World Trade Center Investigation

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</li> <li> <a href="/web/20220414201357/https://www.nist.gov/nist-museum" class="usa-nav__link">NIST Museum</a> </li> <li> <a href="/web/20220414201357/https://www.nist.gov/nist-and-nobel" class="usa-nav__link">NIST and the Nobel</a> </li> </ul> </li> <li class="usa-nav__submenu-item"> <a href="/web/20220414201357/https://www.nist.gov/education" class="usa-nav__link">Resources for Kids</a> </li> </ul> </div> </div> </div> </li> </ul> </div> </nav> </header>  <div class="grid-container"> <div data-drupal-messages-fallback class="hidden"></div> </div> <div id="block-nist-www-content" class="nist-block"> <section class="nist-page__content usa-section clearfix"> <a id="main-content" tabindex="-1"></a> <div> <div class="nist-section-header nist-section-header--topic nist-section-header--hero"> <div class="nist-section-header__top grid-container"> <a href="/web/20220414201357/https://www.nist.gov/resilience">Resilience</a> /<a href="/web/20220414201357/https://www.nist.gov/disaster-failure-studies">Disaster & failure studies</a> </div> <div class="nist-section-header__sub"> <div class="nist-section-header__main grid-container"> <div class="grid-row"> <div class="nist-section-header__title"> <h1 class="nist-page__title">World Trade Center Investigation</h1> </div> </div> </div> </div> </div> </div> <div class="grid-container"> <div class="nist-page__region nist-page__region--topic-description padding-top-4 margin-top-1"> <div class="nist-region-heading"> <h2>Overview</h2> </div> <div class="grid-row"> <div class="tablet:grid-col-8 padding-right-5 margin-bottom-4"> <div class="text-with-summary"> <p>The collapse of the WTC buildings following the terrorist attacks on September 11, 2001, was one of the worst building disasters in US history, killing 2,749 people, including 400 emergency responders.</p> <p>NIST responded to calls from Congress and the public to carry out a federal investigation of why the buildings collapsed, the evacuation of building occupants and the emergency response. NIST was given this authority when Congress passed, and the President signed into law, the <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="5fb3533c-d394-4b91-aa2c-eeee11e845c3" href="/web/20220414201357/https://www.nist.gov/disaster-failure-studies/national-construction-safety-team-ncst" title="About the National Construction Safety Team (NCST) Act">National Construction Safety Team Act</a> of 2002. </p> <p>More than 200 professionals and technical subject matter experts, including 85 NIST staff members, answered the call and participated in the investigation.</p> <p>As part of the investigation, the NIST team gathered every bit of evidence they could find. Activities included:</p> <ul><li>Interviews with 1,056 surviving occupants of the WTC buildings and 116 emergency responders.</li> <li>Extensive reviews of design, construction, maintenance and inspection documents for the buildings </li> <li>Examination of hundreds of structural steel components from WTC buildings</li> <li>Gathering and analyzing thousands of pieces of video, photographic, and audio evidence from professional sources and the public</li> </ul><figure class="align-center nist-video" data-media-id="621841"><div class="video-embed-field"><div class="video-embed-field-lazy" data-video-embed-field-lazy="<div class="video-embed-field-provider-nist-kaltura video-embed-field-responsive-video"><iframe width="854" height="480" frameborder="0" allow="autoplay *; fullscreen *; encrypted-media *" allowfullscreen="allowfullscreen" src="https://www.kaltura.com/p/684682/sp/68468200/embedIframeJs/uiconf_id/31013851/partner_id/684682?iframeembed=true&amp;entry_id=1_nxs2rwl1?iframeembed=true&amp;entry_id=1_nxs2rwl1&amp;flashvars%5BautoPlay%5D=1"></iframe> </div> "><img alt="NIST's World Trade Center Investigations" src="https://web.archive.org/web/20220414201357im_/https://cdnsecakmi.kaltura.com/p/684682/sp/68468200/thumbnail/entry_id/1_nxs2rwl1/width/1280" typeof="foaf:Image"/><button class="video-embed-field-lazy-play"></button> <div class="video-embed-field-lazy-title">NIST's World Trade Center Investigations</div> </div> </div> <figcaption class="nist-video__caption" data-caption-editable="true"> Learn more about NIST's work on the World Trade Center investigations, from how it conducted the study to the recommendations