ABC Decision Matrix Presenters Timothy D. Fields, P.E. Transportation Principal Engineer Bridge Consultant Design Ashley Heredia Transportation Engineer II Bridge Design 1
Connecticut DOT s ABC Decision Process ABC Decision Matrix developed as a collaborative process with major assistance From Mike Culmo, P.E. with CME Associates Matrix used on pilot basis during refinement prior to official release ABC Decision Matrix officially issued for mandated use in CTDOT bridge projects, November 2017 Now used in preliminary design of all bridge projects involving replacement of bridge deck, superstructure, and entire bridge 2
COMPLETED & CURRENT ABC PROJECTS 29 Bridge Replacement Projects o 4 GRS-IBS Substructure Elements o 23 Precast/Prefabricated Elements o 2 Self-Propelled Modular Transporters (SPMT s) 4 New Bridge Projects o 3 GRS-IBS Substructure Elements o 1 Precast/Prefabricated Elements 51 ABC Projects 39 Used ABC Matrix 18 Deck/Superstructure Replacement Projects o 7 Modular Deck Beams (PBU s) o 7 Precast Deck Panels o 2 Self-Propelled Modular Transporters o 1 Design-Build o 1 Superstructure replacement with lateral slide 3
ABC Decision Matrix Experience ABC Decision Matrix (including earlier drafts) used in 39 CTDOT projects involving replacement of bridge deck, bridge superstructures or entire bridges ABC Decision matrix project ratings lead to decision to use ABC construction methodology in 23 of these ABC rated projects (59%) CTDOT generally satisfied with ABC ratings project generated Will reassess ABC rating table weight factors in near future 4
Sample ABC Decision Matrix Input variables include Construction duration for both ABC and conventional, ADT of the roads impacted, approximate cost for both conventional and selected ABC construction type, and other bridge location site variables Matrix calculates weighted ABC rating scores for all input variables. Output macro then provides the user with an ABC rating score. (Spreadsheet input in yellow boxes; Spreadsheet output in white boxes) 5
6 ABC Decision Matrix Sheet 1 Enter Site Information data Project description ABC construction method Conventional Construction method Enter following traffic inputs for Roadway on Bridge and Roadway Below Bridge(if applicable) for both Conventionaland ABCalternatives for determination of user impact reduction: ADT Delay Time (entered from supplementary traffic delay time spreadsheets) Construction Impact duration Spreadsheet calculates User Impact Reduction value for ABC compared to Conventional Construction
Alternating Traffic Delay Time (Supplementary Spreadsheet) Determine and Enter estimated cycle time 7
Detour Length Delay (Supplementary Spreadsheet) 8
Reduced Lane Delay Time (Supplementary Spreadsheet) 9
10 ABC Decision Matrix Sheet 2 Entire following project inputs: Conventional Project Cost Overbuild Req d base bridge costs CE&I Monthly costs Field office CE&I staff ABC Net time savings ABC estimated add lcost premium MPT (Maintenance & Protection of Traffic) cost savings with ABC Overbuild not needed Temporary bridge not needed Temporary signal not needed Other Spreadsheet calculates the ABC premium as a Net Percentage of conventional cost
ABC Decision Matrix Sheet 3 Enter project rating values: Average Daily Traffic Bridge Location Use of Typical Details Work Zone Geometry Site Conditions Railroad Impacts User Impact Reduction is internally computed from data input on Sheet 1 11
ABC Decision Matrix Sheet 4 Enter Project rating values: Cost Analysis Factor Environmental Water Handling Waterway Limitations (ABC Rating Table -discuss next slide) 12
ABC Decision Matrix Sheet 4 (Continuation) ABC Rating Table ABC Rating table computes comparative rating for ABC project methodology under consideration Rating Table Compiles all selected or computed rating measures Multiples rating measures by weighting factors Divides sum of weighted measure by theoretical maximum to produce ABC rating score Rating Scores 60-100 -Use ABC 50-60 -Consider ABC 13 0-50 -ABC not favorable
ABC MATRIX EXAMPLE Project 0103-0265 Replacement of Bridge No. 02589 City of Norwich 14
15 Bridge Background Information
15 Bridge Background Information
15 Bridge Background Information
Bridge Background Information Two wingwalls are leaning towards the channel. Temporary steel supports had to be added between the two wingwalls Heavy laminated rust with locations of section loss and reduction of width to beam bottom flanges 16
Structure Type Considerations Wingwall Replacement: Least expensive option Didn t address the scour issue or superstructure deficiencies. Substructure rating would only go up to a 5. Considered a short term fix. Structure Replacement Culvert: Significant amount of wetland impacts DEEP (CT Department of Energy and Environmental Protection) did not approve of the flat bottom Because structure is near a river, the flood zone covered the structure and the culvert alternative would result on a net fill of material which would potentially impact the river. Structure Replacement Three-sided structure: Natural channel bottom which was preferred by DEEP Reduced wetland impacts Regarding flood zone concerns, there would be no net fill of material impacting the river 17
Structure Type Considerations Both alternatives had lower environmental impacts. Precast rigid frame, footings, and wingwalls Both alternatives worked in terms of geometry and span. Which alternative to go with? Integral abutment with cast in place deck and parapet; precast abutments and wingwalls 18
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26 Project No. 152-157 (2016) I-95 over Oil Mill Rd, Waterford Superstructure Replacement using Lateral slide
27 Project No. 93-200 (2017) Rte175 over Amtrak RR, Newington Superstructure Replacement using Modular Deck Beams (or PBU s)
Questions g{tç~ çéâ Web address to CTDOT ABC Decision Matrix https://www.ct.gov/dot/lib/dot/documents/aec/eb-2017-6.pdf 28