical modeling to determine possible exposure to customers with this product in their homes and associated acute and chronic health risks. The risk assessment was presented to the U.S. Consumer Product Safety Commission. For the typical installation, the risk assessment indicated that the Lumber Liquidators Chinese laminate could on average add about 20 ppb of formaldehyde to indoor air when installed, dropping to less than 5 ppb within 10 years — well below recognized levels of significant health concern.