and their lasting legacy. </figcaption></figure> </div> </div> <div class="tablet:grid-col-4"> <div class="nist-block nist-block--no-margin"> <h2 class="nist-block__title">Featured Content</h2> <div class="nist-field nist-field--label-hidden nist-field--link-list link font-sans-sm"> <div class="nist-field__items"> <div class="nist-field__item"><a href="/web/20220414201357/https://www.nist.gov/world-trade-center-investigation/about-investigation">About the Investigation</a></div> <div class="nist-field__item"><a href="/web/20220414201357/https://www.nist.gov/world-trade-center-investigation/study-faqs">Study FAQs</a></div> <div class="nist-field__item"><a href="/web/20220414201357/https://www.nist.gov/world-trade-center-investigation/investigation-meetings-and-presentations">Investigation Meetings</a></div> <div class="nist-field__item"><a href="/web/20220414201357/https://www.nist.gov/world-trade-center-investigation/news-archive">News Archive</a></div> <div class="nist-field__item"><a href="/web/20220414201357/https://www.nist.gov/world-trade-center-investigation/photos-videos-and-simulations">Photos, Videos and Simulations</a></div> <div class="nist-field__item"><a href="/web/20220414201357/https://www.nist.gov/world-trade-center-investigation/publications-and-reports">Publications and Reports</a></div> <div class="nist-field__item"><a href="/web/20220414201357/https://www.nist.gov/world-trade-center-investigation/recommendations">Recommendations</a></div> <div class="nist-field__item"><a href="/web/20220414201357/https://www.nist.gov/disaster-failure-studies/data-archive">Disaster and Failure Studies Repository</a></div> </div> </div> </div> </div> </div> </div> </div> <div class="nist-page__region nist-page__region--main"> <div class="nist-block"> <div class="grid-container margin-y-5"> <div class="paragraph paragraph--type--topic-text paragraph--view-mode--default"> <div class="nist-region-heading"> <h2> The Reports </h2> </div> <div class="tablet-lg:grid-col-8 padding-right-5"> <div class="text-long"><p>Throughout the process, NIST held <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="387e56b9-1527-46ac-970a-724d7976045f" href="/web/20220414201357/https://www.nist.gov/world-trade-center-investigation/investigation-meetings-and-presentations" title="WTC Investigation Meetings and Presentations">23 public meetings</a> and provided multiple opportunities for the public to review and comment on drafts of the reports. In addition, all of the reports were reviewed by an external, non-NIST NCST advisory committee.</p> <p>In the end, NIST released final versions of the <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="722a78f4-45d2-4e90-a03a-63384bae3dc0" href="/web/20220414201357/https://www.nist.gov/world-trade-center-investigation/publications-and-reports" title="World Trade Center Disaster Study Reports and Other Publications">43 reports</a> on the WTC towers, totaling some 10,000 pages, on October 26, 2005. NIST released final versions of the <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="722a78f4-45d2-4e90-a03a-63384bae3dc0" href="/web/20220414201357/https://www.nist.gov/world-trade-center-investigation/publications-and-reports" title="World Trade Center Disaster Study Reports and Other Publications">three reports</a> on WTC 7, totaling about 1,000 pages, on November 25, 2008.</p> <p>NIST is aware of other studies related to the WTC collapse and stands by its original findings. </p></div> </div> </div> </div> <div class="paragraph paragraph--type--topic-featured paragraph--view-mode--default nist-content-row--width-full bg-base-lightest margin-y-5"> <div class="grid-container"> <div class="nist-card nist-card--horizontal nist-card--horizontal-full nist-card--base-lightest"> <div class="nist-card__inner"> <div class="nist-card__image"> <div class="entity-reference"> <figure class="nist-image"> <img src="/web/20220414201357im_/https://www.nist.gov/sites/default/files/styles/800w_x_400h/public/images/2021/08/16/WTC-style_Sunder2_0.jpg?itok=E5px970k" width="800" height="400" alt="collage showing rubble from the collapse of the towers, a mock up of a section of the towers, scientists looking at structural steel and the words Building and Fire Codes" loading="lazy" typeof="foaf:Image"/> <figcaption class="nist-image__caption"> <div data-caption-editable="true" class="nist-image__caption-content"> </div> </figcaption> </figure> </div> </div> <div