Traffic will be halted for the diamond jubilee celebrations, but the normal daily passage of 40,000 vehicles, 60 per cent more than anticipated in 1934, represents a main artery of the Merseyside economy, the factor which removed more ships from the river than any other.
Both banks of the river flourished during the heyday of North Atlantic trade, and a large fleet of ferries shuttled back and forth, using perilous jetties to shift loads.
Passenger ferry traffic, mainly commuters from Wirral, halved when the railway pushed under the Mersey but, until the road tunnel opened, 'luggage ferries' running every 20 minutes still could not cope. The river was hopelessly congested.
'Boss' Archibald Salvidge, the great leader of Protestant working-class Toryism, pioneered the idea of a tunnel. Salvidge died before it opened, but forged the Liverpool-Birkenhead municipal partnership which persuaded Whitehall to lend the pounds 34m needed.
Work began in 1925, after completion of research by John Haldane, a mining engineer at Birmingham University, solved the problem of ventilating such a huge subterranean space.
Giant fans, still in perfect working order, push air along the bottom of the tube, and up through the road deck.
Carbon dioxide emissions, which rise thermally to the top of the tunnel, are pushed out of the tunnel by the passage of traffic.
It has long been the tunnel operators' claim that the air in mid- river is cleaner than in the city centre.
Queensway is 44ft in diameter. It took 1,700 men to displace 1.2 million tons of rock and create the tunnel with 82,000 tons of cast iron and 270,000 tons of concrete. When completed it was twice as long as any tunnel in the world, and remains the longest four-lane tunnel - a structure of bold engineering innovation typical of the railway era. The baggage ferries were wiped out.
The tunnel's finances have been a source of some concern. Traffic reached a peak of 18.2 million vehicles in 1971, when the Mersey authorities were committed to the opening of a new tunnel, the Kingsway. The Government had agreed to reschedule the debt to allow Kingsway to be constructed, but the 1973 oil crisis and recession, in conjunction with the decline of North Atlantic trading routes, depleted revenue from tolls.
The two tunnels became a pounds 110m debt burden which John Gillard, general manager and historian of the tunnels, says is now under control, with traffic volumes increasing. Cars pay pounds 1, lorries up to pounds 4.
'It is the cheapest tunnel toll per mile. Dartford charges 90p for half the length,' Mr Gillard said.
'It has also been one of the safest stretches of road,' he added. 'There have been very few incidents, although a water main burst three years ago and we had to pump out half a million gallons. The water company didn't have to pay a penny compensation.'
They had best be on their guard on Sunday, when the public will be allowed to walk through Queensway and view an exhibition at Albert Dock which will answer many enduring questions.
For example, why are there bends in the tunnel? Because it had to swerve around rail tunnels at the Birkenhead end and avoid undermining some big buildings near the Liverpool waterfront. The Liverpool Philharmonic, conducted by Carl Davis, will be in full evening dress for their midday concert, which will run an appropriate gamut from the Onedin Line theme to a Beatles medley.
'It will be a sonic experience,' Mr Davis said. The music will carry to the art deco masterpieces which form the tunnel entrances, and so will the air. Queensway is a masterpiece of its kind.