| As part of Metronet’s Technical Services Team, the AVI Section provides instrumentation and testing expertise to support the company’s overall engineering functions. One of its key roles is to undertake track and track-train interface surveys using high tech custom video equipment. These surveys are conducted throughout the year on the nine lines in the network and also include train-borne thermal imaging cameras. For this purpose, the camera is mounted on the front of a train travelling at normal line speeds. |  |
| AVI does a concurrent visual and thermographic ‘sweep’ of the track network to reveal hot-spots that are then investigated in detail by the traction supply engineers who themselves have hand-held FLIR Systems infrared cameras. Prime targets are high voltage bonds, insulators and trackside switchgear. “Thermography adds an extra dimension to our survey facilities, allowing us to look at the track supply system,” explains Metronet AVI Systems Engineer, Salim Mohamed. “Additionally we are now using the technology to survey our rolling stock.” |  |
| For inspecting the integrity of electrical and mechanical systems on the underside of trains, infrared cameras are installed under the tracks. Monitoring is carried out during service hours without any disruption to the running schedules. |
| FLIR Systems has provided all the cameras currently in use at Metronet. AVI’s work is increasingly calling for real-time thermal imaging and digital output. For these applications the company invested in three, top-of-the-range ThermaCAM® S-Series infrared cameras to supplement it’s professional P-Series models. |
| In line with all companies in this sector, Metronet’s contract is based on performance and quite simply any unnecessary service delay carries a cost penalty. Thermal imaging is part of a package of measures enabling the company to maintain the network infrastructure pro-actively and it is now seeking to develop its methods to grade the criticality of faults detected. |
| The collaboration between rolling stock, track, traction supply engineers and the AVI team is resulting in temperature thresholds being set for critical system elements, with each being assessed on its individual characteristics. |
| Service requirements are also being taken into account. “For example, we may set lower thresholds for the lines that serve central London,” Salim Mohamed explains. “Clearly more trains run on these traction circuits and there is a much higher cost implication in the event of failure.” |
| Next in line will be the development of Metronet’s datalogging system to automate the survey process further. This work will result in the digitising of its visual survey work initially. Thermal imaging will soon follow and by choosing FLIR Systems ThermaCAM® S60, Metronet already has the hardware to support this development. This model is designed to provide 50Hz digital recording and evaluation of high-speed events. Its enhanced connectivity options include an IEEE-1394 FireWire interface for real-time transfer of fully radiometric 14-bit JPEG images and associated data. |
|
Note: Working in partnership with London Underground, Metronet has taken over responsibility for upgrading, replacing and maintaining nine of the twelve lines of the entire network and will spend £17 billion during its 30-year contract. Some £7 billion of this will be spent during the first 7.5 years – on new trains, new track new signalling and refurbished and modernised stations.
|