class="nist-card__title"> <h3> 20 Years Later: NIST's World Trade Center Investigation and Its Legacy </h3> </div> <div class="nist-card__content"> <div class="text-long"><p>Read first-hand accounts of what it was like to work on the WTC investigation in our blog series. </p> <p>Start with Shyam Sunder's reflections on the investigation and its legacy, and then keep reading for insights on everything from <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="bc640b8c-f2b3-4370-afb2-56875739e13d" href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/putting-together-big-picture-world-trade-center-disaster-investigation" title="Putting Together the Big Picture for the World Trade Center Disaster Investigation">what it was like to catalogue the images and video</a> to <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="a90b3d95-1afe-4af8-8bdd-97ef9dc2ed69" href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/how-911-changed-me-and-first-responder-communications" title="How 9/11 Changed Me and First Responder Communications">how 9-11 changed one researcher... and first responder communications</a>.</p></div> </div> <div class="nist-card__links"> <div class="nist-card__button"> <a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/20-years-later-nists-world-trade-center-investigation-and-its-legacy" class="usa-button ">Read the blog post from Shyam Sunder</a> </div> </div> </div> </div> </div> </div> <div class="grid-container margin-y-5"> <div class="paragraph paragraph--type--topic-text paragraph--view-mode--default"> <div class="nist-region-heading"> <h2> The Legacy </h2> </div> <div class="tablet-lg:grid-col-8 padding-right-5"> <div class="text-long"><h3>Building and Fire Codes, Standards and Practices</h3> <p>The WTC investigation has had a significant legacy. In the reports, NIST made 31 recommendations for improvements to building and fire codes, standards, and practices based on the WTC investigation. While the federal government has no regulatory authority for building and fire codes, many U.S. codes and standards were subsequently updated to improve areas such as structural integrity, fire resistance, occupant evacuation and emergency responder communications. NIST’s recommendations have had a significant impact on design and construction practices for high-rise buildings worldwide, including the new buildings at the rebuilt World Trade Center site. </p> <p>In addition, NIST scientists conducted tests of steel from the WTC buildings to measure their mechanical properties at normal and elevated temperatures. These tests led to the development and validation of performance criteria for fire resistive steel. This type of steel, which was not available at the time the WTC was built, would not necessarily prevent a building from collapsing during a fire, but it would give occupants more time to escape. </p> <div class="usa-alert usa-alert--info usa-alert--slim usa-alert--no-icon"> <div class="usa-alert__body"> <p class="usa-alert__text">Read <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="80f68777-735f-40f8-afc0-6e39d8537bbc" href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/inside-towers-911-my-story-investigating-wtc-evacuation" title="Inside the Towers on 9/11: My Story of Investigating the WTC Evacuation">Jason Averill's story</a> about investigating the WTC evacuation and <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="4e10f09c-87f9-440c-b7ee-6961e27d5ba0" href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/analyzing-aftermath-twin-towers-aircraft-impacts" title="Analyzing the Aftermath of the Twin Towers Aircraft Impacts">Steve Kirkpatrick's work</a> analyzing the aftermath of the Twin Towers aircraft impacts.</p> </div> </div> <h3>DNA Identification</h3> <p>NIST also played a role in the effort to identify the victims of the 9/11 attack. This effort was at the time — and still is — the largest forensic identification effort ever undertaken. This effort was particularly challenging because in many cases the DNA of the victims was severely degraded by exposure to intense heat from burning jet fuel, as well as moisture and decay in the weeks and months following the attack. To make an identification, experts analyzed segments of DNA called forensic markers. When DNA degrades, these forensic markers break apart, which makes them difficult to analyze.