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Prefabricated Bridge Elements & Systems (PBES), Decision-Making Framework

Claude Napier Sr. Structural Engineer Resource Center - Structures TST. Prefabricated Bridge Elements & Systems (PBES), Decision-Making Framework. Learning Outcomes. Understand the ABC viable concepts Understanding of barriers/obstacles to install PBES in hours or days

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Prefabricated Bridge Elements & Systems (PBES), Decision-Making Framework

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  1. Claude Napier Sr. Structural Engineer Resource Center - Structures TST Prefabricated Bridge Elements & Systems (PBES), Decision-Making Framework

  2. Learning Outcomes • Understand the ABC viable concepts • Understanding of barriers/obstacles to install PBES in hours or days • Understanding of needs/opportunities to install PBES in hours or days • Knowledge of PBES decision-making framework

  3. Learning Outcomes • Be able to use flowchart and/or matrix questions for decision making to identify important considerations to determine best course of action for bridge construction • List and define rapid onsite construction factors • List and define other factors impacting the decision to use ABC or prefabricated structures

  4. Learning Outcomes • List and define the different costs factors influencing the PBES decision • Be a champion to promote PBES Technology

  5. ABC Viable Concepts • Ground up • Material Choices • Equipment • Prefabrication • Access-logistics • Pre-assembly • Pre-purchase & fabricate • Off site Assembly • Off site roll-in or lift-in

  6. ABC Viable Concepts • Incremental launching • Longitudinal versus transverse components • Contracting techniques to be considered: • performance related specifications • warranties • design/build • cost + time • lane rental • incentive/disincentives • value engineering

  7. ABC Viable Concepts • Alternatives for construction • Construction during non-peak hours • Nighttime closures • Week-end closures • Total or partial closures • Lane closures or detours • Public relations: keep traveling public, businesses, politicians, etc informed

  8. Why ABC-PBES? ABC-PBES offers significant advantages over Cast-in-place construction. ABC-PBES results into: • Reduced onsite construction time • Minimized traffic disruption – from months to days • Reduced Environmental impact • Improved work zone safety – improved worker safety • Lower First and Life-Cycle Costs • Improved product quality – controlled environment, cure times, easier access, etc.

  9. Prefabricated Bridges to Accelerate ConstructionSurvey to Sample State Bridge Engineers Question: Barriers to routinely install PBES in hours or days?

  10. Prefabricated Bridges to Accelerate ConstructionSurvey to Sample State Bridge Engineers Question: What would help most to use PBES?

  11. Prefabricated Bridges to Accelerate ConstructionSurvey to Sample State Bridge Engineers • Questions: • Barriers to routinely install PBES in hours or days? • What would help most to use PBES?

  12. Framework for PBESDecision-Making Users • Decision makers for bridge type • Implementers • Designers • Project Managers

  13. Framework for PBESDecision-Making – Format • Introduction • Flowchart • Decision-Making at a Glance • Matrix • Decision-Making Questions • Decision-Making Considerations • Questions with Discussion and References

  14. Framework for PBESDecision-Making – In General • PBES are better • Due to improved quality control off-site and off-the-critical-path fabrication • PBES are faster • PBES are safer • PBES have lower initial costs • Due to significantly reduced traffic control, risks, environmental impacts, user delay costs

  15. Framework for PBES Decision-Making Specific Project Considerations • Better • Faster • Safer • Is prefabrication the best solution for this specific project ? • Lower initial costs ? • Long lasting ?

  16. Decision Making A T A G L A N C E Flowchart

  17. RAPID ONSITE CONSTRUCTION FACTORSTraffic Volume / Emergency / Commerce / User Delay ???

  18. OTHER FACTORSWorker Safety / Wetlands-Air Quality-Noise /Endangered Species / Multiple Similar Sections ???

  19. PBES CONSTRUCTION COSTS LESS ???

  20. A T A G L A N C E Decision Making

  21. Decision-Making Matrix Example Questions

  22. Decision-Making Matrix • One or two factors may warrant use of PBES • Alternatively, user may assign weights to factors • In any case, a majority of “Yes” responses indicates PBES offers advantages

  23. Considerations in Selecting PBES – Categories • Rapid Onsite Construction Factors • Other Factors • Costs Factors

  24. Considerations Category:Rapid Onsite Construction • High ADT/ADTT? • Emergency bridge replacement? • Evacuation route, or over a railroad or navigation channel? • Requires lane closures, detours or temporary bridge? • If closed, or detour distances long? • Impacts critical path of total project?

