Economic Impact of Multi-Span, Prestressed Concrete Girder Bridges Designed as Simple Span versus Continuous Span

Project Details
STATUS

Completed

START DATE

07/01/14

END DATE

09/30/16

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC, CTRE, MTC
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board
Midwest Transportation Center
USDOT/OST-R

Researchers
Principal Investigator
Travis Hosteng

Co-Director, NCWTS

Co-Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

About the research

The objective of this study was to determine the economic impact of designing pre-tensioned prestressed concrete beam (PPCB) bridges utilizing the continuity developed in the bridge deck as opposed to the current Iowa Department of Transportation (DOT) method of utilizing standardized spans treated as simply supported. This work consisted of a literature search and review, survey of other highway agencies, design comparisons, and cost-benefit analysis.

The design review consisted of comparisons of the standard design practices in terms of material use and cost from a review of electronically published design manuals, standards, and practices for state DOTs. Furthermore, the design review examined design cost, as determined by design hours spent to produce final bridge plans using the different design methodologies from state DOT survey respondents.

The cost-benefit analysis was based on construction costs from the Federal Highway Administration (FHWA) National Bridge Inventory (NBI) (with corrections to account for the different years the costs were recorded and the different regional bridge locations) and material and design costs from the design review.

Based on the evidence included in the final report for this project, the researchers concluded that simple span designs have a lower initial cost compared to continuous designs, in terms of construction cost and design time.

The lower construction cost demonstrated by the simple span designs in contradiction to theoretical material efficiencies in continuous design is an indicator that many of the continuous designs utilized are not optimized to the extent possible. While significant recent research has been completed on optimization methods for prestressed concrete bridge design, the majority of them remain undeveloped for practical application.

Due to the lack of strong evidence in favor of either design method in terms of long-term cost and performance, the research team concluded that simple span designs are preferable at this time.


Funding Sources:
Iowa Department of Transportation
Iowa Highway Research Board ($75,395.00)
Midwest Transportation Center
USDOT/OST-R ($75,302.00)
Total: $150,697.00

Contract Number: DTRT13-G-UTC37

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