</p> <p>To cope with this challenge, researchers at NIST, Ohio University and Bode Technology developed new forensic markers involving shorter segments of DNA, which by virtue of their small size are more likely to remain intact as the DNA degrades. This effort allowed forensic experts to identify thousands of remains that otherwise would have never been returned to their families. The research conducted at NIST in the aftermath of 9/11 led to the development of new “mini-markers” that are now routinely used in criminal casework. These markers have helped investigators solve countless sexual assaults, homicides and other crimes that would otherwise have gone cold.</p> <div class="usa-alert usa-alert--info usa-alert--slim usa-alert--no-icon"> <div class="usa-alert__body"> <p class="usa-alert__text">Read <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="5191d0f8-a8dc-4838-8e92-f8342861b4f9" href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/reflections-assisting-911-world-trade-center-dna-identifications" title="Reflections on Assisting With the 9/11 World Trade Center DNA Identifications">John Butler's reflections</a> on assisting with the 9/11 World Trade Center DNA identifications.</p> </div> </div> <h3>Public Safety Communications</h3> <p>Among the victims were more than 400 first responders, including firefighters, police officers, and Port Authority officers. These deaths revealed a huge gap in public safety communications and fundamentally changed NIST’s research focus in public safety communications. During the disaster, first responders struggled to communicate due to lack of interoperability among the radio systems and over-crowded communication channels. As a result, the 9/11 Commission made communications research for public safety a priority, and tasked NIST with finding solutions.</p> <p>NIST established its <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="b13e7096-e337-49c7-a330-2856498550cf" href="/web/20220414201357/https://www.nist.gov/ctl/pscr" title="Public Safety Communications Research Division">Public Safety Communications Research division</a> and became a technical advisor to Congress and the White House on issues surrounding public safety communications. This new research focus helped established FirstNet, a nationwide broadband network dedicated to first responder communications. In the 20 years since the attacks, NIST and its partnering research organizations and industry have resolved many of the radio interoperability issues and now focus on modernizing communications technology for first responders.</p> <div class="usa-alert usa-alert--info usa-alert--slim usa-alert--no-icon"> <div class="usa-alert__body"> <p class="usa-alert__text">Read <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="a90b3d95-1afe-4af8-8bdd-97ef9dc2ed69" href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/how-911-changed-me-and-first-responder-communications" title="How 9/11 Changed Me and First Responder Communications">Dereck Orr's reflections</a> on how 9-11 changed him, and public safety communications.</p> </div> </div> <h3>National Fire Research Laboratory & Disaster Resilience Program</h3> <p>As a result of the WTC investigation, NIST established the <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="4afd0612-592b-4335-8d3e-93d1ec5578d5" href="/web/20220414201357/https://www.nist.gov/el/fire-research-division-73300/national-fire-research-laboratory-73306" title="National Fire Research Laboratory">National Fire Research Laboratory</a>, which has provided a unique capability to test performance of large-scale structures under realistic conditions. NIST also established a Disaster Resilience Program, focused on ways to improve the safety and resilience of buildings and communities in the face of multiple threats including wildfires, hurricanes, tornadoes and earthquakes. Improving resilience has emerged as a major theme of the 21st century, and the NCST Act, created in response to 9/11, has enabled NIST to conduct technical investigations of subsequent significant disasters. including the <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="be21f48d-b9b4-482d-b2db-1cc91f14fb46" href="/web/20220414201357/https://www.nist.gov/disaster-failure-studies/joplin-tornado-ncst-investigation" title="Joplin Missouri Tornado 2011">Joplin, Missouri, tornado</a> in May 2011; the <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="04c3ec62-8d0c-4a6c-b8ba-8aae45fab27d" href="/web/20220414201357/https://www.nist.gov/disaster-failure-studies/station-nightclub-fire-ncst-investigation" title="The Station Nightclub Fire 2003">2003 Station nightclub fire</a> in West Warwick, Rhode Island; the effects of 2017’s <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="682765ce-795f-4dca-9d0e-7c6085cf27c7" href="/web/20220414201357/https://www.nist.gov/disaster-failure-studies/hurricane-maria-program" title="Hurricane Maria">Hurricane Maria</a> on Puerto Rico and, most recently, the <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="ea7045d8-7824-4369-b3d3-167935b16bf7" href="/web/20220414201357/https://www.nist.gov/disaster-failure-studies/champlain-towers-south-collapse-ncst-investigation" title="Champlain Towers South Collapse">Champlain Towers Collapse</a> in Miami, Florida, in June 2021.</p></div> </div> </div> </div> <div class="grid-container margin-y-5"> <div class="paragraph paragraph--type--topic-text paragraph--view-mode--default"> <div class="nist-region-heading"> <h2> Blogs </h2> </div> <div class="tablet-lg:grid-col-8 padding-right-5"> <div class="text-long"><div data-embed-button="block" data-entity-embed-display="view_mode:block_content.full" data-entity-type="block_content" data-entity-uuid="2ca56768-5a92-4f62-8c2a-3384f3815675" data-langcode="en" class="embedded-entity"> <div class="viewsreference"><div class="views-element-container"><div class="js-view-dom-id-1f560d31c3bbc56fcdc3740bd4144c9d9304b45ec2d15ba9bbed4ee1b85189bd"> <div> <article role="article" about="/blogs/taking-measure/reconstructing-fires-brought-down-wtc-1-2-and-7" class="nist-teaser"><div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/reconstructing-fires-brought-down-wtc-1-2-and-7" hreflang="en"><img src="/web/20220414201357im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2021/08/12/WTC-style-Gann.jpg?itok=bDECOBna" width="100" height="63" alt="collage of blueprints for buildings and an airplane, a pile of rubble, a live fire test of a simulated office, and the word Reconstruction" loading="lazy" typeof="foaf:Image"/></a> </div> </div> <div class="nist-teaser__content-wrapper"> <header><h3 class="nist-teaser__title"><a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/reconstructing-fires-brought-down-wtc-1-2-and-7"><span>Reconstructing the Fires That Brought Down WTC 1, 2 and 7</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2021-09-08T12:00:00Z">September 8, 2021</time></div> </div> </header><div class="nist-teaser__content"> <div class="text-with-summary">Everyone has a story about where they were when they heard about the disaster universally called “9/11.” Mine begins in Ottawa, Canada. As chance would have it</div> </div> </div> </article></div> <div> <article role="article" about="/blogs/taking-measure/inside-towers-911-my-story-investigating-wtc-evacuation" class="nist-teaser"><div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/inside-towers-911-my-story-investigating-wtc-evacuation" hreflang="en"><img src="/web/20220414201357im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2021/08/17/WTC-style-Averill.jpg?itok=Ko1ui7Kj" width="100" height="63" alt="a collage showing images of a crowd of people, an elevator, the word evacuation, a stairwell with the stairs marked as 1.5 meters wide, an icon of a telephone with the numbers 911, and a camera" loading="lazy" typeof="foaf:Image"/></a> </div> </div> <div class="nist-teaser__content-wrapper"> <header><h3 class="nist-teaser__title"><a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/inside-towers-911-my-story-investigating-wtc-evacuation"><span>Inside the Towers on 9/11: My Story of Investigating the WTC Evacuation</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2021-09-03T12:00:00Z">September 3, 2021</time></div> </div> </header><div class="nist-teaser__content"> <div class="text-with-summary">The kickoff meeting On Nov. 1, 2002, in a small conference room on the Gaithersburg, Maryland, campus of the National Institute of Standards and Technology</div> </div> </div> </article></div> <div> <article role="article" about="/blogs/taking-measure/reflections-assisting-911-world-trade-center-dna-identifications" class="nist-teaser"><div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/reflections-assisting-911-world-trade-center-dna-identifications" hreflang="en"><img