Case Perniö

The Perniö fall test put automatic inclinometers to unimaginable conditions. Nine devices were used to monitor the ground around the test site.

The Perniö fall test put automatic inclinometers to unimaginable conditions. Nine devices were used to monitor the ground around the test site.

In October of 2009 Tampere University of Technology (TUT) and the Finnish Rail Administration conducted a full-scale railway embankment failure experiment in Salo, Finland.

A new, small railway embankment was built in place of an old, de-commissioned blind track on a clayey soil. Four steel frameworks, each 12 meters long, were used to simulate short railway cars with bogie carriages. The frameworks were loaded with modified shipping containers which were gradually filled with sand.

The test area was extensively instrumented with 40 pore pressure gauges, 9 inclinometer tubes, 2 total stations monitoring a total of 27 prisms, 9 earth pressure gauges, 3 settlement tubes and 76 slip surface measuring pipes. In addition, the weight of the containers was measured with strain gauges on the frameworks. Acceleration gauges were used to measure the tilt angle of the containers. The fall test lasted for appr. 24 hours. During this time considerable overload was loaded onto the carriages.

All devices detected movements before the actual failure of the railway structure. In normal conditions the alarm system gives an alarm immediately when movements are detected, which gives enough time to ensure safety.

After the carriages had tipped over, the horizontal movements were approx. 1000 mm. All measurement devices operated perfectly also after the large movements.

See the video filmed by Tampere University of Technology.

Source: Finnish Rail Administration