Optical sensors improve railway safety

Sep 30, 2013

A string of fiber-optic sensors running along a 36-km stretch of high-speed commuter railroad lines connecting Hong Kong to mainland China has taken more than 10 million measurements over the past few years in a demonstration that the system can help safeguard commuter trains and freight cars against accidents. Attuned to the contact between trains and tracks, the sensors can detect potential problems like excessive vibrations, mechanical defects or speed and temperature anomalies. The system is wired to warn train operators immediately of such problems so that they can avoid derailments or other accidents, said Hwa-yaw Tam of the Hong Kong Polytechnic University, who will describe the technology and its test run next week at The Optical Society's (OSA) Annual Meeting, Frontiers in Optics (FiO) 2013, being held Oct. 6-10 in Orlando, Fla.

At least 30 times during the seven-year period, the system detected anomalous vibrations, Tam said. In a few cases, the vibrations turned out to be early warnings of dangerous emerging conditions that could have led to train wrecks. In some cases, vibration due to the use of the wrong type of lubrication oil in axle boxes was detected. The fiber-optic was designed for maintenance purposes and saves the rail company about $250,000 every year in maintenance costs.

"Using just this one type of technology, we are able to measure many things," Tam said. "This technology is perfect for systems." He added that it costs less than a third the price of other warning systems, which typically require data to be integrated from a half dozen different types of monitoring systems.

The system is now being installed in all commuter train routes in Hong Kong and will soon be rolled out in railways in parts of Singapore and Australia. With regular speeds for some of the trains in China topping out above 300 km per hour, the need for effective safety measures is profound, Tam said.

Worldwide, the rail industry is undergoing a major development boom, especially in places like China where tens of thousands of kilometers of new high-speed lines are planned for the next decade at an estimated cost of hundreds of billions of dollars.

How the System Works

The basis for the new sensor system is a technology developed in the 70s and 80s known as a Fiber Bragg grating, a type of sensor that reflects narrow spectra of light whose wavelengths shift due to temperature/strain variation. Coupling fiber Bragg gratings with another device known as mechanical transducers allows pressure, acceleration and other parameters to be measured.

The sensors are imbedded in mechanical compartments of a train or along the tracks. If there is a defect, like a sudden break in the rails or excessive vibrations because the weight of the train is off balance, those changes will alter the reflection spectra of FBGs in a detectable way.

The system is advantageous because it is all-optical, allowing the passive fiber Bragg grating sensors to monitor conditions along a train route, Tam said. It also relies exclusively on optical detection and communication, so there are no problems with electromagnetic interference from power lines that run parallel to many modern rail lines.

Explore further: Japan's maglev train runs test at over 310 mph (w/ Video)

More information: Presentation FW2I.3, "Distributed Optical Fiber Sensing Networks for Railway Monitoring," takes place Wednesday, Oct. 9 at 11:30 a.m. EDT at the Bonnet Creek Ballroom, Salon X at the Hilton Bonnet Creek in Orlando, Fla.

add to favorites email to friend print save as pdf

Related Stories

China tests 500 kilometers per hour train

Dec 27, 2011

(PhysOrg.com) -- China tested a 500 kilometers per hour (311 mph) train over the weekend. Government officials call the record-breaking speedster a “useful reference” for China’s current high ...

Japan's maglev train runs test at over 310 mph (w/ Video)

Sep 02, 2013

(Phys.org) —Moving toward its goal of building a high-speed magnetic levitation (maglev) train line between Tokyo and Osaka, Central Japan Railway Co has resumed testing of its L0 (L Zero) train—demonstrating ...

Analyzing energy potential

May 04, 2012

Sensors, radio transmitters and GPS modules all feature low power consumption. All it takes is a few milliwatts to run them. Energy from the environment - from sources such as light or vibrations - may be enough to meet these ...

India in talks to buy first bullet trains: report

Oct 03, 2012

India is in talks to buy its first bullet trains for the nation's creaking and accident-prone network, but the new fleet will run at only a fraction of its top speed, a report said on Wednesday.

Recommended for you

Lifting the brakes on fuel efficiency

Apr 18, 2014

The work of a research leader at Michigan Technological University is attracting attention from Michigan's Governor as well as automotive companies around the world. Xiaodi "Scott" Huang of Michigan Tech's ...

Large streams of data warn cars, banks and oil drillers

Apr 16, 2014

Better warning systems that alert motorists to a collision, make banks aware of the risk of losses on bad customers, and tell oil companies about potential problems with new drilling. This is the aim of AMIDST, the EU project ...

User comments : 0

More news stories

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

A homemade solar lamp for developing countries

(Phys.org) —The solar lamp developed by the start-up LEDsafari is a more effective, safer, and less expensive form of illumination than the traditional oil lamp currently used by more than one billion people ...

UAE reports 12 new cases of MERS

Health authorities in the United Arab Emirates have announced 12 new cases of infection by the MERS coronavirus, but insisted the patients would be cured within two weeks.

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...