Client: Hewlett Civil Engineering
Type of works: supplied a 3m high Reflective Acoustic Barrier.

The contract was carried out for Hewlett Civil Engineering and the designed brief given to the Betta Group was for a 3m high reflective acoustic barrier positioned on top of an exposed earth bund, with a noise attenuation of 25dB(A), all within a tight financial restraint.

Hewlett Civil Engineering designed the post foundations to the overturning moment of the barrier and post centres calculated by the Betta Group. The concrete foundations were brought to within 450mm of the top of the bund, allowing the post/base plate gussets to be completely below the soil level. The standard Betta reflective acoustic barrier has a noise attenuation of 20dB(A) and the company redesigned the barrier to comply with the design brief of 25dB(A).

The galvanised universal beam posts were set at 3m centres and fixed to the concrete foundations with chemical anchors. The timber used was softwood from a renewable source, pressure treated with Green Tanalith E. The barrier was designed to follow the curves and contours of the bund without stepping.

The wet summer of 2007 caused considerable installation difficulties and at one point the whole site was abandoned through the sheer volume of water. The photographs show how the heavy rain deposited substantial excavated material onto the surface of the concrete foundations, making the clean off and grouting extremely difficult. In some cases the clean off had to be done twice.

The two companies co-operated well together and in spite of a very exposed and wet site, the progress on the barrier was good and the difficulties overcome.