Bridge Management

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Bridge Management

• John Weaver
• Deighton Consulting Group
• July 10, 2002

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Overview

• Planning Needs Analysis
• Data
• Models and Concepts
• Analysis

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Bridge Management

• WHICH
• WHEN
• WHAT
• HOW MUCH

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Planning Level BMS

• How much is needed in Bridge Investment
• Shows cash flow over time
• Standard data
• Matches PMS type planning
• Major Treatment, Need Year and
• Not Project Level

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Network vs. Project
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Data
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NBI Ratings

• Major Items Rated 0 9 scale
• Superstructure
• Substructure
• Deck
• Overall Structural Adequacy
• Geometry Measures recorded
• Load Capacity Calculated
• All Standardized in NBI Manual

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Bridge Data
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Indexes

• FHWA Sufficiency rating
• 100 to 0 Scale and used in funding

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Health Index

• Each Measure has different scales
• Tons, Feet, Rating, Miles
• Need to be combined into overall index for
  measure of effectiveness

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Health Index

• Health Index
• 100 (ConditionDVWt TonsDVWt)
• (100 Sum of Deduct Values)
• Each Index, Measure or Rating is given a
  Disutility or deduct value and then subtracted
  from 100.
• Same concept as deduct values for pavement
  distress deducted from 100

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Example of Deduct
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Load Capacity
1 ton less than Full Rating gives 20 Deduct point
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Example of Clearance
VCa Vert Clear Actual VCp Vert Clear preferred
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Treatments

• Generalized Treatments and Costs
• Examples
• Deck Rehab
• Superstructure Rehab/Strengthening
• Deck Replacement
• Ancillary Treatments
• Widening
• Substructure Repair
• 15 Major treatments

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Major Decision Elements

• Structural Evaluation
• Vertical Clearance over Road
• Horizontal Clearance under Bridge
• Vertical Clearance under Bridge
• Load Capacity (Inventory Rating)
• Substructure Condition
• Superstructure Condition
• Deck Condition
• Wearing Surface
• Deck Geometry

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Treatment Filter Example
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Example Curve
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Analysis

• Enough about details
• Models and details can all fit within CT
• Can be a complex as you care
• Template created with
• 15 treatments, plus ancillaries
• 30 Analysis variables
• 50 year life-cycle

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Results
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Condition Distribution
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How Much

• How much is needed to maintain conditions is
  probably the biggest question
• The Return on Investment Graph is an important
  tool
• Most management is more interested in the this
  question
• Note Use Committed projects for the special
  projects and situations

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Data for RoI Graph
Multiple Budget Scenarios Analyzed At 20 Years,
Sum of all selected candidate strategies At 20
Years, the Average Network Conditions Divide the
Sum by 20 to get the Average Expenditure
DATA
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Return on Investment
Tells you How much is needed to improve
conditions A Budget level approximation How much
to put into a Sinking Fund A base line for
discussions with Budget agency
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Summary

• Bridges are just another Perspective
• Bridge analysis formulated on NBI data
• Short Range Planning at the network level
  outcomes for bridges
• Project level still needs engineering
• Special Bridges handled separately
• dTIMS CT is ready to provide answers