Linear sensors from Bestech Australia are being used to detect problems caused by expansion and contraction in railway bridges.
Engineers typically place expansion joints in bridges to counter the effects of expansion and contraction due to seasonal heating and cooling. However, when it comes to railway bridges, this problem is compounded as the expansion of a mile-long section of rail could be as much as 1.5m over a temperature change in some climates of 37.7°C, leading to rail buckling, or ‘sun kink’, and resulting in train derailments.
Advancements in steel tracks including the use of pre-stressing techniques are helping to control the effects of expansion and contraction. Many railway companies and mass transit agencies are taking the solution a step further by instrumenting the bridges themselves to find out the extent of movement of the bridge, and to determine if any structural problems exist or if any track shifting has actually taken place.
By knowing that tracks have buckled or kinked, railway companies can divert trains and repair track problems before a potential incident.
All railroad bridges in Australia are required to be inspected, but these inspections are done largely on a visual basis.
The LV-45 series linear sensors from Bestech Australia are being used to measure bridge movements. Designed to survive elements such as high humidity, blowing snow, and driving rain over a wide temperature range (-40°C to 100°C), as well as withstand the inherent shocks and vibration from a train, the Alliance Sensors LV-45 series is the ideal solution for such applications.
Featuring an IP67 rated housing, the linear sensors are offered with various connector and cable terminations to suit virtually any environment.
In a typical pier-to-bridge interface measurement application, the LV-45 sensors are hard fixed to the pier and the bridge, using ball joint swivel rod-ends to take up any misalignment during initial installation. The system can measure position changes in all three axes and track those changes over time to show short and long term trends and highlight potential problems or incipient failures before they take place.