Is the 1-74 bridge constructible and will it be safe?

The size and complexity of the long span steel arches dictate that construction engineering becomes an important factor in the fabrication and erection of the arches. The difference between the design engineering (safety) and the construction engineering (constructability) needs to be understood.

Design Engineering is a process well known to structural engineers. It involves the application of design principles to prepare a safe design. Using this design, engineers prepare plans and specifications that define the bridge the owner wants in place when the project is completed.

Construction engineering requires extensive practical experience. It involves guiding the fabrication and erection operations needed to place the arch segments. Each piece must be lifted up in the air and placed in accordance with the geometry and stress requirements specified in the designer's contractual documents.

I have been fortunate to design many bridges and worked with design-construction teams to eliminate constructability problems from construction documents. For the past 35 years, I have worked with contractors to solve their constructability problems. In every case, improving constructability improved the design and efficiency of construction operations.

Successful projects require a team of three members: the owner, the engineer and the contractor. All three members on the 1-74 Bridge are experienced, reputable, and have a long history of successful bridge design and construction.

Their teamwork will result in a safe bridge.

William D. Ashton

Licensed structural engineer



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