Improve Track Monitoring Efficiency for London Underground
In this particularly challenging project, STEMMER IMAGING has developed a sophisticated automated track monitoring system for London Underground Limited (LUL). The robust assemblies mounted on the passenger trains inspect the rail network efficiently and reliably on standard trains during normal timetable periods. Additional inspection runs during closure periods are no longer necessary, leaving the possibility of longer opening hours and more efficient track maintenance, saving money.
The task
Develop an automated track monitoring system for the London Underground network using regular passenger trains.
The challenge
The inspection runs were done during normal timetable periods in order to make maximum use of the underground's 4-hour night closure period for maintenance work. In addition, the track monitoring system to perform reliably even under the harsh environmental conditions in the tunnels.
The solution
STEMMER IMAGING developed an automated track monitoring system which can be mounted directly on the passenger trains, and which is robust enough to allow rail inspection during normal operation even at high speeds. Separate inspection runs are no longer necessary, and the closure periods can now be fully used for maintenance work.
Dirt, shocks and high speeds
The London Underground is one of the largest underground railways in the world and has more than 1,000 kilometres of track. The effort required for inspection and maintenance is enormous, which is why London Underground Limited (LUL) wanted to shift inspection from a manual process to automated recording from equipped standard passenger trains operating in normal timetable periods – in order to be able to use the 4-hour night closure period for maintenance only and extend operating times during the weekend.
The track monitoring system had to fit on standard rolling stock so it could be used during the underground's busy timetable – and be able to withstand the dirt in the tunnels as well as reliably cope with high speeds, rapid changes of direction, high G shocks and significant electromagnetic pulses caused by electrical supply being delivered via a third power rail.
„It was clear to us that track monitoring during normal timetable periods requires data acquisition on regular passenger trains, meaning that the inspection system has to cope with the challenges of moving trains – in other words, high speeds, shaking, direction changes, lots of hard shocks and all in the dark – these are extremely high demands for a vision system."
Customised solution: Fully automated track monitoring during operation
STEMMER IMAGING has worked closely with London Underground to develop a customised fully automated track monitoring system. For this purpose, high-performance and particularly robust imaging components were combined to form a compact assembly that can be installed on any train of the London Underground.
The system has been optimised for the harsh conditions in the underground tunnels and provides reliable track monitoring during the passenger trains’ normal working hours, leaving more time for maintenance work during the 4-hour night closure period.
Specialist camera enclosures for maximum protection
Specialist camera enclosures capable of operating in the harsh environmental conditions were developed with one type mounted on the bogey to provide information on the wheel-rail interface and the other mounted at the end of the carriage to provide a 4’ view of the running rails and conductor rails. The enclosures are electrically isolated to protect from EMP spikes and certified to IP65. The sub-assemblies are shock rated to 5G for continuous load (shaking) and 50G for drop.
Perfect results thanks to powerful imaging components
When selecting the vision components best suited to the harsh environmental conditions, the experts at STEMMER IMAGING could draw on their many years of experience and an extensive product range without supplier lock-in.
Each camera enclosure contains a high speed Genie camera from Teledyne DALSA equipped with IR filter and capable of operating at 120 fps, an LED IR illumination source operating at 840 nm with integrated controller from Gardasoft, together with fibre optic triggering, and a power management and conditioning system.
The solution’s key success factors
High-speed pulsed illumination
By using high speed (40 µs) pulsed illumination, the relative movement between the cameras on the train and the track is eliminated ensuring high-quality images are acquired.
Analysis via Wi-Fi
Image data is collected during the passenger trains’ normal working hours and uploaded by Wi-Fi for analysis at night. This means that no additional time is required for data collection.
Versatile infrared lighting
As parts of the rail network are above ground, infrared lighting was used that reliably avoids interference from ambient light and cannot cause problems for people due to ultra-fast pulsed light.
„This was a challenging project where we were able to utilise our considerable experience in industrial imaging to ensure that the many critical requirements were achieved at the same time.
The use of very short IR light pulses with sufficient intensity to produce good images required extremely accurate lighting control. Naturally the camera enclosures underwent rigorous testing to ensure that they met all of the LUL safety certifications.“
Other successful projects from the packaging industry
Reliable distinction between 2,500 tray variants
Together with vision experts and the Common Vision Blox (CVB) imaging library from STEMMER IMAGING, Matrium has developed an automated sorting system for up to 2,500 different types of trays. The trays for electronic components can be distinguished with the help of a machine vision system and then placed in the allotted compartments by a robot.
Benefit from our expertise in surface inspection
Turn our many years of experience into your competitive advantage. The STEMMER IMAGING experts will be happy to show you the potential of machine vision for track monitoring and other applications in the field of traffic & transportation. Get to know our solutions and services in a non-binding consultation. We look forward to hearing from you.
