Vanities of the Bonfire - Pushing the Limits: New Adventures in Engineering - page 119

Ray M. Bowen had announced the establishment of a commission “charged to initiate a review of
all aspects of the 1999 Aggie bonfire and to examine evidence developed by other investigations”
of the tragedy. The special commission was chaired by Leo Linbeck, Jr., a Houston construction
executive.
Within six months, the final report of the special commission was issued, and it revealed and ac-
knowledged officially design factors and patterns of behavior on the part of those participating in
Bonfire that contributed to the accident. The report shows the structural collapse to be a classic case
of design evolution and engineering hubris contributing to what in retrospect appears to have been
an accident waiting to happen. Bonfire tradition was to build on the successes of past years, but
modifications made from year to year negated what could be learned from experience. The builders
took the energy stored in a two-million-pound stack of logs a little too lightly, and they approached
the construction problem as if it were actually a piece of cake.
Even before the commission had begun its methodical study of the catastrophic failure, there
were theories about the collapse, as there are with any structural accident with so many fatalities and
such visibility. Among the prime early suspects was the tall center pole, which was made by splicing
two standard utility poles together along an elaborately fashioned lap joint. A Bonfire proper may
be said to have started with the raising of the center pole, which was buried as many as fifteen feet
in the ground and steadied by guylines anchored to other, outwardly inclined poles spaced around
the perimeter of the construction site. The use of a center pole was introduced in the mid-1940s,
when the configuration of the bonfire stack was conical, like a tepee, a shape achieved simply by
leaning logs against the center pole. The height of such an arrangement was limited by the length
of the logs used, but in the late 1950s a tepee Bonfire could reach a height of seventy feet. Such a
height required finding sufficiently long logs to lean against the pile, and it was their scarcity that
led in the 1960s to the development of the wedding-cake style of log stack.
The center pole serves not only as a symbolic axis for Bonfire but also enables the use of block
and tackle to assist in raising logs and workers as the stack rises. The 1999 Bonfire stack had
reached about forty-five feet up the center pole when the accident occurred. Students who witnessed
the collapse reported that they noticed the stack begin to shift and then heard a loud crack, followed
by the collapse of the incomplete structure. Some observers interpreted this sequence of events as
pointing to the fracture of the center pole as the initiator of the fatal event. However, after a struc-
tural analysis, the commission found that “given the enormous weight of the stack, even a perfect
center pole could not have played a significant role in providing structural strength.” In other words,
for all its symbolic function, the center pole had never supported the stacks of logs piled around it,
and so another cause had to be found.
The soil on which Bonfire was built had also been an early suspect in the collapse. This seemed
to provide a credible explanation, given the fact that in 1994 soil softened by rain was identified as
the reason that the pile of logs fell over just two weeks before the big football game. However, the
fall of 1999 was not as wet as that of 1994, and, as reported by the special commission, “analysis
showed the soil to be sufficiently compact and stable and that it could easily support a structure at
least twice as heavy.”