down, except for two deviations in stairwells A and C where the staircase jut-
ted out toward the perimeter of the building. On the upper and lower bound-
aries of these deviations were transfer hallways contained within the stairwell
proper. Each hallway contained smoke doors to prevent smoke from rising from
lower to upper portions of the building; they were kept closed but not locked.
Doors leading from tenant space into the stairwells were never kept locked;
reentry from the stairwells was generally possible on at least every fourth floor.
and cluttered surfaces with radiation hazards, making them impractical for hel-
icopter landings and as staging areas for civilians. Although the South Tower
roof had a helipad, it did not meet 1994 Federal Aviation Administration
guidelines.
Response.