The diversionary route runs from Southampton to Basingstoke via Romsey and Andover, in addition to the Eastleigh to Romsey line. The works require 17 bridges to be knocked down and rebuilt; the track to be altered at 11 locations and station canopies at Andover, Romsey and Whitchurch to be adjusted. Two redundant bridges will be demolished without being replaced and three further bridges will be modified without having to rebuild them.

Richard O’Brien, Network Rail’s route managing director for Wessex, said: “It is important that the food, clothing, electronics and other consumer goods which arrive into Southampton in containers can make their onward journeys by rail at all times to stock shops around the country.

“Following the recent upgrade of the mainline, we expect increasing amounts of these goods to be shipped in larger, modern containers as this keeps thousands of lorries off the roads, and is the quickest, greenest and most efficient way of transporting them around the country. It is vital we provide an alternative route out of the port for those occasions when we carry out improvement works to the main line so we can offer a reliable service for businesses around Britain”.

Eight of the 17 bridges being knocked down and rebuilt carry public highways across the railway. The remaining structures are on private roads, or public bridleways or footpaths. The first pieces of work are due to start in August 2011 and the whole project is scheduled for completion by June 2013.

Plans are being finalised for each of the 31 individual upgrades required and specific details will be communicated to members of the public and private land owners in advance. There will also be some disruption to train services while track works are carried out, old structures are demolished and new structures lifted into place.

On 4 April 2011, Network Rail announced the successful completion of the upgrade to the mainline from Southampton to the West Midlands which will allow the modern, larger containers preferred by many global shipping firms to be transported more efficiently by train. Upgrading both rail routes out of Southampton allows freight trains to move goods, including food, clothing, electronics and other consumer products, around Britain in a quicker, cheaper, greener and more practical way.

It is estimated that the upgrade will remove up to 50,000 container lorries a year from the roads, easing traffic jams and helping reduce the billions of pounds road congestion costs the economy annually. The project was delivered more than £11.5m under the original £71m budget.