The Vehicular tunnel is 5,500 feet long with an internal diameter of 31 feet 3 inches, and is the longest and largest diameter tunnel to be built in compressed air in Britain. It's construction involved the excavation of 180,000 cubic yards of earth and the use of 45,000 tons of cast iron primary linings, 350,000 1 1/2 inch diameter bolts and 380 tons of lead caulking. The crown of the tunnel is 50 feet below the riverbed and 90 feet below high water level in the river.

The vehicular tunnel is for use by mechanically propelled vehicles, pedal cyclists and pedestrians are excluded. It has a carriageway 24 feet wide, giving one lane 12 feet wide for traffic in each direction, and the minimum headroom at the kerb line is 16 feet. The roadway is designed to carry vehicles weighing up to 180 tons.
Ventilation stations on the north and south sides of the river equipped with fans respectively 13 feet and 16 feet in diameter and having 100 per cent reserve capacity supply up to 750,000 cubic feet of air per minute to ventilate the vehicular tunnel. Contaminated air is extracted from the tunnel and discharged at the same stations through chimneys 150 feet high.

The control and instrumentation systems for the vehicular tunnel monitor carbon dioxide, smoke density and air flow, control the intensity of the lighting at the portals, check the passage of vehicles by detectors, and give warning of vehicles which exceed the permitted height. Closed circuit television scanning the whole of the tunnel, full radio control and emergency fire points are installed, and the approach gradients are electrically heated to keep them clear of ice and snow.

All vehicles using the tunnel will pay tolls, which will be collected at the north end where four tollbooths are installed on both the entrance and the exit sides of the carriageway. There is no charge for using the pedestrian or cyclist tunnels.

The approach roads have dual carriageways, each 24 feet wide with provision for widening to 36 feet. They extend for a total of three miles from the Newcastle-Tynemouth Coast Road A1058 in the north to the Gateshead-Sunderland Trunk Road A184 in the south, and extensions already under construction or projected will connect to the Great North Road A1 north of Seaton Burn in Northumberland, to the Furham Motorway A1 (M) east of Birtley in Durham, and to the A19 and Teesside via the Sunderland By-pass. Associated works involved the construction of three railway under bridges with spans of from 120 to 130 feet, three road bridges, a diversion and a viaduct for the Jarrow light railway, and a diversion of and two bridges over the River Don.
The pedestrian and cyclist tunnels cost £900,000, 75 per cent of which was met by a grant from the Ministry of Transport. The balance of £225,000 was borne by the Durham and Northumberland County Councils in equal shares.

The vehicular tunnel with it's finishing’s, services, ventilation and toll collection equipment, and administration buildings cost £8,500,000 while the approach and associated road works cost £4,000,000. Towards this total of £12,500,000 the Ministry of Transport made a grant of £3,000,000 and the two County Councils each contributed £500,000. The balance of £8,500,000 has been borrowed by the County Councils, 75 per cent of it from the Ministry, and the loans will be repaid out of the revenue from tolls.