https://www.abc.net.au/news/2021-09-10/ ... /100436856
For those who survived the initial impact of two passenger jets that slammed into the World Trade Centre on September 11, 2001, the nightmare was just beginning.
The simplest of escape routes were the stairwells.
To get out of the world's then-tallest buildings, you had to take 2,071 steps to descend from the highest floor.
But as they desperately tried to flee the smoke and flames, some found themselves trapped in stifling, overcrowded stairwells, descending at an agonising pace.
"Once we hit [floor] 69, it was just ... a step a minute," survivor Arthur Lee would later recall.
The stairwells became a bottleneck as people trying to escape squeezed past firefighters running up towards the point of impact.
Hundreds of Americans on 9/11 who survived the initial impacts from the two hijacked aircraft perished for want of a safe exit.
The stairwells were a critical factor in the death toll that day. There were too few, too close together and with walls too weak to withstand the fire.
That nightmare scenario has furiously driven safety experts for the past two decades to push for vital changes to US building safety codes.
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