F-4: Concrete Bridge Design

 Statement of the Case: Engineer A, who recently moved to British Columbia from Ontario,

learned from a classmate at a reunion that a mining company needed a design for a bridge over a

creek, near a mine in the mountains. Engineer A had designed a single-lane timber logging

bridge over a creek in northwestern Ontario but had no other bridge experience. He approached

the mining company, stated that he had extensive experience in bridge engineering, and

eventually received the contract for the design. The site was at the base of a steep slope, and the creek was full of rocky debris. No flow records were available for the creek, so Engineer A

determined the span and clearance based on the creek’s high-water marks. He felt that the site

was adequate and did not arrange for geotechnical investigation or advice. He designed a

standard concrete box-girder bridge with a 15 m span and pile-driven abutments. A building

contract was also hired. The contractor was familiar with mine construction and mechanical

plants, but had no experience in bridges. Nevertheless, the construction went smoothly. The

bridge served well for five years, but a debris torrent during a particularly rainy winter season

destroyed the bridge in the sixth year.

Question: Did Engineer A act ethically in this project?

Outcome: The mining company regretted the loss of an expensive bridge, particularly because

the loss interrupted mine operations for months. The company hired an experienced bridge

engineer as a consultant to investigate the reasons for the bridge failure. The consultant noted the

debris in the creek and concluded that it was likely deposited by torrents. This design constraint

should have been satisfied by relocating the bridge site, providing a debris basin, increasing the

vertical clearance, and/or by altering the design in other ways. The mining company complained

to the Association, seeking disciplinary action against Engineer A.

Authors’ Comments: Engineer A clearly misrepresented his qualifications to his client. He had,

in fact, minimal bridge experience, and none of that was in the mountains. In this way, he was

not acting in good faith with the client, as required by the Code of Ethics. 

A more serious error, however, is that he did not have adequate knowledge of the type of structure he undertook to design (a key principle in almost every Code of Ethics), and he failed to seek help and guidance to protect the interests of the client. 

An engineer or geoscientist need not be an expert in every phase of a proposed project before accepting it, but must become competent through study or

research, in a reasonable time. 

Alternatively, a consultant can provide advice. The client’s project must not be put at risk because of the engineer’s lack of knowledge. In this case, Engineer A should simply have engaged a consultant to provide geotechnical advice.