570 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1937 



of 4,500 pounds per square inch squeezed it into a circular cross-section 

 SGY?. inches in diameter. Under tliis pressure narrow steel bands were 

 applied about 3 feet apart to bind the cable together until the wrappmg 

 could be appHed. Finally, the cable is closely wrapped with steel wire 

 which holds it compact, and protects it against both mechanical injury 

 and the weather. 



During the year required for construction of the cables, the steel 

 work for the suspended structure or bridge floor was fabricated and 

 delivered. This steel work was erected by means of traveling derricks, 

 two of which started from each tower, one worldng toward the shore 

 and the other toward midspan. These travelers simply attached the 

 steel to tlie suspenders which hang from the cables at 50 feet intervals. 

 They thus proceeded, laj4ng their own track ahead of themselves. 

 The two main span travelers met at midspan and then each started 

 back toward the towers setting the handrailing, curbs, and the re- 

 mainder of the floor members, leaving behind them a completed steel 

 structure ready to receive the paving. Meantime, the other two trav- 

 elers from the shore ends also worked back to the towers, completing 

 erection of the side spans. Addition of the concrete pavement to the 

 structure completed it, ready for traffic. 



The engineers on the Golden Gate Bridge were especially concerned 

 about the safety of the workmen on the job. According to all precedent 

 it was feared that anywliere from 6 to 12 men woidd be killed in the 

 erection of the structiu-e. The very thought that the execution of 

 work called for by your plans may involve such a toll of Hves gives you 

 a mighty imcomfortable feeling. Any conceivable safeguard which 

 would reduce the hazard must be earnestly considered. Many simple, 

 helpful measures were taken, and the result of these ordinary pre- 

 cautions is reflected in the low accident record. After a careful study, 

 the engineers decided ui)on a safety measure that had never been 

 applied on any other job. They concluded that as the suspended 

 structure was built out from the towers, huge nets should be stretched 

 across beneath and suspended from tliis steel work. It would be 

 possible so to devise this that even the workmen at the extreme 

 forward part of the work would be protected by a net carried on a 

 framework cantilevered out ahead of the traveler. The net would 

 extend for the full width of the bridge and 10 feet beyond on each side. 

 Upon completion of the floor erection there would be suspended from 

 it a continuous net 110 feet wide and 6,500 feet long, which, like a 

 safety net in a circus, would catch men who lost their footing and save 

 them from a drop of 250 feet into the sea and certain death. The cost 

 of this net, its erection, and subsequent removal would be about 

 $130,000. The engineers said this was not too much to pay for the 

 lives of the men who woidd be saved. They asked the Bridge District 

 to contribute $82,000 and the contractor the balance. The District 



