3-D Laser Scanner Keeps Trains Safe

An infrared 3-D laser scanner that mounts on trains or cars can detects obstacles and unsafe conditions on the track or road.

A team led by Heinrich Höfler and Harald Wölfelschneider of Fraunhofer Institute for Physical Measurement Techniques (Fraunhofer IPM) has developed a technique that uses rapid infrared laser pulses to create an extremely fast, highly precise 3-D laser scanner that is eye-safe for humans.

The scanner sends out 1 million laser pulses per second and determines how long it takes for the beam to be reflected back. The time in between pulses is very short, creating a slow-motion effect that makes it easier to measure the light's reflection.

Dr. Heinrich Höfler and Dipl.-Ing. Harald Wölfelschneider, left to right, with a 3-D laser scanner that improves safety and reliability on railroad tracks worldwide. (Image: © Dirk Mahler/Fraunhofer)

Developed with railway safety in mind, the researchers mounted the device on a train to spatially measure the position of the rail or contact line relative to the train. These details will be useful for identifying obstacles in the track or determining the best course for a load-bearing train.

“For Deutsche Bundesbahn (German Railway), we equipped a measurement train that scans the surroundings of the test track, using several laser beams and which delivers — taking 4 million measurements per second — a 3-D image of what it scans,” Wölfelschneider said.

The scanner also can be held stationary to observe passing trains. Taking imaging data on the train itself can show if its cargo has slipped into a dangerous position. The device also could be mounted onto a car that lets the scanner find small obstacles, such as lane grooves, potholes or changes in height in the road, to a difference of just 0.2 mm, even while traveling at speeds of up to 50 mph. It is the first scanner approved by the Federal Highway Research Institute for this purpose.

The scanner is already a commercial success and has been implemented to improve rail safety worldwide. Höfler and Wölfelschneider will receive one of the 2012 Joseph von Fraunhofer awards for their work.

See also: FBG sensors monitor high-speed rail system

For more information, visit: www.fraunhofer.de/en