A GIS-Based Decision Support System for Optimal Renewal Planning of Sewers
INFRA 20075-7 November
2007Québec
Mahmoud Halfawy, Leila Dridi, & Samar Baker
NRC-Centre for Sustainable Infrastructure Research
2November 6, 2007
Background
• Fragmentation of sewer management data and processes.
• Need for proactive and optimized renewal planning.
• State-of-practice in sewer management software.
• Challenges for integrating sewer management data, processes, and software systems.
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NRC-CSIR Integrated Asset Management Project
• Objective:– Develop consistent/generalized models and protocols for asset
management process systematization and data integration – Bridging the vertical (departmental) and horizontal (cross-disciplinary) gaps.
– Develop algorithms and a set of interoperable GIS-based decision support tools for optimizing and coordinating asset management plans for water, sewer, and road networks.
• Project Partners: City of Regina.
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Inspection/Monitoring
Condition Assessment
Risk Assessment
Deterioration Modeling
Performance Modeling
Asset Prioritization
Rehab Methods
Renewal Planning
Inspection/Monitoring
Condition Assessment
Risk Assessment
Deterioration Modeling
Performance Modeling
Asset Prioritization
Rehab Methods
Renewal Planning
Maintenance Mgt
Condition Assessment
Risk Assessment
Deterioration Modeling
Performance Modeling
Asset Prioritization
Rehab Methods
Renewal Planning
Optimized & Coordinated Plans
Vertical Integration
Horizontal Integration
Integration of Municipal Asset Mgt Processes
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The Renewal Planning Step-Wise
Algorithm
Year = 1
Calculate condition index
Calculate risk index
Calculate prioritization ranking
Select feasible rehabilitation options
Prepare Asset Data Repository
Define planning horizon
Specify condition/risk minimum
requirements
Specify budget scenario
Specify budget scenario
Specify option criteria & run MOO & calculate
Pareto fronts
Select a satisfying solution
Revise budget scenario and/or condition/risk requirements
Create Delta Tables
yesno Print
Renewal plan for
one scenario
Print Renewal plan for
one scenario
yes
no
Year = Year + 1
End
Apply Delta Tables
Solution found?
Year = horizon?
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GIS and Data Management Services
Intranet/Extranet
Sewer Management Stakeholders
Integrated Asset Data Repository
Spatial and Inventory Data
Performance Data
Maintenance and rehabilitation Data
Financial/Cost Data
Deterioration/Life cycle cost Data
Simulation Models/Results
Inspection and Condition Data
References to other databases (ERP, CIS, SCADA, etc.)
Work Order and Operational Data
Data and Process Integration Using Centralized Shared Repositories
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ESRI Classes::ComplexEdgeFeature ESRI Classes::SimpleJunctionFeature
«SubtypeField» -Subtype : esriFieldTypeInteger = 1-FacilityID : esriFieldTypeString-InstallDate : esriFieldTypeDate-LifecycleStatus : ssDomainLifecycleStatus = Active
Sewer/Stormwater Line Abstract Class::SewerLine{GeometryType = esriGeometryPolyline}
-Depth : esriFieldTypeInteger-Diameter : ssDomainPressurizedMainDiameter-GroundSurfaceType : esriFieldTypeString-PressureRating : esriFieldTypeString
Network Feature Class::Force-CrossSectionShape : ssDomainGravityMainShapes = Circular-UpstreamInvert : esriFieldTypeDouble-DownstreamInvert : esriFieldTypeDouble-Diameter : ssDomainMainDistributionDiameter = 0-Slope : esriFieldTypeDouble
Network Feature Class::ssGravityMain
-Subtype : esriFieldTypeInteger = 1
ssGM Subtype::Main
-Subtype : esriFieldTypeInteger = 2
ssGM Subtype::Trunk
Subtype
«SubtypeField» -Subtype : esriFieldTypeInteger = 1-FacilityID : esriFieldTypeString-InstallDate : esriFieldTypeDate-LocationDescription : esriFieldTypeString-LifecycleStatus : ssDomainLifecycleStatus = Active-Elevation : esriFieldTypeDouble
