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Context-sensitive Solutions in Bridge Design
By Robert Breen, PE
Cove Point bridge’s stone finish was created with textured concrete and stains to blend with the natural setting of Lake Erie Metropark.
The award-winning Friendship TrailBridge over Tampa Bay was rehabilitated in response to citizen support to preserve this structure.
The facade of Lovers Lane Bridge over I-94 was enhanced by using simulated Stone Masonry and other elements to match a nearby community school building.
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Context-sensitive solutions or CSS is an approach that has come to the forefront in transportation projects to
develop facilities that fit their physical setting and preserve scenic, aesthetic, historic and environmental
resources. CSS is a holistic approach to enhancing transportation projects.
Bridge projects often require a context-sensitive approach to satisfy stakeholder needs and their safety, and
to preserve the values of the area. CSS comes into play early in the planning and design process when a new
bridge is required, or when an existing bridge is slated for replacement or rehabilitation. Rehabilitation may
be preferred if there is a strong sense of adjacent aesthetics or history associated with the bridge. If
replacement is the best alternative, the many design elements that combine to provide a complete bridge need to
be considered.
Bridge design encompasses more than just the bridge structure. Its location in a rural, urban or suburban area
can impact how its physical elements should blend with the surrounding landscape or building features. The Michigan
Department of Transportation’s (MDOT) reconstruction and widening of Lovers Lane Bridge over I-94 in the Kalamazoo,
Michigan, area exemplifies this aspect. Local and state stakeholders agreed that matching the bridge’s facade to
an adjacent high school in the City of Portage would provide a complementary look. Simulated stone masonry was
incorporated on the abutment and return walls. Textured concrete, a colored surface coating, aesthetic railings,
and pilasters at the bridge’s four corners further enhance the area.
The owner’s requirements for a desired look also impact bridge design as was the case in Macomb County,
Michigan. The County wanted treatments to mimic an agricultural theme for a pedestrian bridge over M-53. Steel
pedestrian railing is being used to look like a wooden farm fence while maintaining safety for users. A portion
of the bridge is proposed to be covered with a barn-like roof structure, and a fieldstone finish will be used on
the approach walls and center pier. Form liners can be used to achieve the rural look of fieldstone or brick on the
exterior concrete without compromising structural integrity. These finishes allow a rich contrast that plain
concrete does not provide.
Public involvement also influences bridge projects. Residents are concerned about the environment and a project’s
impact on their community. Roads and bridges are vital systems of the environment -- how they function, what they
look like, and their potential impacts on nature are important to stakeholders. When the Florida Department of
Transportation (FDOT) built a new bridge connecting Hillsborough and Pinellas Counties, they planned to demolish
the outdated bridge. Overwhelming citizen response led the Counties to assume ownership of the bridge and rehabilitate
it into the recreational Friendship TrailBridge that has been recognized for its historic preservation.
Each project has a unique set of functional challenges that may need to be addressed as part of CSS. Special considerations
were taken on the Ohio Department of Transportation’s POR-303-5.75 Bridge to preserve the Cuyahoga River, which is
designated as a Scenic River. The design specified construction methods to decrease the likelihood of disturbing
endangered species discovered living on the submerged piers and along the embankment. Typical epoxy coating details
were only used on the pier caps and not on the submerged piers so the environmental habitat would be maintained.
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Aesthetics are vital to a successful bridge project and its positive effect for users. Using concrete arched crossings in
lieu of straight beams provides a softer look. Manufacturers now design precast, arched systems that span 50 to 100 feet,
significantly longer than previous 20- to 35-foot systems. Textured concrete, used in the replacement of the Huron-Clinton
Metropolitan Authority’s Cove Point Bridge in Lake Erie Metropark, presents a more pleasing look than plain concrete. The
new structure now blends into its natural, Michigan setting. Adding new treatments to railing fascias, like vertical fissured
or recessed panels, is also a simple way to enhance a bridge’s appearance and maintain costs.
Recycling of bridges for recreational purposes is a growing trend. Many “Rails to Trails” projects were former rail corridors
with bridges built 50 to 100 years ago to carry freight trains across streams, rivers and other natural features. Macomb
County, Michigan, is converting seven former railroad bridges within an 18-mile corridor for the Macomb Orchard Trail
project. These timber structures are being recycled with relatively inexpensive retrofits and upgrades to make them
structurally-sound and ADA-compliant, while retaining their historic flavor. In Clearwater, Florida, the foundation of a
four-span bridge section is being saved for a new recreational bridge, while the remainder of the existing bridge will be removed.
The preserved section is proposed to be reconstructed as a pedestrian and fishing area. An adjacent gangway ramp will be
added leading to a floating boat dock that also incorporates existing foundation piling.
As with most changes, there are concerns with context-sensitive solutions – the biggest is increased cost. The cost-benefit of
these solutions to the overall project must be thoroughly evaluated because the benefits of CSS are not always tangible.
Some solutions can be assessed in monetary value, and adjustments can be engineered into the project to minimize costs.
Form liner finishes initially add $5 to $7 per square foot, while reusing form liners multiple times on a project can
reduce these added costs to less than $1 per square foot.
Sharing of CSS costs can minimize their impacts on stakeholders. For the Friendship TrailBridge, FDOT pledged the money
set aside for the originally-scheduled bridge demolition to Pinellas and Hillsborough Counties for use in the rehabilitation.
This partnering process facilitated completion of the historic preservation. Funding for the widening of the Lovers Lane
Bridge and the incorporated aesthetic finishes was shared by MDOT and the City of Portage.
Context-sensitive solutions create bridges and structures that complement nature and our society. By involving those impacted
by a project, the values of the users and the community are reflected in the solutions. These bridges preserve the
environmental, historical and architectural values of the area and will endure well into the 22nd century.
Robert Breen, PE, is a Project Manager with more than 30 years of structural engineering experience working on local agency
and interstate bridge projects. He specializes in bridge design, inspections, scoping, and construction assistance. He can
be reached at 734.947.9700 or rbreen@wadetrim.com.
Originally published in Innerview Vol. 20, No. 3, 2006
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