A method of producing a lined pipeline with an integrity monitoring system, comprising: providing a first section of lined pipe (1A, 1B, 1C) with a first sensor cable (31A, 31B, 31C, 131, 231A, 231B) disposed in a continuous annulus between a first host pipe (11A, 11B, 11C, 111A, 111B, 211A, 211B) and a first pipe lining (13A, 13B, 13C, 113A, 113B, 213A, 213B); providing a second section of lined pipe (1A, 1B, 1C) with a second sensor cable (31A, 31B, 31C, 131, 231A, 231B) disposed in a continuous annulus between a second host pipe (11A, 11B, 11C, 111A, 111B, 211A, 211B) and a second pipe lining (13A, 13B, 13C, 113A, 113B, 213A, 213B); and joining the first pipe lining (13A, 13B, 13C, 113A, 113B, 213A, 213B) to the second pipe lining (13A, 13B, 13C, 113A, 113B, 213A, 213B) using an electrofusion fitting (41A, 41B, 141, 241) configured to enable the first sensor cable (31A, 31B, 31C, 131, 231A, 231B) to communicate with the second sensor cable (31A, 31B, 31C, 131, 231A, 231B); the method further comprising: connecting the first sensor cable (31A, 31B, 31C, 131, 231A, 231B) to a first end of a sensor cable (45A, 45B, 253) disposed on or in the electrofusion fitting (41A, 41B, 141, 241), and connecting the second sensor cable (31A, 31B, 31C, 131, 231A, 231B) to a second end of the sensor cable (45A, 45B, 253) disposed on or in the electrofusion fitting (41A, 41B, 141, 241); or routing the first sensor cable (31A, 31B, 31C, 131, 231A, 231B) across or through the electrofusion fitting (41A, 41B, 141, 241), whereby the first and second sensor cables are provided by a single continuous sensor cable. providing a first section of lined pipe (1A, 1B, 1C) with a first sensor cable (31A, 31B, 31C, 131, 231A, 231B) disposed in a continuous annulus between a first host pipe (11A, 11B, 11C, 111A, 111B, 211A, 211B) and a first pipe lining (13A, 13B, 13C, 113A, 113B, 213A, 213B); providing a second section of lined pipe (1A, 1B, 1C) with a second sensor cable (31A, 31B, 31C, 131, 231A, 231B) disposed in a continuous annulus between a second host pipe (11A, 11B, 11C, 111A, 111B, 211A, 211B) and a second pipe lining (13A, 13B, 13C, 113A, 113B, 213A, 213B); and joining the first pipe lining (13A, 13B, 13C, 113A, 113B, 213A, 213B) to the second pipe lining (13A, 13B, 13C, 113A, 113B, 213A, 213B) using an electrofusion fitting (41A, 41B, 141, 241) configured to enable the first sensor cable (31A, 31B, 31C, 131, 231A, 231B) to communicate with the second sensor cable (31A, 31B, 31C, 131, 231A, 231B); the method further comprising: connecting the first sensor cable (31A, 31B, 31C, 131, 231A, 231B) to a first end of a sensor cable (45A, 45B, 253) disposed on or in the electrofusion fitting (41A, 41B, 141, 241), and connecting the second sensor cable (31A, 31B, 31C, 131, 231A, 231B) to a second end of the sensor cable (45A, 45B, 253) disposed on or in the electrofusion fitting (41A, 41B, 141, 241); or routing the first sensor cable (31A, 31B, 31C, 131, 231A, 231B) across or through the electrofusion fitting (41A, 41B, 141, 241), whereby the first and second sensor cables are provided by a single continuous sensor cable. connecting the first sensor cable (31A, 31B, 31C, 131, 231A, 231B) to a first end of a sensor cable (45A, 45B, 253) disposed on or in the electrofusion fitting (41A, 41B, 141, 241), and connecting the second sensor cable (31A, 31B, 31C, 131, 231A, 231B) to a second end of the sensor cable (45A, 45B, 253) disposed on or in the electrofusion fitting (41A, 41B, 141, 241); or routing the first sensor cable (31A, 31B, 31C, 131, 231A, 231B) across or through the electrofusion fitting (41A, 41B, 141, 241), whereby the first and second sensor cables are provided by a single continuous sensor cable.