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ABC-UTC Guideline for Development of Guidelines to Establish Effective and Efficient Timelines and Incentives for ABC
Reduction of road closure times, traffic disruption and user costs, in addition to improvements in construction quality and utilizing prefabricated elements, are all attractive qualities of the implementation of ABC techniques that encourage the transportation agencies to use the technique for repair and replacement projects. ABC helps minimize onsite construction activities, results in decreasing the long-term presence of contractor related equipment, labor, and staging areas and consequently can decrease driver distractions and traffic disruptions that reduce the safety and mobility efficiencies of the transportation network.
The total cost of bridge replacement includes the direct costs which are commonly identified as the design, materials, and construction cost and indirect costs that are costs associated with the lower quality of network performance (due to traffic delays or longer reroutes) and opportunity losses that represent the socio-economic (and event environmental) losses due to the closure. The total cost of construction of the bridge is the addition of these two. One should note that some traffic safety issues also lead to inevitable costs, such as accidents occurring because of partial lane closures and drivers unfamiliar to the detour route.
This underlines the importance of implementing effective strategies to repair/replace the bridges in the shortest possible time. Oftentimes long detours present opportunities where the use of ABC methods can provide more practical and economical solutions to those available with conventional construction methods.
Two time metrics are used when determining the amount of impact to the road user: i) Onsite construction time, which is the period of time when a contractor alters the project site location until all construction related activities are removed. This includes, but is not limited to, the removal of maintenance of traffic items, construction materials, equipment, and personnel; and ii) mobility impact time which is any period of time the traffic flow of the transportation network is reduced due to onsite construction activities (FHWA).
The mobility impact time is classified to five tiers: 1) traffic impacts within 1 to 24 hours; 2) traffic impacts within 3 days; 3) traffic impacts within 2 weeks;, 4) traffic impacts within 3 months; and 5) overall project schedule is significantly reduced by months to years. Each tier dictates the type of technology the owner will use. For example, a Tier 1 project would use a slide-in construction method, whereas a Tier 3 project would require on-site assembly of prefabricated bridge elements and systems.
The main objective of the proposed project is two folds: 1) Provide guidelines to evaluate the direct and indirect costs (traffic delays and opportunity losses) under following conditions: conventional construction, only ABC techniques, only incentivizing strategies, and combination of ABC and incentivizing strategies; and 2) Develop a decision-making framework to compare the total costs and durations of each of the candidate techniques to optimize for the lowest cost and construction duration techniques accordingly. Here, ABC techniques refer to foundation and wall elements, rapid embankment construction, prefabricated element and systems, self-propelled modular transporters (SPMTs), slide-in construction, longitudinal launching, horizontal sliding or skidding, and fast tracked contracting.
The proposed research will develop a holistic decision making framework to optimize the project duration and total costs and provide guidance on use of incentives. The following tasks will be executed to achieve the project objectives.
The following tasks will be performed to achieve the project goals:
- Task 1 – Literature Review: Review of the literature on i) available ABC techniques, ii) cost and duration of the ABC projects, iii) data and experiences of DBE projects, and iv) best practices for indirect cost analysis.
- Task 2 – Identify different construction techniques and contracting mechanisms: Cost and closure time associated with a series of different construction and contracting techniques will be estimated.
- Task 3 – Investigate the bridge closure status to estimate the indirect costs: The possibility of using more holistic metrics such as social return on investment (SROI) to estimate the indirect costs will be examined.
- Task 4 – Optimize the total cost and select the best ABC technique: To find the most optimized approach a linear mathematical optimization model will be developed, which minimizes project total cost and takes into account the project duration.
- Task 5 – Final report: A final report discussing the procedure, outcomes, and any possible guidelines will be prepared.
Principal Investigators: Dr. Alice Alipour and Dr. Jennifer Shane
Research Assistant: Ning Zhang
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