Page 18 - Wire Rope News & Sling Technology - June 2019
P. 18

Tower Crane Safety,

                      Then and Now – a History

                                               by Dennis J O’Rourke CSP
         The manuals/magazines I read, articles that are written by leaders in this field, and
         my experience have caused me to change some of my conclusions and nudged
         me to research tower crane accidents further. I hope to benefit the reader by
         sharing how I have augmented my work practices.
                                                                                 Fig. 2: Construction of Lakhta
                                                                                 Center in St. Petersburg, Russia.
              HE PAST                       crane soaring above a high rise build-  Photo ©BackyardProduction | iStockphoto.
              Hoisting  equipment  has  been   ing under construction. As humankind
         Tplaced on “towers” to raise materi-  multiplied, so did the need for taller
         als for centuries. The first towers were   buildings to keep pace with the cities’
         the very structure that was under con-  growth  –  simple  as  that.  Cranes  rose
         struction. In a model (Figure 1) we see   higher, and higher, and still higher!
         a beam supported by a building, and   One  of  the  tallest buildings  in  East-
         its “upper block” at the end, and the   ern Europe, St. Petersburg, Russia, is
         rope is attached to a load. The line goes   about 1500 feet (462m) tall and built
         down to a “lower block,” secured to the   with external free-standing tower
         ground, then tied to a horse that walks   cranes. (Figure 2)
         out and pulls the weight up to a carpen-  There  is  a very  logical  reason  for
         ter standing on the roof, truly one horse-  building “up and not out.” First, it is a
         power! The hazards and exposures here   more efficient use of the land and utili-
         are the same as they are today.    ties. Take this one building, for exam-
           My  first  memory  of  a  tower  crane   ple: a 1500 foot sewer pipe, top to bot-
         was a trailer mounted, all manually   tom, can remove the wastewater from
         operated, self-erecting, located in Ire-  more than 350 apartments. The length
         land.  I  observed  it  when  on  a  1960s   of the sewer pipes connecting 350 pri-
         vacation. It was helping build a two-  vate home extending over 70 acres (5
         story house. Working at Port Canav-  per acre) would equal miles of the stuff,
         eral at the time, cranes interested me   plus all the roads, walks, cables, etc.
         – I maintained them.                 Another advantage of going up is en-
           The  description  “tower  crane”  is  a   vironmental – save the trees; they ab-
         relatively modern term for the rotating   sorb carbon dioxide.
                                              Leaving large tracks of rural un-
                                            spoiled land is  now  a priority  man-
                                            dated by some states. Today, trees are
                                            looked upon as preferred to be living.
                                            And they are not taken for granted;
                                            they allow humans to continue living
                                            on this beautiful planet of ours.

                                            A SIMPLE MACHINE
                                              Like most mechanical devices, the
                                            moment they are built,  the  manufac-
                                            turer starts to analyze them, making
                                            “improvements” to the next units that
                                            are produced, i.e.,  the serial number
                                            emerges. When a customer purchases
                                            a crane and starts using  it, they pro-
                                            vide feedback as to what would make it
                                            better on the job site to speed things up
                                            and reduce the cost of labor. They talk,
                                            and the manufacturer responds. Tower
                                            cranes are of a relatively simple design,
                                            and have developed quickly to meet the
                                            changing needs for the taller building!
                                            Thus,  cranes  are continuously  modi-
                                                             continued on page 20
                                            All photos courtesy of Dennis O’Rourke unless
         Fig. 1: Model of crane run on horsepower.  otherwise noted.
         18     Wire Rope News & Sling Technology   June 2019
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