Inventory database was used, and the models have the NBI condition ratings as their response variables. The model families were categorized by administrative region, functional class, and superstructure material type. The explanatory variables include traffi c volume and truck traffi c, climatic condition, and design type and features.
FindingsThis study used the NBI database to develop families of deterioration curves for the bridge deck, superstructure, and substructure components. The study confi rmed that environmental variables play a signifi cant role in bridge deterioration. For several of the deterioration models, the climate variables of freeze index, number of freezethaw cycles, and average precipitation were found to be signifi cant predictors of bridge component deterioration.Compared to the superstructure and substructure, deck deterioration was found to be more aff ected by traffi c loading. It was also observed that bridge components that had undergone some repair since their construction exhibited patterns of deterioration that were diff erent when compared to those that had not received any such JOINT TRANSPORTATION RESEARCH PROGRAM
The concept of project bundling—combining multiple projects into a single contract—continues to gain momentum. Unanswered questions from past studies include how to quantify project bundling benefits. This paper addresses the issue using a data-driven approach that involves initial comparisons of the unit average project costs of single and bundled projects, preliminary investigations of the potential influential variables of project cost, the development of project cost statistical models, and an analysis of past and possible future bundling strategies. The study found that the primary drivers of project cost include the project size (economies of scale), bundling strategy (economies of bundling), and bidding market conditions (economies of competition). It is also shown that the similarity between different project types in terms of their constituent pay items is an influential factor on project cost. The study confirmed that larger contracts yield economies of scale but may also lead to less competition (discouraging all but the largest firms from bidding). This finding suggests the existence of a contract-size threshold beyond which the unit project cost increases with increasing project cost. By analyzing past bundling strategies, the study identified the most frequent combinations of work categories in the past bundled contracts. The study also carried out scenario analyses using hypothetical bundling strategies applied to actual past projects and determined that bundling projects using a carefully designed strategy can yield significantly reduced overall contract costs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.