On the influence of input data uncertainty on sewer deterioration models – a case study in Norway

Figures & data

Figure 1. Schematic illustration of the applied method.

Figure 2. Bar chart showing the deviation between this project's and professional pipe inspector’s condition classification of the same CCTV video and the derived uncertainty matrix showing the probability of a pipe to be really in condition y when inspected in condition x.

Table 1. Uncertainty matrices for scenario 3 and 4.

Scenario 3		Pipe is inspected in condition class
		1	2	3	4	5
Pipe is actually in condition class	1	0.705	0.240	0.090	0.008	–
	2	0.127	0.465	0.150	0.082	0.008
	3	0.088	0.127	0.465	0.150	0.082
	4	0.063	0.088	0.127	0.465	0.150
	5	0.017	0.080	0.168	0.295	0.760
Scenario 4		Pipe is inspected in condition class
		1	2	3	4	5
Pipe is actually in condition class	1	0.852	0.852	0.159	0.061	0.061
	2	0.106	0.106	0.673	0.125	0.125
	3	0.042	0.042	0.168	0.814	0.814

Table 2. Uncertainty matrix for scenario 1 and 2.

Scenario 1/2		Pipe is inspected in condition class
		1	2	3	4	5
Pipe is really in condition	1	0.625	0.100	–	–	–
	2	0.200	0.525	0.100	–	–
	3	0.100	0.200	0.525	0.100	–
	4	0.050	0.100	0.200	0.525	0.100
	5	0.025	0.075	0.175	0.375	0.900

Table 3. Distribution (%) of installation periods and observed CC for concrete pipes.

Installation period	All pipes [%]	Inspected pipes [%]	Observed condition [%]
			1	2	3	4	5
before 1900	0.07	0.08	28.57	–	42.86	–	28.57
1900-1919	0.34	1.34	13.91	10.43	18.26	26.09	31.30
1920-1939	1.56	3.54	15.18	10.56	13.86	19.47	40.92
1940-1959	7.62	13.16	27.26	14.30	16.52	22.47	19.45
1960-1979	45.66	52.24	38.29	21.42	18.46	13.72	8.10
1980-1999	27.47	18.79	78.16	10.77	5.91	2.49	2.68
2000-	17.28	10.84	94.61	2.16	1.94	0.54	0.76
All	100.00	100.00	49.28	15.84	13.91	11.69	9.27

Figure 3. Condition probabilities of the calibrated GompitZ model with IFF and the corresponding uncertainty bands for the four defined scenarios.

Figure 4. Condition probabilities of the calibrated marginal GompitZ model and the corresponding uncertainty bands for the four defined scenarios.