John Alexander Low Waddell (1854- March 3, 1938, often shortened to J.A.L. Waddell and sometimes known as John Alexander Waddell) was an American civil engineer and prolific bridge designer, with more than a thousand structures to his credit in the United States, Canada, as well as Mexico, Russia, China, Japan, and New Zealand. Waddell’s work set standards for elevated railroad systems and helped develop materials suitable for large span bridges. His most important contribution was the development of the steam-poweredhigh-lift bridge. His design was first used in 1893 for Chicago's South Halsted Street Lift-Bridge over the Chicago River; he went on to design more than 100 other movable bridges, and the company he founded continues to make movable bridges of various types. Waddell was a widely respected writer on bridge design, and an advocate of quality training of engineers. Many of Waddell's surviving bridges are now considered historic landmarks.
One of his most notable works is the ASB Bridge in Kansas City Missouri.It is only one of two of this design ever built, and is in use as a railroad bridge for the BNSF.