  25. Considerations Category:Rapid Onsite Construction, cont’d. • Close during off-peak traffic periods? • Requires rapid recovery from natural or manmade hazards, or rapid completion of future repair/rehab? • Construction time restrictions due to adverse economic impact? • Weather limits CIP construction? • Are spans under 200 ft.?

  26. Considerations in Selecting PBES – Categories • Rapid Onsite Construction • Other Factors • Safety Concerns • Environmental Issues • Standardization • Site Issues

  27. Considerations Category:Other Factors • Safety Concerns • Worker safety concerns? (e.g. adjacent power lines, high heights, or over water) • Environmental Issues • Environmentally sensitive area? (e.g. wetlands, air quality, and noise) • Natural or endangered species? • Historic bridge?

  28. Considerations Category:Other Factors, cont’d. • Standardization • Multiple similar spans? • Bridges grouped for economy of scale • Available state or national prefabricated bridge standards? • Regional off-the-shelf components using stockpiled standards? • Incorporation of aesthetic or context-sensitive design requirements?

  29. Considerations Category:Other Factors, cont’d. • Site Issues • Problems with delivery of ready-mix concrete? • Knowledgeable available contractors? • Available prefabricators? • Contractor options for prefabrication? • Delivery to the site?

  30. Considerations Category:Other Factors, cont’d. • Site Issues, cont’d. • Accessibility at the site? • Prefab foundations & substructures? • Formwork & falsework requirements? • Straight/skewed/curved alignment? • Requires seismic connections? • Available connection details?

  31. Considerations in Selecting PBES – Categories, cont’d. • Costs • Maintenance of Traffic • Contractor’s Operations • Owner Agency’s Operations • Service Life • Available Online Resources

  32. Considerations Category: Costs • Maintenance of Traffic • Changing traffic control plan? • Delay-related user costs a concern? • Contractor’s Operations • Innovative contracting strategies? • Use of innovative equipment? • Contractor costs for insurance/bonding?

  33. Considerations Category:Costs, cont’d. • Owner Agency’s Operations • Necessary staffing? • Bridges grouped for economy of scale? • Broader use? • Adequate prefabrication time in contract? • Service Life

  34. FHWA Decision-Making Framework

  35. Utah DOT Decision Chart

  36. Framework Available Online General Information • http://www.fhwa.dot.gov/bridge/prefab/ Publications • Framework For PBES Decision-Making

  37. Why Use PBES Technologies? • Prefabricated Bridge Advantages: • Faster (offsite & off critical path) • Safer (for traveling public & construction & inspection personnel) • Better Quality (controlled environment) • Lower Cost (Costs comparable to or lower than conventional construction)

  38. Polling Question #1 • Select the items that are ABC Viable Concepts. • Prefabrication of standard elements • Cast-in-place is planned on bridge alignment • Pre-assembly • Off site assembly • Weekend or night time closures are planned.

  39. Polling Question #2 • Select the obstacles to installing PBES in hours or days. • Lack of education and training • Lack of standards & specifications • Construction industry is geared up for prefab • Potential higher cost & limited resources • Durability is not a concern

  40. Polling Question #3 • Select the major components of the PBES decision making framework. • Decision-making flowchart • Life cycle cost analysis tool • Decision-making matrix of questions • Decision-making consideration questions and discussions • All of the above

  41. Polling Question #4 • Select the items that are onsite construction factors. • Low traffic volumes • Emergency repair project on high ADT route • Project has negative impact on major industry • Highway work is on the critical path of project and bridge is not. • There are significant user delays if lane is closed for construction.

  42. Polling Question #5 • If rapid onsite construction is not required for a project, select the other factors that may make prefabrication the preferred solution. • Bridge is high over the water and near high voltage lines. • Endangered species • Wetlands • Repetitive superstructure spans and substructure types • All of the above

  43. Summary and final concluding remarks Use PBES Decision-Making Framework to help accelerate bridge construction and help change America’s driving experience and meet the customers’ needs. Claude Napier, Senior Structural Engineer 804-775-3327, claude.napier@dot.gov • Louis Triandafilou, Senior Structural Engineer • 410-962-3648, lou.triandafilou@dot.gov Resource Center, Structures TST

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