MechChem Africa July 2018

⎪ Automation, process control and instrumentation ⎪

Scanner technology protects world’s longest railway tunnel

A laser scanner solution from SICKAutomation is now protecting the overhead line through the 57 kmGotthard Base railway tunnel, the longest in the world.

A fter 17 years of construction, the Gotthard Base Tunnel (GBT) finally opened to passenger and cargotrafficon11December2016. Deployed as a sensor solution for protection of the overhead line, LMS511PRO laser scan- ners fromSICKhelpensure that the trains op- erate on schedule through the 57 km tunnel. The scanners are incorporated into techni- cal monitoring systems to protect the electri- cal section breaks along the overhead line in the GBT. “To ensure continuity of normal rail service, sections of the overhead linemust be isolated from the grid for maintenance and in the event of an incident,” explains Patrick Hayoz, electrical engineer and project man- ager for System Design Traction Current in the infrastructure department of SBB, the Swiss National Railway. Additional requirements apply in relation to tunnel capacity – up to 260 passenger and cargo trains onpeakdays –aswell as the short train headways. “To ensure high availability of the infrastructure, all fault risks should be eliminated, whenever possible,” adds Hayoz. The GBT is constructed for speeds of up to 250 km/h, which result in correspond- ingly high wind speeds and pressures of up to 10 kPa. Accordingly, the overhead line is constructed to sufficiently durable standards over its entire length: more than 100 km. Aside from the maximum train speeds, however, potential effects of an unscheduled stop in the tunnel also had to be considered. “In electrical section breaks, two contact wires extend in parallel for almost 20 m. If a pantograph remains stationary in such a position, the current through the connecting wires can cause overheating at the contact point,” says Hayoz. “In turn, this can cause the contact wire to break, which usually means a track closure of several hours.” Togetherwith a committeeof subjectmat- ter experts, he tested andvalidated a series of riskminimisation solutions toprevent contact wire breakage. Of these, pantograph detec- tion using LMS511PRO laser scanners from SICK proved to be the ideal solution – based on technical- and cost-effectiveness and time considerations. Suitable for outdoor use, the LMS511PRO laser scanner fromSICK is a 2Ddetecting and

measuring sensor with a scanning angle of 190° and an operating range of up to 80 m that offers adjustable angular resolu- tion of between 0.167° and1.0°. “The systemmea- sures the pulse travel time of a pulsed laser beam to an object – in this ap- plication, the pantograph – and the remission time from the object surface,” explains Mark Madeley, national product manager for Identification, Vision, Distance and Ranging at SICK Automation Southern Africa. Along with adaptable software

filter algorithms, the laser scanner’s 5-echo evaluation technology ensures ex- tremely dependable return pulse detection; it therefore produces highly reliable data regarding thepresence, distance andposition of the pantograph. “In the case of a stationary pantograph in an electrical sectionbreak, this data is used to initiate a changeover of the overhead line supply. The changeover process has to be completed in a maximum of twenty seconds to exclude the risk of spot overheat- ing,” adds Hayoz. The LMS511PRO is an industry-tested, rapidly deliverable standard system that has proven itself in a range of different applica- tions. Its open interface concept offers maxi- mum connectivity. Fresh from the factory, it therefore met significant SBB requirements determined by project progress at that time, tunnel useallocation for test-drives, aswell as the approaching commissioning date. The LMS511PRO underwent technical validation at the SBB depot in Bern – and passed with flying colours. “The decisive features were its detection reliability, low installation outlay, connection to external systems, as well as the remote control and configuration capabilities,” says Hayoz. All LMS511PRO units in the GBT are mounted on a specially developed support console adapted to the radii of the tunnel walls, whichprotect the sensor alongwith the electrical connectivity from airborne small

SICK LMS511PRO laser scanners are protecting the overhead lines through the 57 km Swiss Gotthard Base railway tunnel. parts aswell asmisalignment due tohighwind loads. Theunits aremountedoverhead, which both simplifies cabling and enables the status indicatortobereadfromtheground.Inopera- tion the laser scanner works in ‘tunnel view’: it is oriented to view only the pantograph, preventingitfrombeingdistractedbyanother travelling train. “To ensure maximum availability even in the harsh everyday working environment, a remote access capability was set up to allow SBB access to the laser scanners via theGSM network,” says Madeley. “This makes it pos- sible to monitor the systems for contamina- tion or misalignment, analyse functions and measuring data during operation and even subsequently adjust individual parameters through software, despite the difficult access situation within the tunnel.” TheGotthardBaseTunnel is sure tobeone of the century’smost prominent construction projects, setting the standard for an age, with its plethoraof highly advanced safetydevices. “At SICK, we’re glad we could do our part to contribute a small yet sophisticated solu- tion for protection of the overhead line and thereforehelpensuretherequiredavailability of the new north-south rail axis through the Alps,” concludes Madeley. q

July 2018 • MechChem Africa ¦ 31