Client: Bournemouth Borough Council
Duration: June 24th - June 28th
Date posted: 01-07-2013
MMC Diving Services won the tender to survey the two Iford bridges and Tuckton bridge in the Bournemouth area for Bournemouth Borough Council. With the dramatic flooding and extreme weather conditions we have experienced in recent years, under scour has been top priority for all the UK railways, highways and councils. Bridge scour is the removal of sediment such as sand and rocks from around bridge abutments or piers.
Scour, caused by swiftly moving water, can scoop out scour holes, compromising the integrity of a structure. Bridge scour is one of the three main causes of bridge failure (the others being collision and overloading). It has been estimated that 60% of all bridge failures result from scour and other hydraulic-related causes. Water normally flows faster around piers and abutments making them susceptible to local scour.
At bridge openings, contraction scour can occur when water accelerates as it flows through an opening that is narrower than the channel upstream from the bridge. Degradation scour occurs both upstream and downstream from a bridge over large areas.
Over long periods of time, this can result in lowering of the stream bed. MMC carried out a full hydrographical survey of the three structures. Bed mapping and use of HD underwater video equipment with a topside repeater for our on-site engineer determined what action was needed to repair existing scour and implement a sustainable protective system for the future.