OUINCY BAY BRIDCE 



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Figure 1 7. — Chicago, Burlington and Quincy Railroad bridge over Quincy 

 Bay (branch of the Mississippi River) at Quincy, Illinois. The pivot draw- 

 span was formed of two Bollman deck trusses supported at their cuter ends 

 by hog chains. The bridge was built in 1867-1868 by the Detroit Bridge 

 and Iron Co., Bollman licensee. (Clarke, Account of the Iron Railway Bridge 

 . . . at Quincy, Illinois.) 



and a certain amount of fabrication. There is some 

 likelihood that eventually fabrication was entirely 

 discontinued at Mount Clair, and all parts subse- 

 quently purchased from Bollman. 



The firm prospered, erecting a number of major 

 railroad bridges in Mexico, Cuba, and Chile. Opera- 

 tions ceased from 1861 to 1863 because of difficult 

 wartime conditions in the border city of Baltimore. 

 Following this, Bollman reentered business as sole 

 proprietor of the Patapsco Bridge and Iron Works. 



The most noteworthy of Bollman's works in this 

 period was a series of spans at Harpers Ferry. The 

 B. & O.'s timber bridge had been destroyed by Con- 

 federate forces in June 1861, and the crossing was 

 thereafter made upon temporary trestlework. This 

 was a constant source of trouble, with continuing 

 interruptions of the connection from high water. 

 washouts, and military actions. The annoyance 

 and expense of this became so great that the company 

 decided to risk an iron bridge at the crossing. In 

 July and August 1862, two sections of Bollman truss, 

 spans no. 4 and no. 5 were completed. As this oc- 

 curred during the time when W. Bollman and Com- 

 pany was inoperative, the work was produced at 

 Mount Clair to Bollman's design and, undoubtedly, 

 erected under his supervision. Five weeks later, on 

 September 24, these and Bollman's famous Win- 



I hi hi -pan 11! 1851 were blown up by the Confed- 

 erates, and the line's business was again placed at the 



I I hi 1 5 nt trestling. 



The spirit of the B. & O. administration indeed seems 

 to have been unshakable when, in the lace of such 

 heartbreaking setbacks, il determined to again bridge 

 the river with iron, even at the height of the hos- 



tilities. In November, span no. 5 was erected, and 

 by April 1863 nos. 3, 4, and 6 also. These were the 

 four straight spans in midriver between the "wide" 

 (or "branch," or "wye") span and the span on the 

 Maryland shore over the Chesapeake and Ohio Canal 

 (see fig. 13). Although the wood floor system of 

 these spans was burned for strategic reasons by U.S. 

 troops later in 1863, they survived the war. 



In 1868 the remaining trestlework was replaced 

 with Bollman trusses. This magnificent structure 

 served the railroad until 1894 when the right-of-way 

 was realigned at Harpers Ferry. However, the half 

 used by the common road remained in use until 

 carried away by the disastrous flood in 1936. The 

 piers may still be seen. 



During the prewar years, Bollman evolved a struc- 

 tural development of most profound importance, 

 which is usually associated with the Phoenix Iron 

 Works and its founder, Samuel J. Reeves. In the 

 erection of a high trestlework viaduct for the Havana 

 Railroad. Bollman apparently became concerned 

 with the tensile weakness of cast iron when applied in 

 long, unsupported columns. Although a column 

 is normally subjected to compressive stresses, when 

 the slenderness ratio — that is, the length divided by 

 the radius of gyration of the cross section — becomes 

 great, a secondary bending stress may be produced. 

 If this stress becomes great enough, the value of the 

 tensile stress in one side of the column may actually 

 exceed the principal compressive stress, and a net 

 effect of tension result. 



As already mentioned, the few available rolled-iron 

 shapes were of relatively small area and quite unsuit- 

 able for use as columns unless combined and built up 



92 



I'l I I 1 I IN 240: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



