STEEL rods reinforcing the concrete viaduct at Upton-upon-Severn have corroded away in places to a fraction of their original thickness.

Their condition came to light during a routine inspection in March, when high-pressure jets trained on cracks in the concrete caused lumps to drop out, exposing the corrosion.

Network control manager Jon Fraser and bridge engineer Julian Browne revealed the extent of the problem this week.

Underneath the 30 arches of the 557ft viaduct, areas last patched up in 1991 can be seen, along with extensive new patches of corrosion, where some of the exposed rods resemble well-chewed apple cores.

Small areas have also been excavated from the road surface, showing a similar pattern of deterioration in the network of steel.

"There is no alternative but to demolish and replace the whole viaduct, but we are hoping to minimise the disruption as far as possible," said Mr Fraser.

As soon as the extent of the corrosion became clear, a weight restriction of three tonnes was imposed on this section of the A4104, which links Upton Bridge with the east of the River Severn.

The road was also narrowed to prevent large vehicles from gaining access and traffic lights were installed to regulate the single-line traffic.

In the meantime, engineers have been working on plans for a new viaduct and a temporary road to keep traffic flowing during the demolition and replacement of the old one.

A planning application for a temporary diversion, taking two-way traffic to the south of the viaduct, has been submitted to Malvern Hills District Council for consideration on June 16.

Of the two suggested routes, the preferred one keeps traffic away from houses, but runs through a caravan site, which will have to be moved to the north of the viaduct.

If the plan is approved, work on Monday, June 21 and it should be complete by July or August.

Tenders for the demolition of the viaduct have to be made to Worcestershire County Council by Friday, June 4, but work will not begin until after the town's Jazz Festival, which will bring hundreds of visitors to the town from June 25 to 27.

It is hoped to complete major structural work by September, before any floods and to complete the new viaduct by spring next year.