Harold E. Nelson

Federal Investigation of the Evacuation of the World Trade Center on September 11, 2001.

This paper presents the findings of the NIST World Trade Center Investigation describing the occupant evacuation of WTC 1 and WTC 2 on September 11, 2001. The egress system, including stairwells and elevators, is described along with the evacuation procedures. The population in WTC 1 and WTC 2 on September 11, 2001 at 8:46 a.m. is enumerated and described, where the background of the population was relevant to the subsequent evacuation, including training, experience, mobility status, among others. The progress of the evacuation of both towers is described in a quasi-chronological manner. A decedent analysis explores where occupants were located when each tower was attacked. Multiple regression models were built to explore the sources of evacuation initiation delay (why people did not immediately start to leave the building), as well as stairwell evacuation time (how long the average occupant spent in the stairwells per floor). Issues identified as contributing to either slowing or aiding the evacuation process were explored. Egress simulations provided context for estimating how long WTC 1 and WTC 2 would have taken to evacuate with different populations, using three different models, and subject to different assumptions of damage to the building.

Radiant energy transfer in fire protection engineering problem solving

The author develops a mode of radiant energy transfer for rectangular surfaces, regardless of size, and presents it in terms of configuration factor developed from graphic presentations that avoid cumbersome mathematics.

A systems analysis of the energy environment in buildings

The author has derived a flow diagram of fire development in order to point out areas where current technology can be applied to the fire problem as well as areas where further research is required.

Room fires as a design determinant

Potential fire intensity and fire spread are acknowledged to be important considerations in designing buildings. Most investigations in this area have attempted to relate fire intensity to fuel load. The author submits that room geometry and influence fire intensity and that architectural layouts around room openings may influence fire spread by means of convestion.