The World Trade Center Attacks and the Need for Exit Path Markings

In the 1993, the World Trade Center bombing redefined the importance of photoluminescent egress path markings in vertical exit enclosures. Terrorists parked a bomb-laden truck under the World Trade Center’s North Tower. When the bomb exploded, it destroyed the towers’ emergency power supply system, rendering the backup lighting in their vertical exit enclosures inoperable. Consequently, thousands of building occupants evacuated in the dark; a scenario that could have caused fatalities if a fire had been present.

Improvements in vertical exit enclosures

Following the failure of the World Trade Center’s backup lighting, the Port Authority installed photoluminescent markings in its vertical exit enclosures, a move that prompted cities and states to mandate the placement of luminescent exit path markings in vertical exit enclosures, particularly on:

  • handrails and handrail extensions,
  • the leading edges of steps and landings,
  • the perimeter of landing areas,
  • egress path obstacles, and
  • the doorframes and door hardware of exit-leading doors.

Today, most building owners implement luminescent markings in accordance with the International Building Code (IBC) and the International Fire Code (IFC), which regulate construction quality, structural stability, life safety, and fire safety in commercial and residential R1 buildings that feature occupancy above 75 feet from the lowest level of fire department vehicle access. When implemented according to IBC and IFC guidelines, egress markings illuminate the equipment and dimensions of vertical exit enclosures, making them visible in the dark, even in the presence of smoke.

The impact of the September 11, 2001 terrorist attacks

If the 1993 World Trade Center bombing solidified the importance of luminescent markings in exit enclosures, the terrorist attacks of September 11, 2001 brought the opportunity to assess the importance of photoluminescent egress path markings on evacuation time. In a recent interdisciplinary study by researchers from the Mailman School of Public Health at Columbia University in New York City, 1,444 people who evacuated from the World Trade Center following the 2001 terrorist attacks were questioned about factors that influenced their evacuation time.

Concerning individual evacuation time, one of the primary influencers was the availability of visual cues. When strong visual cues were not present, the respondents felt their evacuation time was increased. According to a 2009 study by the National Institute for Standards and Technology (NIST), the behavior of evacuees has a significant impact on evacuation time. Considering this finding in light of the finding from the Mailman School of Public Health study, one can see the importance of providing evacuees with as many visual cues as possible, and this is what luminous exit path markings and signage do.

Buying the best luminescent egress products

At Jessup manufacturing, we have years of experience creating luminescent technology that helps evacuees exit buildings in a smooth, timely manner. If your building’s vertical exit enclosures are without IBC and IFC compliant egress path markings and signage, contact us today to learn how our patented Glo Brite technology can impact evacuation time. Without luminescent markings and signage as reference points, your building occupants could become like the 1993 World Trade Center evacuees, trying to escape from danger in the dark.

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