106 Part II: Multi-state deterioration modelling Table II.2: Damage codes and severity levels available in the inspection dataset from 1993 to 2016 (ϖ indicates damages codes used in this dissertation). Description Code k =1 k =2 k =3 k =4 k =5 Total Infiltrationϖ BBF 16 61,694 8,078 2,818 324 72,930 Displaced joint BAJ 20 1,545 379 239 36,867 39,050 Surface damageϖ BAF 153 30,161 2,880 522 449 34,165 Water level BDD 1,517 16,818 1,301 161 53 19,850 Defective connection BAH 4 3,118 1,233 3,791 4,173 12,319 Protruding inlet BAG 7,405 0 2,326 0 377 10,108 Crackϖ BAB 47 606 0 3,581 5,848 10,082 Roots BBA 0 6,219 1,517 506 697 8,939 Soil penetration BBD 0 3,586 336 66 51 4,039 Attached deposits BBB 1,877 1,536 291 36 43 3,783 Settled deposits BBC 661 1,926 503 98 102 3,290 Intruding sealant BAI 928 514 1,035 62 84 2,623 Porous pipe BAN 0 0 0 0 1,638 1,638 Curvature in sewer BCC 0 0 0 0 1,260 1,260 Soil exposed BAO 0 0 0 0 810 810 Other obstacles BBE 96 365 129 30 60 680 Visible hollow space BAP 0 0 0 0 480 480 Deformation BAA 6 219 52 19 16 312 Fracture/collapseϖ BAC 1 131 0 57 27 216 Defective repair BAL 3 33 141 0 10 187 Defective lining BAK 0 1 14 125 25 165 Missing masonry mortar BAE 0 9 1 2 1 13 Defective masonry BAD 2 5 0 0 0 7 Exfiltration BBG 0 0 0 0 4 4 in S =↔1, 2, 3, 4, 5, F↗. This chain permits transitions between consecutive states, as in the Chain “Single”, and from any state to the functional failure state (F). Information related to this state, such as fracture/collapse (code BAC), is detailed in Table II.2. This Markov chain structure was proposed in this thesis and is further discussed in Chapter 6. For completeness, Table II.3 lists references specifying the type of Markov structure (“Single” or “Multi”) and whether the Markov chain is inhomogeneous (Inhom.) or homogeneous (Hom.). II.5 References Ana, E. and W. Bauwens (2010). “Modeling the structural deterioration of urban drainage pipes: the state-of-the-art in statistical methods”. In: Urban Water Journal 7.1, pp. 47– 59. doi: 0.1080/15730620903447597.
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