NCHRP 20-7
Proposed Research Needs Statement
AASHTO Subcommittee on Bridges and Structures
Chair, Gregg Fredrick, Wyoming Department of Transportation
June 2014
TITLE
Guidelines for Design and Construction of Temporary Bridges
BACKGROUND / NEEDS STATEMENT
Temporary bridges are often desired to maintain traffic during bridge reconstruction projects and
are also utilized on an emergency basis to accommodate structures that are taken out of service
by unforeseen circumstances such as nature or vehicular collisions. From a national perspective,
the design and construction criteria for temporary bridges is an inconsistent practice among
agencies. Some agencies have special provisions covering this work, while other agencies have
no such provisions. Design of temporary bridges in accordance with the current AASHTO
LRFD Bridge Design Specification or alternative specifications may result in potential
over/under design for the following areas:
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Satisfying the Fatigue Limit State, and specifying details with infinite fatigue life, or a
specified number of cycles;
Satisfying the Extreme Event Limit State for seismic, wind, stream, and vessel impacts,
where the bridge is not anticipated to be in service for a particular event recurrence interval;
Satisfying exterior beam, deck overhang, and parapet loading criteria;
Satisfying bridge width, striping, and end treatment criteria;
Long term creep or prestressing losses in concrete elements;
Design of foundations for contraction scour, local scour and long term scour, and required
hydraulic opening for a given design flood event;
Live Load requirements, including special and routinely permitted vehicle classes;
Inspection frequency and coding requirements subject to NBI compliance;
Load rating requirements;
Limited traffic for temporary bridges where certain vehicles are restricted from use
It is also desirable to provide definitions and requirements to address the anticipated service
durations for “temporary” and “interim” bridges - given that these durations may vary
considerably, and may require the need for different structural and safety performance. The need
to define requirements regarding single-use temporary bridges/components versus multiple
deployment temporary bridges/components also exists.
Obtaining a national perspective of the current design and construction requirements used by
agencies for the procurement of temporary bridges may lead to the development of a more
consistent and unified set of performance based criteria. To achieve this goal, focused analytical
studies of existing temporary bridge specifications along with comparisons to AASHTO LRFD
Bridge Design Specifications, 17th Edition Standard Specifications, and the AASHTO Guide
Design Specifications for Bridge Temporary Works will need to be performed.
RESEARCH OBJECTIVE
The objective of this research is to synthesize the design and construction criteria that are used to
procure temporary structures to develop an AASHTO based document for temporary bridge
structures. This guideline will provide more consistency in the reliability and performance of
temporary bridges, and offer agencies with economically feasible options that will eliminate the
concerns of under/over designed temporary structures.
WORK TASKS
Tasks anticipated in this project include the following:
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Solicit individual agencies or manufacturers and compile temporary bridge design and
construction specifications.
Investigate the applicability of various AASHTO bridge design specifications for temporary
bridges such as:
o AASHTO LRFD Bridge Design Specification
o AASHTO 17th Edition Standard Specifications for Bridge Design
o AASHTO Guide Design Specifications for Bridge Temporary Works
Develop design and construction requirements, identify materials and create definitions for
the classes of temporary bridges based on anticipated service duration.
Recommend future guidelines for the selection, design and construction of temporary
bridges.
URGENCY
Owners, Designers, Contractors and Suppliers will have the information they need to make better
informed decisions regarding the design, construction, and specifications for temporary bridges
that are economically feasible and perform as intended. Focused analytical studies are needed to
develop these required guidelines.
FUNDING REQUESTED AND TIME REQUIRED
It is estimated that this research will take 12 months to complete and will require $100,000.
CONTACT PERSON
Carmen Swanwick, P.E.
Chair, T-4 Technical Committee for Bridge Construction
Chief Structural Engineer
Utah Department of Transportation
4501 South 2700 West
P.O. Box 148470
Salt Lake City, Utah 84114-8470
Phone: 801-965-4981
E-mail: cswanwick@utah.gov