abc decision matrix · abc decision matrix ashley heredia transportation engineer ii bridge design...

ABC Decision MatrixABC Decision Matrix

Ashley HerediaTransportation Engineer IIBridge Design

Timothy D. Fields, P.E.Transportation Principal EngineerBridge Consultant Design

Presenters

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Connecticut DOT’s ABC Decision Process

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

• 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

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COMPLETED & CURRENT ABC PROJECTSCOMPLETED & CURRENT ABC PROJECTS

� 29 Bridge Replacement Projectso 4 GRS-IBS Substructure Elementso 23 Precast/Prefabricated Elementso 2 Self-Propelled Modular Transporters (SPMT’s)

� 4 New Bridge Projectso 3 GRS-IBS Substructure Elementso 1 Precast/Prefabricated Elements

� 18 Deck/Superstructure Replacement Projectso 7 Modular Deck Beams (PBU’s)o 7 Precast Deck Panelso 2 Self-Propelled Modular Transporterso 1 Design-Buildo 1 Superstructure replacement with lateral slide

� 51 ABC Projects� 39 Used ABC Matrix

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ABC Decision Matrix ExperienceABC 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

• 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

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Sample ABC Decision MatrixSample 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)

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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 Conventional and ABC alternatives 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

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Alternating Traffic Delay Time(Supplementary Spreadsheet)

Alternating Traffic Delay Time(Supplementary Spreadsheet)

Determine and Enter estimated cycle time

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Detour Length Delay (Supplementary Spreadsheet)

Detour Length Delay (Supplementary Spreadsheet)

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Reduced Lane Delay Time

(Supplementary Spreadsheet)

Reduced Lane Delay Time

(Supplementary Spreadsheet)

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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’l cost

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”10



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

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Enter Project rating values:• Cost Analysis Factor• Environmental Water Handling• Waterway Limitations

(ABC Rating Table - discuss next slide)

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ABC Decision Matrix Sheet 4 (Continuation)ABC Rating Table

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• 0-50 - ABC not favorable 13

ABC MATRIX EXAMPLEABC MATRIX EXAMPLE

Project 0103-0265Replacement of Bridge No. 02589

City of Norwich

Project 0103-0265Replacement of Bridge No. 02589

City of Norwich

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Bridge Background InformationBridge Background Information

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Bridge Background InformationBridge Background Information

Heavy laminated rust with locations of section loss

and reduction of width to beam bottom flanges

Two wingwalls are leaning towards the channel. Temporary steel supports had to be added between the two wingwalls

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Structure Type ConsiderationsStructure 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

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Structure Type ConsiderationsStructure Type Considerations

Precast rigid frame, footings, and wingwalls

Integral abutment with cast in place deck and parapet; precast abutments and wingwalls

� Both alternatives had lower environmental impacts.

� Both alternatives worked in terms of geometry and span.

� Which alternative to go with?

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103-265 ABC Decision Matrix103-265 ABC Decision Matrix

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Project No. 152-157 (2016)I-95 over Oil Mill Rd, WaterfordSuperstructure Replacement using Lateral slide

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Project No. 93-200 (2017)Rte 175 over Amtrak RR, Newington Superstructure Replacement using Modular Deck Beams (or PBU’s)

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Web address to CTDOT ABC Decision Matrix

https://www.ct.gov/dot/lib/dot/documents/aec/EB-2017-6.pdf

g{tÇ~ çÉâ

Web address to CTDOT ABC Decision Matrix

https://www.ct.gov/dot/lib/dot/documents/aec/EB-2017-6.pdf

QuestionsQuestions

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abc decision matrix · abc decision matrix ashley heredia transportation engineer ii bridge design...

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