AVT has been keeping a close eye on an important road viaduct in the centre of Burnley.
Monitoring specialist AVT has been involved with the recording of long term movement of a 150m elevated section of the Centenary Way viaduct carrying the A682 dual carriageway through the centre of Burnley.
Over this relatively short section the two carriageways are supported on six concrete piers and two abutments close to residential and commercial buildings.
There are a total of 32 bridge bearings supporting the bridge deck and it was observed during routine bearing inspections that some of these showed little or no sign of movement. Normally a grease line shows the limits of movement but there was very little evidence of this, prompting the need for further investigation by LancashireCounty Council engineers.
The route taken by the A682 at this point is particularly complex with the viaduct spanning two different roads, the Liverpool Canal and several buildings.
Given the complexity of the road structure and its location, it was estimated that the cost to replace all the bearings could run into millions of pounds. Before doing this it was decided to carry out further long-term tests to discover the nature of the problems.
The key measurements in the project are temperature, strain and displacement. AVT is using four separate measuring technologies to obtain a clear and comprehensive three dimensional picture of how the viaduct and supporting structures are behaving during changing environmental and operational conditions.
Results are being obtained from both permanent solar panel powered instrumentation and portable geodetic optical monitoring equipment.
AVT has also developed remote visual and physical measurement techniques for safely monitoring cracks and loading patterns in concrete structures at nuclear power facilities.
These were used effectively during the decommissioning of the Trawsfyndd nuclear power station. AVT’s 36 channel wall monitoring system was designed to measure stresses in the concrete reactor walls and boiler box walls.