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Process of elimination

Slotting a new route into an existing infrastructure requires ingenuity and careful planning

Italy's love affair with the car shows no sign of abating. Combine this commitment with medieval cities, packed with important historic buildings and the result is major traffic congestion.

In Genoa, the birthplace of Christopher Columbus and Italy's busiest port, the problem is further compounded by the harbour - the point from which the city expanded outwards to be bounded at the rear by the Appenine mountains.

Genoa boasts the slowest average traffic speed in the whole of Italy, with traffic running east west worst affected, its principal route being an overused elevated road which runs round the periphery of the inner harbour.

The Commune di Genova was under no illusions that something had to be done especially given the desire to expand tourism in the city, and in 1999 an international competitive tender was launched for consultants to examine possible routes. The winning consortium was a joint venture of High-Point Rendel, Symonds and local firm Aiati.

The choice could hardly have been more historically appropriate.

In March 1853, accompanied by assistant William Pole, James Rendel travelled to Genoa to discuss the scheme to move the existing naval base from Genoa to La Spezia.

Rendel met government officials and inspected the port. He found the systems archaic - it took 38 days to carry out an operation which in a comparable English facility would have been completed in just one.

In August the following year Rendel returned to Genoa with proposals for the modernisation of the port. He also submitted plans for the naval base which resulted in a complete, state of the art facility.

Nowadays, Genoa's inner harbour accommodates ferries and cruise liners rather than cargo traffic, important to the economy of the city. Another factor for the consultant to consider is the local airport located on the waterfront, well within the boundaries of the city area.

High-Point Rendel and its partners were awarded the contract late in 1999 and began assembling traffic data and modelling flows early this year. Essentially the eight routes to be appraised involve crossing the harbour either by bridge or immersed tube tunnel, or taking through traffic out of the city via a high or low level tunnel through the Appenines .

Cost would obviously be a major factor in these last two solutions. A low level tunnel would involve fewer junctions, but could be used only by drivers passing through the city. A high level tunnel, although more expensive, could accommodate junctions to take traffic to residential areas in the mountains.

There were six options for the cross harbour route. Economics were a major constraint, but any bridge had to offer 75m of clearance to accommodate shipping in the inner harbour, while tower height could not interfere with the approach to the airport. And a crossharbour tunnel route must not interfere with shipping movement.

The report presented to the Commune in April opted for the two innermost routes across the harbour as being the most viable; a suspension bridge with a main span of 610m and towers 118m above water level, or an 1.4km long immersed tube tunnel.

These proposals were accepted and the group is now working on the detail and most importantly the buildability of either solution, prior to the final decision being taken. A casting site for tunnel elements has been identified and should the bridge be the preferred solution, there are good fabrication facilities for the steel deck in the region.

Additionally, the partners were asked to work up a proposal for a high level inland tunnel route.

Planned development of major junctions either side of the harbour has to be taken into consideration, as well as future developments in and around the port.

The report was ready for presentation in mid-July and team leader Abdul Farooq of High-Point anticipates a decision after the summer recess. The aim is to provide solutions which will serve the city as well, and for as long, as those James Rendel offered 150 years previously.

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