File:88b102 Betty June Walker upbound in Portland Canal at Conrail Bridge lift span (15529761814).jpg

. Towboat "Betty June Walker" (doc. # 248942) upbound in Portland Canal , passing under lift span of Conrail (later L&I) Bridge. [Another name for this bridge which remains constant despite changes in ownership is the Fourteenth Street Bridge.] . The lift span was built in 1918, replacing an earlier swing span at this location. This was about the time that the canal was widened from 90 to 200 feet, the 600-foot lock was built and the pool above the dam was raised eight feet to 420 feet above sea level. The span is 260 feet long (horizontal clearance for boats is 242 feet) and weighs about 2.6 million pounds. In the lowered position, vertical clearance above the river (at pool stage) is 39 feet; when raised, the clearance is 70 feet. The weight of the span is supported by a total of 64 two and one-eighth inch steel cables which pass over sheaves at the tops of the towers and connect to two huge counterweights. Because the weight of the span is balanced by the counterweights, it can be raised and lowered by a relatively small electric motor inside an enclosure on top of the span. The towers and machinery of the lift span were designed by [J.A.L.] Waddell and Son, Inc., and there is a plaque on the span reading, "Waddell Vertical Lift Bridge, Waddell and Son, 1917".

See "Engineering News-Record", Vol. 82, No. 21, pp. 1007-1011 (May 22, 1919) and "Dr. J. A. L. Waddell's Contributions to Vertical Lift Bridge Design" (a 2002 paper in PDF format) from Heavy Movable Structures, a not-for-profit technical organization. . Guidewall at lower right looks fairly new, but I don't know when it was constructed.

Ohio River mile 605. Louisville, Kentucky. February 1988. file # 88b102. . 35 mm Kodachrome. Plustek OpticFilm 7600i and Silverfast 8. Picture Window 6.