src="/web/20220414201357im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2021/08/12/WTC-style-JohnButler.jpg?itok=C4_aDhhP" width="100" height="63" alt="collage of images from the WTC disaster and the NYC skyline with a representation of a DNA molecule and the letters DNA, " loading="lazy" typeof="foaf:Image"/></a> </div> </div> <div class="nist-teaser__content-wrapper"> <header><h3 class="nist-teaser__title"><a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/reflections-assisting-911-world-trade-center-dna-identifications"><span>Reflections on Assisting With the 9/11 World Trade Center DNA Identifications</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2021-09-01T12:00:00Z">September 1, 2021</time></div> </div> </header><div class="nist-teaser__content"> <div class="text-with-summary">On Tuesday, Sept. 11, 2001, I walked to work from my home in Olde Towne Gaithersburg, Maryland, and arrived at my office shortly before 9 a.m. I had just</div> </div> </div> </article></div> <div> <article role="article" about="/blogs/taking-measure/analyzing-aftermath-twin-towers-aircraft-impacts" class="nist-teaser"><div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/analyzing-aftermath-twin-towers-aircraft-impacts" hreflang="en"><img src="/web/20220414201357im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2021/08/12/WTC-style_kirkpatrick.jpg?itok=yJTb0-zZ" width="100" height="63" alt="collage of images from the WTC disaster, a blueprint of an airplane, a representation of one of the towers, the word modeling" loading="lazy" typeof="foaf:Image"/></a> </div> </div> <div class="nist-teaser__content-wrapper"> <header><h3 class="nist-teaser__title"><a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/analyzing-aftermath-twin-towers-aircraft-impacts"><span>Analyzing the Aftermath of the Twin Towers Aircraft Impacts</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2021-08-27T12:00:00Z">August 27, 2021</time></div> </div> </header><div class="nist-teaser__content"> <div class="text-with-summary">I consider myself lucky to have been able to perform contract engineering research and consulting for my entire career. The work environment has been somewhere</div> </div> </div> </article></div> <div> <article role="article" about="/blogs/taking-measure/putting-together-big-picture-world-trade-center-disaster-investigation" class="nist-teaser"><div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/putting-together-big-picture-world-trade-center-disaster-investigation" hreflang="en"><img src="/web/20220414201357im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2021/08/12/WTC-style_KathyButler.jpg?itok=yGqLEwS4" width="100" height="63" alt="collage of images of the 9/11 disaster, some are shaped like puzzle pieces, there is a representation of frames of film" loading="lazy" typeof="foaf:Image"/></a> </div> </div> <div class="nist-teaser__content-wrapper"> <header><h3 class="nist-teaser__title"><a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/putting-together-big-picture-world-trade-center-disaster-investigation"><span>Putting Together the Big Picture for the World Trade Center Disaster Investigation</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2021-08-25T12:00:00Z">August 25, 2021</time></div> </div> </header><div class="nist-teaser__content"> <div class="text-with-summary">Imagine assembling a jigsaw puzzle of more than 14,000 pieces without an image on the box showing what the final picture will look like. Imagine that important</div> </div> </div> </article></div> <div> <article role="article" about="/blogs/taking-measure/how-911-changed-me-and-first-responder-communications" class="nist-teaser"><div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/how-911-changed-me-and-first-responder-communications" hreflang="en"><img src="/web/20220414201357im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2021/08/12/WTC-style_Orr.jpg?itok=j63YK6jv" width="100" height="63" alt="a collage including images of a radio tower, a handheld radio, a fire engine, and the word Connection" loading="lazy" typeof="foaf:Image"/></a> </div> </div> <div class="nist-teaser__content-wrapper"> <header><h3 class="nist-teaser__title"><a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/how-911-changed-me-and-first-responder-communications"><span>How 9/11 Changed Me and First Responder