D2-Decision Deck project Workshop, March 8-9, 2007 , University of Luxem bourg. A multi-criteria approach for asset management of waste water networks Am ir NAFI, Caty WEREY Joint Unit Research in Water Utilities Managem ent Cem agref-Engees 1 1 quai Koch 670 70 Strasbourg, France.
Context Data Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion Context Context Context 152 sewerage utilities Joint international conference on com puting and decision m aking in civil and building engineering - june 1 4 -1 6 2 0 0 6 - Montreal 2
Context Data Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion Context Sewers inventory in 2003: � Data base called CHIMERE Data on the Defects noticed by pipe and its CCTV inspections under « local » environm ent codification 5 1 0 0 km 3 2 2 3 2 inspections ( 4 6 0 0 km 8 9 3 1 1 defects w aste w ater) 3
Data Context Context Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion Data « local » codification (extract) CCTV « local » codification (extract) CCTV Defect gravity 1 2 3 4 5 Horizontal fissure x Horizontal fissure, quite all around Horizontal fissure, water infiltration, quite all around Horizontal fissure, water infiltration x Horizontal fissure, visible humidity x Horizontal fissure, visible humidity, quite all around Vertical fissure x 4
Data Context Context Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion Encodage EN 13508- -2 standard codification (2003) 2 standard codification (2003) EN 13508 Defect: Break/collapse Main Aditional information description code BAC characterisation The nature of the observation is: – pieces of pipe visibly displaced - Break (A) – missing pieces of wall - Missing (B) – complete loss of structural - Collapse (C) integrity quantification The length of the observation in millimetres Circumferential location The position of the observation Joint international conference on com puting and decision m aking in civil and building engineering - june 1 4 -1 6 2 0 0 6 - Montreal 5
Data Context Context Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion REREAU RERAU methodology RERAU methodology q Defects : actual physical state of the pipe q Dysfunctions: consequences of defects q I m pacts: effects of the dysfunctions if vulnerability: segment and environment. q Direct observation ( O) : it is the case of CCTV inspection q Observation-based estim ations ( E/ O) : some time results of defects observed by CCTV q Estim ations based on risk factors ( E/ R) : step before CCTV inspection. 6
Data Context Context Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion REREAU Main categories of dysfunctions Main categories of dysfunctions I dentification Dysfunctions INF Infiltration EXF Exfiltration HYD Decrease of hydraulic capacity DEB Flooding DEV Overflow ENS Sand silting BOU Blockage RAC Ongoing degradation from roots EFF intrusion DSC Risk of collapse ATC Destabilisation of ground-pipe system ABR Ongoing corrosion Ongoing degradation from abrasion 7
Data Context Context Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion REREAU RERAU methodology: E/O T criteria valuation RERAU methodology: E/O T criteria valuation Dysfunction I NFI LTRATI ON DYSFONCT INF4-E/O-T indicator , estimated by CCTV inspection Infiltration risk Valuation scale Network and sub -system � segment Valuation type Observed Dysfunction � Observed-based estimation of Dysfunction Estimations of Dysfunction based on risk factors Unit or gravity levels level : 1/2/3/4 1 – coding Ci of observations Oi according standard EN 13508 -2 ; Valuation 2 – translating in Ni of coded observations Ci according following table ; 3 – calculation of density D = N / Lt , with N= Σ Ni, et LT:length of the segment (m); 4 – comparison of D with thresholds S1, S2, S3 : level 1if D ? S1 ; 2if S1 < D ? S2 ; 3 [ S2 < D ? S3 ; 4 [ i S3 < D. 8
Data Context Context Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion Proposition Available data Chim er q Sewers data and CCTV inspections The m ethodolgy m ethodolgy The q EN 13508 standard for dysfunctions EN 13508 standard for dysfunctions encodage encodage q q Using RERAU methodology: Density assess Using RERAU methodology: Density assess q q Calssification of sewers in three main categories q Calssification of sewers in three main categories Good, medium and bad Good, medium and bad Application Application q Use Use mutli mutli- - criteria approach for classification: criteria approach for classification: Electre Electre- - tri method tri method q q Use an assignment example according given by an expert Use an assignment example according given by an expert q q Partial inference: Partial inference: wheights wheights and and profils profils q Decisions Decisions q Investigation plans Investigation plans q q q Rehabilitation Rehabilitation programms programms 9
Data Context Context Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion Proposition Available data Chim er q Sewers data and CCTV inspections RERAU m ethodology EN 1 3 5 0 8 -2 The m ethodology Dysfonctions asses q Using RERAU methodology: Density assess Sew ers q EN 13508 standard for dysfunctions codification hierarchisation q Calssification of sewers in three main categories Muti-criteria Good, medium and bad approach Application Application Electre-Tri q Use Use mutli mutli- - criteria approach for classification: criteria approach for classification: Electre Electre- - tri method tri method q q Use an assignment example according given by an expert q Use an assignment example according given by an expert q Partial inference: weights and profiles Partial inference: weights and profiles q Decisions Decisions q Investigation plans Investigation plans q q Rehabilitation Rehabilitation programms programms q 10
Data Context Context Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion Proposition Available data q Sewers data and CCTV inspections Chim er The m ethodology RERAU m ethodology EN 1 3 5 0 8 -2 Dysfonctions asses q Using RERAU methodology: Density assess q EN 13508 standard for dysfunctions codification q Calssification of sewers in three main categories Sew ers hierarchisation Good, medium and bad Muti-criteria Application approach Electre-Tri q Use mutli-criteria approach for classification: Electre-tri method q Use an assignment example according given by an expert q Partial inference: weights and profiles • I nvestigation plans Decisions • Rehabilitation program s q Investigation plans q Rehabilitation programms 11
Data Context Context Data Encodage Encodage REREAU REREAU Proposition Proposition Conclusion Conclusion Proposition Asset management approach for a given segment q 10 dysfunctions taken into account in decision making, number of criteria equal to 10. q 3 categories , 2 profiles q We consider an assignment problem of 60 sewers , 20 for each category according to expert decision Criteria Sewers I NF EXF HYD DEB DEV ... ENS Category Sew ers S 1 120 20 30 40 50 60 Good Categories S 2 120 20 30 40 50 60 Good . . . . . . . . . . . . . . . . S 60 120 20 30 40 50 60 Medium 12
Conclusion Data Context Context Data codification codification REREAU REREAU Proposition Proposition Conclusion Conclusion January 2 0 0 7 – May 2 0 07 q encoding data available : last year - 2006 q RERAU methodology and density calculation for each criterion q assignment example: expert asses, sample of 60 segments q determination of profiles and weights of criteria : IRIS q application to extended set of sewers in order to propose rehabilitation programs q implementation of the method in sewer utility 13
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