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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

Accelerated Bridge Construction (ABC) Decision Tool

A challenge transportation asset managers face is the need to cost effectively prioritize the repair and replacement of the large inventory of deteriorating bridges while considering the increasing budgetary constraints. Indirect costs such as traffic delay associated with the closure times during construction makes the decision making process more difficult. The bridge network is a vital link to the state transportation network and to economic development. The large investments in bridge repair and replacement, and the impact of their closures to the socio-economic vitality allow for opportunities to explore new construction techniques, planning approaches, and policies for their management (Alipour et al. 2018). Accelerated bridge construction (ABC) is defined by the FHWA as bridge construction that uses innovative planning, design, materials, and construction methods in a safe and cost-effective manner to reduce the onsite construction time that occurs when building new bridges or replacing and rehabilitating existing bridges (Culmo 2011). ABC uses both new technology and innovative project management techniques to mitigate the effects of bridge construction on the public, reduce construction costs, promote traffic and worker safety, and improve the bridge durability due to standardized and controlled construction conditions (Saeedi et al. 2013). In addition, oftentimes long detours, costly use of temporary structures, remote site locations, and limited construction periods present opportunities for use of ABC methods to provide more practical and economical solutions to those using conventional construction methods (Culmo 2011). Nine transportation agencies have seen ABC techniques reduce bridge construction time and save over $30 million (FHWA 2006). Additionally, ABC techniques on different bridge elements have improved the durability of bridge structures (Phares and Cronin 2015, Hosteng et al. 2016). ABC offers transportation agencies benefits, however, many agencies are hesitant to implement ABC due to perceived risks and higher initial costs (Kang et al. 2016). Another factor contributing to less adoption of ABC is the unavailability of decision making processes that would help agencies with the selection of candidate bridges and appropriate ABC techniques (Alipour et al. 2018). At the national level, there are multiple tools available to aid with ABC decision support. Among these methods, the most widely used approach is the ABC-AHP decision tool developed by the FHWA (2012). This method is based on analytic hierarchy process (AHP) that uses pairwise comparisons to evaluate the importance of defined factors relative to other factors using a numerical scale. The ABC-AHP decision tool consists of three components; the overall goal of the decision, a hierarchy of criteria by which the alternatives will be evaluated, and the available alternatives (Doolen et al. 2011). The alternatives evaluated are ABC or conventional methods against two levels of main elements a bridge construction project could relate to, with the first level being direct costs, indirect costs, schedule constraints, site constraints, and customer service. The second level are elements that impact the first level. This decision tool is used for a specific bridge project. In addition to FHWA, various state department of transportation (DOT) agencies have decision processes to determine the suitability of ABC on bridges needing replaced, rehabilitated, or newly constructed. A preliminary review of documents reveal there are decision processes in place in states across the country ranging from Connecticut to Minnesota and Iowa, to Utah and Oregon. The FHWA ABC-AHP decision tool is developed from the decision tool that was originally implemented by Oregon DOT. Minnesota DOT uses a 3-stage decision process to prioritize ABC bridges, while Connecticut DOT utilizes a decision matrix with weighted factors of importance for comparison of ABC and conventional methods.