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Beginning his career as an engineer with the Iowa Highway Commission in 1922.: James "Jimmy" Whitmore Johnson

James "Jimmy" Whitmore Johnson
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Other Engineering
Company/ Affiliation:
Iowa Highway Commission

James “Jimmy” Whitmore Johnson began his career as an engineer for the Iowa Highway Commission as an inspector 1922. In 1924 he became assistant engineer for the engineering experiment station. In 1927 Jimmy was named assistant lab chief at the Iowa Highway Commission and lab chief in 1938.

In 1946 Jimmy and two other commission employees, Rudy Schroeder and Willis Elbert attended a demonstration of cement-treated base construction. After witnessing this Jimmy believed a concrete mix with an increased proportion of cement then vibrated into place by machine would eliminate the need for fixed forms and increase the amount of road pavement that could be laid in a day.

In 1947 at the Ames laboratory Jimmy and the others constructed a prototype that extruded a slab of portland cement concrete 18 inches wide by 3 inches deep. In 1948 the second larger model was built and tested. With this model, a 3-foot wide, 5 inch thick section of sidewalk was slipformed.

A public project in Sept 1949 for the Highway Commission on a bid to pave a 20-foot wide, half-mile section of highway through Primghar in northwest Iowa was rejected due to cost. As a result the Commission, O'Brien County Board of Supervisors, and Primghar officials decided to experiment with the new slipform paver designed by Jimmy.  Grading began on Sept. 19, followed by paving on Sept. 28 and was finished on October 1, 1949.

The slipform paver is held as one of Iowa's greatest contribution to highway construction, significantly impacting the economics and nature of portland cement concrete road construction. The slipform paving machine was also instrumental in accelerating the construction of the greatest road building project in American History-the interstate highways system.

Jimmy, was referred to as the "father of the slipform paver," and he retired from the Iowa Highway Commission in 1966. In New York City on 1968, he was presented the American Concrete Pavement Association's first Hartmann Award (now known as the Hartmann -Hirschman Award).

On 1979, he received the Iowa Concrete Paving Associations' Outstanding Achievement Award for his contributions to the industry during his career at the Iowa Highway Commission.

Johnson was born in 1899, on a farm near Thurman in Fremont County, the youngest of six brothers. Following service in World War I, he enrolled at Iowa State College, graduating with a B.S. in civil engineering. In 1927 he received his master's degree. 

With great honor we recognize James Whitmore Johnson “Jimmy” as a Hero of Industry and Technology for his contribution to transportation with invention of the slipform paver. Accepting in honor of Jimmy and on behalf of the Iowa Department of Transportation is John Adam, Highway Division Director. 

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