Communications</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2021-08-20T12:00:00Z">August 20, 2021</time></div> </div> </header><div class="nist-teaser__content"> <div class="text-with-summary">If you remember Sept. 11, 2001, that day is most likely imprinted on your mind like no other day. You remember what you were doing and who you were with. You</div> </div> </div> </article></div> <div> <article role="article" about="/blogs/taking-measure/20-years-later-nists-world-trade-center-investigation-and-its-legacy" class="nist-teaser"><div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/20-years-later-nists-world-trade-center-investigation-and-its-legacy" hreflang="en"><img src="/web/20220414201357im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2021/08/16/WTC-style_Sunder2_0.jpg?itok=X7gm6cJv" width="100" height="63" alt="collage showing rubble from the collapse of the towers, a mock up of a section of the towers, scientists looking at structural steel and the words Building and Fire Codes" loading="lazy" typeof="foaf:Image"/></a> </div> </div> <div class="nist-teaser__content-wrapper"> <header><h3 class="nist-teaser__title"><a href="/web/20220414201357/https://www.nist.gov/blogs/taking-measure/20-years-later-nists-world-trade-center-investigation-and-its-legacy"><span>20 Years Later: NIST's World Trade Center Investigation and Its Legacy</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2021-08-18T12:00:00Z">August 18, 2021</time></div> </div> </header><div class="nist-teaser__content"> <div class="text-with-summary">The collapse of the World Trade Center (WTC) buildings following the terrorist attacks of Sept. 11, 2001, was one of the worst-ever building disasters in</div> </div> </div> </article></div> </div> </div> </div> </div> </div> </div> </div> </div> </div> </div> </section> </div>  <footer class="nist-footer padding-bottom-4"> <div class="grid-container nist-footer__info"> <div class="grid-row"> <div class="tablet:grid-col-6"> <div class="nist-footer__logo"> <a href="/web/20220414201357/https://www.nist.gov/" title="National Institute of Standards and Technology" rel="home"> <img class="nist-footer__logo-img" src="/web/20220414201357im_/https://www.nist.gov/libraries/nist-component-library/dist/img/logo/nist_logo_sidestack_rev.svg" alt="National Institute of Standards and Technology logo"> </a> </div> <div class="nist-footer__contact"> <h3 class="nist-footer__contact-heading">HEADQUARTERS</h3> <address> 100 Bureau Drive<br> Gaithersburg, MD 20899<br> <a href="https://web.archive.org/web/20220414201357/tel:301-975-2000">301-975-2000</a> </address> <p> <a href="https://web.archive.org/web/20220414201357/mailto:do-webmaster@nist.gov">Webmaster</a> | <a href="https://web.archive.org/web/20220414201357/https://www.nist.gov/about-nist/contact-us">Contact Us</a> | <a href="https://web.archive.org/web/20220414201357/https://www.nist.gov/visit">Our Other Offices</a> </p> </div> </div> <div class="tablet:grid-col-6"> <div class="nist-footer__social-links"> <a class="nist-social nist-social--twitter-white" href="https://web.archive.org/web/20220414201357/https://twitter.com/NIST"> <span>Twitter</span> </a> <a class="nist-social nist-social--facebook-white" href="https://web.archive.org/web/20220414201357/https://www.facebook.com/NIST"> <span>Facebook</span> </a> <a class="nist-social nist-social--linkedin-white" href="https://web.archive.org/web/20220414201357/https://www.linkedin.com/company/nist"> <span>LinkedIn</span> </a> <a class="nist-social nist-social--instagram-white" href="https://web.archive.org/web/20220414201357/https://www.instagram.com/nist/"> <span>Instagram</span> </a> <a class="nist-social nist-social--youtube-white" href="https://web.archive.org/web/20220414201357/https://www.youtube.com/NIST"> <span>YouTube</span> </a> <a class="nist-social nist-social--giphy-white" href="https://web.archive.org/web/20220414201357/https://giphy.com/nist"> <span>Giphy</span> </a> <a class="nist-social nist-social--rss-white" href="https://web.archive.org/web/20220414201357/https://www.nist.gov/news-events/nist-rss-feeds"> <span>RSS Feed</span> </a> <a class="nist-social nist-social--envelope-white" href="https://web.archive.org/web/20220414201357/https://service.govdelivery.com/accounts/USNIST/subscriber/new"> <span>Mailing List</span> </a> </div> <div class="nist-footer__feedback"> How are we doing? 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