A shipping expert has described Dibden Bay as the ideal location for a new container terminal.
Mike Garratt's evidence to a public inquiry into the scheme also stressed the economic need for a deepwater port on the south coast.
Mr Garratt said a rapid rise in the number of container movements meant the industry was heading for a shortfall in UK capacity.
He warned that more goods were likely to be imported via rival ports on the continent unless the Dibden Bay scheme was approved.
"The consequences of not proceeding with the proposed Dibden Terminal are serious from the point of view of the UK economy," he said.
Mr Garratt is managing director of MDS Transmodal Ltd, a transport consultancy that specialises in the ports, shipping and freight industry.
He began his evidence to the inquiry by listing the geographical benefits of building the terminal on the site selected by Associated British Ports.
He said: "Southampton has important locational advantages. It's close to the main shipping route to the North Sea ports and has high quality road and rail connections.
"These advantages were recognised by the deep sea liner companies in the 1960s. They led to the establishment of Southampton Container Term-inal and a network of 'liner trains' which linked the port with inland container bases.
"The proposed Dibden Terminal is focused on deep sea container trades employing the largest ships likely to be operating in the foreseeable future."
Mr Garratt listed the criteria that should be adopted when selecting sites for new terminals. These included sufficient space for all necessary services, adequate depth of water for the biggest container ships and good quality road access.
"The Dibden Terminal meets these criteria," Mr Garratt told the inquiry.
"The existing channel can already accommodate the largest ships and the Strategic Rail Authority is committed to any required upgrade of railway infrastructure.
"Unlike proposals put forward for the rivers Thames and Medway, containers landed at Dibden would not have to pass through the congested London area to reach regional markets."
Mr Garratt finished giving his evidence shortly before lunchtime. The hearing was then adjourned for the rest of the day after supply problems caused by a burst main left the building without running water.
Inquiry inspector Michael Hurley said it was unfair to expect people to use a building in which they were unable to wash their hands.
The hearing was scheduled to resume today.
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