I never realised how protracted and complex the litigation would be when I was approached by a contractor to support them as an expert witness in securing payment for a massive installation they had done for a so-called 'smart bridge'. The client felt the bridge wasn't smart enough (and was susceptible to undetectable dangerous conditions such as high winds).

Smart bridges (including other smart structures) are where all the different areas in engineering neatly converge – mechanical, electrical, electronics, instrumentation, chemical and civil engineering. Sensors in the structure identify potentially catastrophic structural problems and warn of incipient dangerous conditions. You may remember the spate of recent bridge failures. For example, the 8-lane steel truss-arch bridge across the Mississippi River in Minneapolis collapsed during the evening peak traffic flow time with 13 people killed and 145 injured. The central span suddenly gave way after the gusset plates connecting the steel beams suddenly fractured. The replacement bridge has strain and displacement gauges, accelerometers, potentiometers and corrosion sensors to detect corroded concrete and strained joints (costing less than 1% of the overall cost).

Building smart structures and bridges now represent a strongly growing business in engineering. The bridge spanning the Gulf of Corinth in Greece, has over 300 sensors alerting its operators to earthquakes and high winds so that it can safely be shut down.

Wireless is the way to go
The new generation of sensors are based around wireless and new energy efficient and innovative technologies. Such as cement-based sensing skins which can detect strain changes on structures. This gets round the problem with cracks appearing between sensors with problems which then get missed. Another clever strategy is to put sensors on vehicles that regularly cross bridges and monitor resultant changes.

The challenge is in the data
One of the challenges with sensors is the huge amount of data generated by these sensors and the need to efficiently mine the data to obtain trends and useful warnings well in advance.

How can you take advantage of this?
Tiny sensors – low cost, self powered and wireless-based are moving into everything we do. Take advantage of them in your next civil or mechanical engineering project to offer an additional service to your client on the health of the structure.

With the masses of money poised to be spent by national governments on our rusting and rotting infrastructure – roads; rail and bridges are poised to be flooded with sensors. And at a typical 1% cost for sensors (of a huge amount of money in building all this infrastructure); this discipline is going to be a busy area of engineering.

In terms of your next engineering project, do as Jack London remarked: 'You can't wait for inspiration. You have to go after it with a club.'

Yours in engineering learning


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