Including User Cost and Risk Analysis during Construction in Highway Bridge Structure Selection

摘要

Bridge type selection traditionally has been conducted in terms of the finished structure. Thisstudy presents a more comprehensive analysis that includes user costs and accidents during theconstruction phase. This approach can lead to a total cost optimization for more effective andefficient bridge project designs for the public.From a total of 163 Colorado bridges constructed during the period 2000-2007, bridge, roadway,traffic and region data were used to select a total of 43 candidate bridges targeted for study. Ofthese, complete data were compiled on 20 bridges. User costs were computed based on a delaycost formula, and actual accident data were obtained.Graphs compare the delay costs and bridge costs for each structure, and also the trends by region,ADT, construction duration and bridge type. Accident rates were compared during constructionwith those before and after. Statistical factor analysis was used to isolate key factors among thebridges studied.Delay costs exceeded bridge construction cost for approximately half of the bridges studied,particularly in regions with higher ADT. Accident rates were essentially unchanged duringconstruction for property damage only accidents and fatality accidents, but there was an almost20% increase in the number of injury accidents.Structure type and construction duration are important decision variables with respect to usercosts, and these two are related. Delay costs are significant as a ratio to bridge costs when ADTexceeds 10,000, construction when duration exceeds 20 months, and for concrete box girderprestressed bridges that are built with current Colorado construction practices.