Subsequently, the Portland Cement Association (PCA) hired Janney to conduct research on prestressed concrete at its newly constructed laboratories in Skokie, Illinois, where he worked from 1950 to 1956.

Janney's first project as a consulting engineer was on behalf of the Illinois State Toll Highway Authority, overseeing the manufacturing of precast, prestressed concrete girders for bridges for the tollway.

Janney performed more than 60 scale-model studies from 1958 to 1969 on many important structures, including Chicago's First National Bank, the Kodak Pavilion at the 1964 New York World's Fair, and the hyperbolic paraboloid roof for TWA's maintenance hangar in Kansas City, Missouri.

WJE needed to design, construct, and test a scale model of the roof for the TWA Maintenance Hangar due to its unusual geometry.

A member of numerous professional organizations, Janney served many years on the Research Council on the Performance of Structures for the American Society of Civil Engineers (ASCE).

Engineering News-Record (ENR) twice honored Janney with its "Those Who Made Marks" designation in 1967, for his full-scale testing (to failure) of several buildings at the New York World's Fair and in 1982 for innovations employed in the rehabilitation of Chicago's Soldier Field.