Facility Abstract Class::SewerFacility
-InstallationDate : esriFieldTypeDate-MaintainedBy : esriFieldTypeString-RimElevation : esriFieldTypeDouble-SumpElevation : esriFieldTypeDouble-Material : esriFieldTypeString-Enabled : bool = True-Revisit : bool = False-Comments : esriFieldTypeString
Network Feature Class::ssManhole
-Material : ssDomainSewerMaterial-Diameter : esriFieldTypeInteger-StartElevation : esriFieldTypeDouble-StartElevationDescription : esriFieldTypeString = INV-EndElevation : esriFieldTypeDouble-EndElevationDescription : esriFieldTypeString = INV-InstallationDate : esriFieldTypeDate-InstalledBy : esriFieldTypeString-maintainedBy : esriFieldTypeString-FinalBook : esriFieldTypeString-Status : ssDomainLifecycleStatus = ACTIVE-Revisit : esriFieldTypeString-SurveyedLength : esriFieldTypeDouble = 0.0-StreetKeyNumber : esriFieldTypeString
Sewer/Stormwater Line Abstract Class::SewerLine
-InspectionDate : esriFieldTypeDate-InspectionCrew : esriFieldTypeString-Contractor : esriFieldTypeString-CCTVFileName : esriFieldTypeString-TapeNumber : esriFieldTypeString-VCRCount : esriFieldTypeInteger-TotalTime : esriFieldTypeDouble-SheetNumber : esriFieldTypeInteger-ReportNumber : esriFieldTypeInteger-StartMHID : esriFieldTypeOID-EndMHID : esriFieldTypeOID-StreetName : esriFieldTypeString-FromStreet : esriFieldTypeString-ToStreet : esriFieldTypeString-CameraDirection : esriFieldTypeString-FlowDirection : esriFieldTypeString-WRCRating : esriFieldTypeDouble
CCTVInspectionRecord
-InspectionDate : esriFieldTypeDate-SheetNumber : esriFieldTypeInteger-StartPoint : esriFieldTypeDouble-EndPoint : esriFieldTypeDouble-DefectCode : esriFieldTypeString-Description : esriFieldTypeString-Severity : esriFieldTypeString-Score : esriFieldTypeInteger
CCTVAssessmentRecord
-NumberOfInspectionRecords : esriFieldTypeSmallInteger
CCTVInspectionRecordsAssociationClass
11..*
Sewe
rInsp
ectio
nRec
ordsA
ssoc
iation
-SewerID : esriFieldTypeOID-InletNodeID : esriFieldTypeOID-OutletNodeID : esriFieldTypeOID-Description : esriFieldTypeString-Tag : esriFieldTypeString-Shape : esriFieldTypeString-MaxDepth : esriFieldTypeDouble-Length : esriFieldTypeDouble-Roughness : esriFieldTypeDouble-InletOffset : esriFieldTypeDouble-OutletOffset : esriFieldTypeDouble-InitialFlow : esriFieldTypeDouble-MaxFlow : esriFieldTypeDouble-EntryLossCoeff : esriFieldTypeDouble-ExitLossCoeff : esriFieldTypeDouble-AvgLossCoeff : esriFieldTypeDouble-FlapGate : bool = NO-HydraulicConditionRating : esriFieldTypeDouble
SewerHydraulicAttributes-SewerID : esriFieldTypeOID-GroupID : esriFieldTypeSmallInteger-MostRecentInspectionDate : esriFieldTypeDate-MostRecentConditionRating : esriFieldTypeDouble-DeteriorationModelID : esriFieldTypeSmallInteger-RemainingServiceLife : esriFieldTypeDouble-ProbabilityOfFailure : esriFieldTypeDouble-RiskAssessmentFormulaID : esriFieldTypeSmallInteger-RiskFactor1 : esriFieldTypeDouble-RiskFactor2 : esriFieldTypeDouble-RiskFactor3 : esriFieldTypeDouble-RiskFactor4 : esriFieldTypeDouble-RiskFactor5 : esriFieldTypeDouble-RiskFactor6 : esriFieldTypeDouble-RiskFactor7 : esriFieldTypeDouble-RiskFactor8 : esriFieldTypeDouble-RiskFactor9 : esriFieldTypeDouble-RiskFactor10 : esriFieldTypeDouble-RiskFactor11 : esriFieldTypeDouble-WeightedRiskFactor : esriFieldTypeDouble-RiskIndex : esriFieldTypeDouble
SewerRiskAssessmentAttributes
Sewe
rHyd
raulic
Mode
lAsso
ciatio
n
Sewe
rRisk
Asse
ssme
ntRec
ordAs
socia
tionPart of the UML
class diagram for the integrated sewer data model
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Renewal Planning Algorithm Implementation
• Define an integrated data model and build asset data repository (inventory, hydraulic data, condition data, repair/incidence records, risk parameters, cost data, service levels, etc.).
