II.4.3 Breda’s case study 101 0 2500 5000 7500 10000 12500 15000 17500 20000 Count Concrete PVC VC Masonry PE HDPE RC PP AC Steel FRP Polyester 72.34% 27.05% 0.37% 0.11% 0.05% 0.04% 0.02% 0.01% 0.00% 0.00% 0.00% 0.00% Figure II.2: Material of sewer mains in the Breda case study, Netherlands (total 25,594 pipes). High-Density Polyethylene (HDPE), Polyethylene (PE), Polypropylene (PP), Reinforced Concrete (RC), Fiberglass Reinforced Plastic (FRP), and Asbestos Cement (AC). Figures II.2 and II.3. Figure II.2 shows the sewer main materials. Figures II.3.(a)- (d) present the categorical variables: sewer main content, function, shape, and system type, while Figures II.3.(e)-(h) depict the numerical variables: pipe width, height, construction year, and length. Regarding the categorical variables, Figure II.2 shows that most pipes are made of concrete (72%) and PVC (27%). Figure II.3(a) indicates content types: Mixed (63%), Rain (21%), and Waste (16%). Figure II.3(b) reveals that 98% are used for transport. Figure II.3(c) shows that most shapes are rounded (94%) with a small percentage ovoid (5%). Finally, Figure II.3(d) indicates almost all sewer mains operate by gravity. For the numerical variables, Figure II.3(e) shows that most pipes are less than 2 meters in width and height, as indicated in Figure II.3(f). Figure II.3(g) indicates that the pipes were built between 1919 and 2016, with the majority constructed around the 1950s. Figure II.3(h) shows that most pipes are up to 75 meters long, with the majority around 40 meters. Figure II.4 provides a visualisation of the covariates in the network in terms of sewer main age, diameter, length, and material. Figure II.5 presents a visualisation of the sewer network in Breda, The Netherlands. Through visual inspection conducted via CCTV at various sections along the sewer main length, and based on European standards EN 13508:1; EN 13508:2, the damage codes and severities—ranging from 1 to 5—present in the sewer mains (if any) are determined. As mentioned, a total of 29,926 inspections were registered for 25,594 sewer mains, with several conditions identified and recorded along the sewer main length per inspection. Table II.2 reports the counts per damage code and severity level in the inspection dataset from 1993 to 2016, where the total corresponds to the cumulative instances per damage code across all inspections.
RkJQdWJsaXNoZXIy MjY0ODMw