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The National Academies

NCHRP 25-25/Task 118 [Anticipated]

Context-Sensitive Design Options for Workhorse Bridges in Rural Historic Districts
[ NCHRP 25-25 (Research for the AASHTO Committee on Environment and Sustainability) ]

  Project Data
Funds: $110,000
Staff Responsibility: Ann M. Hartell
Comments: In development
Fiscal Year: 2018

A workhorse bridge is defined as a bridge less than 300 feet in length (1 or two spans), generally from constant girder-type structures assembled from standard structural components and systems.  When replacing a bridge in a rural historic district that is contributing to that district, mitigation usually involves replacing the bridge with a “context-sensitive” new bridge.  However, even when the bridge is not contributing to the historic district, there are potential adverse effects to the historic district if the new bridge is not context-sensitive, i.e. does not follow Secretary of Interior Standards.  Although the context is established – a rural historic district – and the context-sensitive approach would strongly suggest matching the bridge aesthetics with the rural character of the historic district, there is very little guidance on what appropriate responses to that context might be.  Although bridge replacement projects in rural historic districts are a common project type a DOT undertakes, national guidance, such as the Bridge Aesthetics Sourcebook, suggests a finite suite of aesthetic responses for this setting and a potential benefit to targeting guidance to this particular setting.

Increasingly, SHPO's and NPS are taking a landscape perspective on historic resources, leading to more and larger rural historic landscapes/districts. Within these districts are bridges that need replacement but are contributing to the historic district. The logical solution is to propose a context-sensitive design replacement; however, neither the SHPO nor often the DOT knows just what that means. Having a tool kit of successful ideas makes the consultation over resolution of adverse effects more predictable and allows all partners to better visualize the outcomes.

The objective of this project is to review bridge aesthetic guidance from state DOTs, culling from them guidance that would be relevant to workhorse bridges in rural historic districts. The project should collect and compile information on how the specific solutions were integrated into the overall design process rather than applied as an ad hoc, add-on aesthetic treatment. Information on constructability, cost, and maintenance with regard to the most commonly suggested CSD options, i.e., barrier designs, railings, color, and form liner, should be included. The anticipated research products include a focused and concise tool kit of CSD solutions that are not only that they are aesthetically pleasing, appropriate to their context, and meet the transportation need, but are replicable at reasonable costs and can be maintained.

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