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Back to basics The water industry has been a motivating force behind one of the 20th century's most significant engineering feats - taking the backache out of manhole cover lifting.

Network controllers from North West Water have been playing guinea- pig in the laboratory as part of pioneering research initiated by access cover manufacturer Brickhouse into the biomechanical impact of lifting access covers.

Under the scrutiny of ergonomic experts at Salford University's movement analysis laboratory, they have been lifting and removing access covers to assess the comparative risks of handling different cover systems.

Clad in Lycra and festooned like Christmas trees with luminous reflective markers to track the dynamic motion of joints in their legs and lower back, it is a scene which might raise a smile. But don't be mistaken.

Preventing back injury in the water industry - where employees are lifting apparatus into and out of excavations and removing heavy covers - is a very serious business.

HSE statistics show that around 40% of all reportable accidents result from injury to the trunk or back.

Regulations stipulate that the maximum lift effort required in manual handling tasks should be no more than 25kg per person.

While adopting this guideline, many water companies and authorities ask manufacturers to demonstrate additional safety features and benefits in their cover mechanisms. But there is a lack of information quantifying the true physical impact of cover lifting and how different designs disdavantage or benefit the user.

John Webb, NWW technical manager, says: 'When North West Water embarked on a major review of its cover procurement policy two years ago, we needed more hard and fast facts on cover lifting to make further progress in risk minimisation. So we were keen to participate in Brickhouse's research programme, the results of which dramatically altered certain conceptions we had.'

Two distinct cover designs were assessed. One was a traditional D400 double triangular cover requiring two-person operation (in this case the Dreadnought from the Brickhouse range). The other is a new concept, the D400 Tri-Glide, developed by Brickhouse for reduced effort one-person removal using a patented slide-out runner mechanism.

Comparative data was collected on the loading imposed on the most vulnerable area of the lower back, the joint of the fifth lumbar vertebra and first sacral vertebra.

Results suggest that compressive and torsional forces - which potentially can wreak the most damage to the lower back - are significantly less with Tri-Glide.

The lifting action for Tri-Glide is also more symmetrical compared to the traditional cover, and eliminates rotation of the spine, it is claimed. Spinal rotation is known to be an extra risk factor for lower back injuries.

Brickhouse has now embarked on further research with Salford University to develop an ergonomic lifting key.

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