• Define an integrated condition rating index.• Define /calibrating deterioration curves.• Define risk assessment model.• Define asset prioritization criteria.• Define renewal technologies database, and algorithm for selecting
feasible options.• Define a multi-objective optimization (MOO) algorithm (maximize
condition, minimize risk, and minimize budget).
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Sanitary sewers and Vitrified Clay (2881 records)
Sanitary sewers and pipe condition = 3 (823 records)
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Deterioration Modeling
• Largely depends on the quantity and quality of available condition data. – May use deterministic or probabilistic models– Employs many different techniques: regression analysis, Markov
processes, ANN, fuzzy models, etc.
• Our approach:– Store a library of known or previously calibrated models– If a sewer or a group has sufficient data to do regression analysis, define
a new model or calibrate an existing model.– If data is not enough, assist user to select a “suitable” model based on
his/her intuition/experience with the system and the data available.– As more data become available, the models can be re-defined or re-
calibrated.
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Condition, Risk & Prioritization Analysis Tool
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Risk Assessment & Prioritization Models
• Risk = Consequence of Failure * Probability of Failure• Criticality factors affecting consequence of failure:
– Sewer type, diameter, depth, embedment soil, land use, road classification, traffic volume, proximity to critical assets, socio-economic impact, site seismicity, etc.
• Procedure:– Calculate a Risk Factor (1-5 scale) that reflects the consequence of failure
using a weighted average equation.– Calculate the likelihood of failure index (LFI) for the sewer, based on its
current age and expected service life.– Risk Index = RF * LFI
• Prioritization ranks sewers based on their “priority index” (1-5 scale) to select candidates for renewal.
• Priority index is derived from the condition index and risk indices according to a set of user-defined rules.
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Renewal Methods Selection Tool
• Applicability criteria for method selection:– Sewer characteristics (diameter, material, depth, type: gravity or
pressure, structural condition state, hydraulic capacity, etc.)– Method characteristics (renewal type (NS/SS/FS), limitations, site and
installation requirements)– Site characteristics (soil type, traffic, water table, etc.)
• Cost vs. Condition Improvement:– Expected condition improvement– Technology construction cost – Technology overall cost (socio-economic cost)– Expected operational cost after improvement
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Renewal Methods Selection Tool (Cont.)
Pipe Bursting
Pipe Removal
Replacement
Sliplining
CIPP
Close fit pipe
Formed in place
Thermoformed
Spiral wound
Panel lining
UCL
Fully Structural
Semi-Structural
Non-Structural
Renewal Technologies
Open-Cut(Dig) In-Line Off-Line
Horizontal Directional Drilling
(HDD)
Pipe Jacking
Micro-Tunelling
Auger Boring
Rehabilitation - Lining
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GA-Based Multi-Objective Optimization Tool
• Trade-offs of the renewal costs vs. network condition and risk improvements.
• Three objective functions for cost, condition, and risk.
• Solution using the NSGA II algorithm and the Open Beagle class library.
• Calculate 2 Pareto fronts for condition-cost and risk-cost criteria.
• Evaluate feasible solutions and select or synthesize a solution.
Network Average Condition/Risk Index
Budget RangeBudget
5
4
3
2
1
Min Condition/Risk Index Limit
S2S3
S4
Dominated Solution
S1
S5
Network Average Condition/Risk Index
Budget RangeBudget
5
4
3
2
1
Min Condition/Risk Index Limit
S2S3
S4
Dominated Solution
S1
S5
Network Average Condition/Risk Index
Budget RangeBudget
5
4
3
2
1
Min Condition/Risk Index Limit
S2S3
S4
Dominated Solution
S1
S5
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Conclusions & Future Work
• Integrated approaches and DSSs are critical for supporting proactive asset management strategies.
• The proposed approach and software prototype provided promising results.
• Work is ongoing to refine/improve several models employed in the prototype, and to validate the software with more data sets. These activities are conducted in collaboration with the City of Regina as well as other industry partners.
• The software modular architecture facilitated incremental development and testing, and would also facilitate future extensions, refinement, and interoperability with other (e.g. legacy) software systems.
• Need to define an industry-wide agenda for developing and adopting open/standard integrated data & process models, and software architectures.
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