Cable work is under way on bridge

The preservation project is set to cost £27m

The first phase of work on the M48 Severn Bridge to combat corrosion in its suspension cables is complete.

A dehumidification system has been fitted into the centre of the main suspension cables to help repair the damage.

The work is part of a £27m project to preserve the bridge.

The humidifier works by blowing dry air into the cables to reduce humidity, dry out the wires inside and slow down the rate of corrosion.

The next phase is to install this system into all the cables, which should be completed by the beginning of 2009.

When it was opened 41 years ago, the Severn Bridge replaced the ferry service crossing from Aust to Beachley.

The new Second Severn Crossing, around 5km downstream, was opened on 5 June 1996.