BIDS TO build the £180M, privately financed second Tyne tunnel are expected to be invited this autumn after the project won formal planning approval last month.
Transport Secretary Alistair Darling's decision to give the project the green light is open to legal challenge until the beginning of October.
Tyne & Wear Passenger Transport Authority expects to invite tenders for the design, build, finance and operate project shortly after that date.
Four possible bidders have already expressed interest in the project. Balfour Beatty, Laing O'Rourke, and Bouygues each lead a team. The fourth comprises Mowlem, Nuttall and Vinci.
Construction of the 2.6km twolane crossing is not expected to start until early 2007. The central 360m section will be an immersed tube, linked to cut and cover approach tunnels on each bank.
A dry dock for the construction of the immersed tube sections would probably be built nearby at Howdon Basin.
The tunnel cross-section design features a single cell housing road traffic and an escape corridor. It is not clear whether a sprinkler system to control vehicle fires would be installed.
When the tunnel opens in 2010 it will relieve pressure on the two-lane Tyne Tunnel which takes the busy A19 under the river east of Newcastle-upon-Tyne. About 34,000 vehicles use the tunnel every day, well above its 25,000 a day design capacity.