Title

Characteristics of Decommissioned Bridges: Findings from a National Survey and Analysis of the NBI Archive

Document Type

Presentation

Publication Date

2018

Department

Mechanical and Civil Engineering

Abstract

This paper presents initial results from NCHRP Project 20-07 Task 397, “Characteristics of Decommissioned Bridges”. Major findings from Phase I, which includes findings from a national survey and comprehensive analysis of the NBI data files for 1992 to 2016 duration, are reported. Based on the findings from the literature and a national survey, primary drivers of bridge decommissioning were identified. All state-owned NBI structures were tracked throughout NBI files to gather the most comprehensive data set of decommissioned structures in the United States. This study aims to provide input to bridge managers on major measures that historically drove bridge decommissioning, as well as current criteria considered for bridge replacements. Six major categories were identified to be more influential than other factors for bridge decommissioning, which are deficiency status, bridge posting, structural evaluation, deck geometry, vulnerabilities and fair condition. After the potential drivers were identified, a two-level hierarchy (as primary and secondary drivers), and a priority order was assigned to the potential drivers. Structural deficiency, functional obsolescence, poor substructure condition, fair structural evaluation, and fair deck geometry are top five drivers of bridge decommissioning and account for the drivers for 87% of the sample. 2.3% of the sample did not have any drivers associated with them. The findings show that, although deficiency has been the major performance measure over the years, it was not the single criterion the state DOTs addressed through bridge decommissioning. Fair evaluations of condition, geometry and vulnerabilities appear to have also been addressed by bridge replacements, more frequently compared to other potential factors.

Publication Title

97th Transportation Research Board Annual Meeting

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