Chapter 8 Condition Assessment Inspection Model

1
Chapter 8 Condition Assessment (Inspection)
Model

• The condition assessment model is a set of
  protocols that
• identifies the culverts, which are
  underperforming
• determines the reasons for its deficiency
• predicts when failure is likely to occur
• develops short and long-term plans for their
  preservation
• The condition assessment model is divided into
  two categories
• Basic Condition Assessment
• Advanced Condition Assessment

2
Basic Condition Assessment

• The basic condition assessment is the general
  inspection of the culvert, its components and
  surrounding area.
• The assessment begins with recording the general
  identification of the inspection site and the
  culvert structure.
• Then the various components of the culvert are
  inspected for defects against a condition rating
  system.

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Basic Condition Assessment (Contd)

• The culvert and its components are assigned a
  condition rating according to the following table

4
Basic Condition Assessment (Contd)

• Using AHP, relative weights for these components
  are assigned and culvert performance score is
  calculated.
• Based on the performance score, the culvert is
  categorized into three zones
• Critical Zone (Red Zone) The culverts in this
  zone are in the verge of failure and need
  immediate attention
• Monitored Zone (Yellow Zone) The culverts in
  this zone are in intermediate stage. They should
  be taken care after the culverts in Critical zone
  are addressed
• Satisfactory Zone (Green Zone) The culverts in
  this zone are safe and free from deterioration.
• Culverts which fall in the danger zone are
  further investigated for Advanced Condition
  Assessment

5
Basic Condition Assessment (Contd)

• Module 1 General Information
• State Code
• County Code
• Place Code
• Culvert Identification Number
• Year Built
• Date of Inspection
• Inspectors Name
• Maintenance Responsibility

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Basic Condition Assessment (Contd)

• Module 2 Culvert Site Information
• Inspection Season
• Climate
• Time of Inspection
• Type of Stream
• Type of Inspection
• Water Level
• pH of Water
• Soil Resistivity
• Vegetation
• Natural Hazards

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Basic Condition Assessment (Contd)

• Module 3 Identification of Culvert
• Shape
• Material
• Number of Cells
• Type of End Treatment
• Geometric Dimensions

8
Basic Condition Assessment (Contd)

• Module 4 Condition Assessment of the Culvert
• Condition of the invert

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Basic Condition Assessment (Contd)

• Condition of End Protection

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Basic Condition Assessment (Contd)

• Condition of the Roadway

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Basic Condition Assessment (Contd)

• Condition of the Embankment

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Basic Condition Assessment (Contd)

• Condition of the Footings

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Basic Condition Assessment (Contd)

• Overall Condition of the Culvert

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Basic Condition Assessment (Contd)

• Module 5 Calculation of performance score
• Step 1 Each culvert component selected above is
  pair wise compared with remaining components in
  its importance on the overall performance of the
  culvert

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Basic Condition Assessment (Contd)

• Step 2 Matrix of comparison is developed after
  all pair wise comparisons are made as shown
  below

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Basic Condition Assessment (Contd)

• Step 3 Normalizing the Pairwise Comparison
  Matrix by summing all the elements in a column
  and dividing each element in that column by this
  sum

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Basic Condition Assessment (Contd)

• Step 4 Adding all elements in a row of the
  normalized matrix and dividing it by the number
  of elements in that row.

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Basic Condition Assessment (Contd)

• Module 6 Categorizing culverts based on their
  performance.
• The formula for calculating performance score of
  the culvert is
• Performance Score of the culvert S Condition
  Rating x Relative Weight

19
Basic Condition Assessment (Contd)

• Based on the performance score, the culvert is
  zoned into three categories Critical (Red),
  Monitored (Yellow) and Satisfactory (Green).

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Advanced Condition Assessment (ACA)

• Any culvert with a performance score below 2.5 is
  inspected for specific problems, which has caused
  decay.
• The objective of ACA is to have a condition
  rating system for problems causing deterioration
  specific to concrete, metal and plastic culverts
• The assessment begins with the detailed
  inspection at the inlet, outlet and inside the
  culvert pipe.
• The condition rating system between 5-0 is used
  as a benchmark in identifying the problems

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Advanced Condition Assessment (Contd)

• Using AHP relative importance weights are
  calculated for all the culvert problems as
  follows
• ACA Condition Rating Factors and their Relative
  Weight for Concrete Culverts

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Advanced Condition Assessment (Contd)

• ACA Condition Rating Factors and their Relative
  Weight for CMP

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Advanced Condition Assessment (Contd)

• Performance score for the culvert is calculated
  using the following formula
• ACA Performance Score of the culvert S ACA
  Condition Rating x Relative Weight
• The inspector recommends repair or renewal to fix
  the specific problem causing culvert
  deterioration.

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Advanced Condition Assessment (Contd)

• After the culvert is treated, performance score
  is calculated to check the percent performance
  improvement in the culvert using the following
  formula
• Percent Performance Improvement
• Performance score after the culvert
  is repaired or rehabilitated
• Performance score when the culvert
  problem was identified or before repair or
  renewal of the culvert