Urban Bridge Design Considerations | Part II by: Steve Kathol, P.E., S.E.

Designing bridges in urban areas can present multiple challenges that are not as common in more rural settings. Urban bridges are often constructed in locations with limited setback to other properties or buildings; are often required to carry a high volume of arterial or collector street traffic; are often critical to maintaining access to a business, residential development or other facility that is significant to the community; and often involve some level of aesthetic enhancement to better align with a city’s urban development plan. In the eyes of the public, successfully addressing each of these considerations may be the difference between the success or failure of a project.

Part 1 of this series focused on the topics of noise and vibration. There are three additional important aspects of urban bridge design. These, among many others, are part of Schemmer’s normal design practice for urban bridge projects.

  • Traffic Phasing and Detour Routes – Each Schemmer project is unique when working with traffic phasing and/or detour routes. Constructing a bridge in multiple phases could add 15-35 percent in construction costs. Phased construction can also nearly double the time that is required to construct a bridge. However, maintaining traffic on a bridge may take precedence over these cost and time issues. This can be a very controversial subject within a community and requires skillful engagement of the public to reach acceptance.

Schemmer designed the Harris Overpass project in downtown Lincoln, Nebraska in 2008. Close to 20,000 vehicles per day were detoured for 11 months during the project timeframe. Nearby business owners and the traveling public preferred this option over a two-year construction schedule that would only maintain a single lane of traffic in each direction.

  • Public Involvement – Involving the public early in the design and planning stages of an urban bridge project can be critical to limiting controversy and achieving public buy-in. Consider a citizen advisory panel to provide input on controversial issues and to use as a sounding board for project details.

A 10-person citizen advisory panel was assembled for the Harris Overpass project. This panel was educated by the design team on issues relating to traffic phasing, structural design options and aesthetics. After design decisions were made, the members of this panel were able to accurately explain to their constituents why certain decisions were made. This proved invaluable during public hearings. The citizen advisory panel helped to create mutual understanding by explaining to their neighbors and fellow business owners the reasons why certain project details were required.

  • Aesthetic EnhancementsUrban design enhancements can be very important to a community and bridges provide a great canvas for such features. These enhancements can range from simple form liners or concrete staining, to signature structures of arch or cable-stay construction.

On the Harris Overpass project, stone inlay and ornamental lighting were used above roadway deck piers to blend the bridge’s look with the surrounding historic Haymarket District. Additionally, public artwork was installed on the U.S. 6 Broadway Viaduct to add aesthetic appeal, in accordance with the community’s master plan.

At Schemmer, we pride ourselves on our highly responsive service and mutually satisfying client relationships. From rural and urban roadway design, to transportation structures and traffic engineering, our goal is to enable our clients to define and achieve their goals.

For more information on Schemmer’s transportation group, click here.