Ever wondered what it's like behind the scenes in the Mersey tunnel? To mark today's 50th anniversary of the Kingsway Wallasey tunnel opening, the Globe was taken on a special tour.
Expertly guided by Merseytravel Senior Officer Nick Biglow, our tour starts with a testing climb up a narrow ladder onto the roof of the bridge that runs over the toll booths.
This reporter doesn't have too much of a head for heights, but once 15 meters above the road, the view is spectacular.
When first constructed, its sole purpose at the time was to house offices for key staff, the police control room and it was also a good vantage point to monitor traffic.
Safely back on the ground, a plaque to the side of the bridge marks the spot where the Queen stood to unveil the grand opening of the tunnel on June 24, 1971.
If the view above the tunnel has been far-reaching and open, things are about to get a lot darker as Nick takes me into the tunnel and down to a small entrance door that will reveal the inner workings of the whole operation.
Steps leading down underneath the tunnel road surface have a sinister feel, but that is nothing compared to what we are about to see below.
At the bottom of the stairs we can now see the curved base of the tunnel shape that was originally cut through the river bed.
Along it run a series of pipes and a murky walkway continues for as far as the eye can see.
I'm glad Nick is with us as I certainly wouldn't fancy doing this on my own.
As we make our way down this spooky tunnel, water runs below our feet.
This area underneath is called The Inverts and is designed to supply the air flow throughout the tunnel.
Fresh air is blown in from vent stations, including Promenade Vent station, which is located at Seacombe. This pushes the carbon monoxide through the tunnel to the other end at Victoria Vent Station (located near Costco in Liverpool) where the exhaust fumes are extracted.
The area also provides water, gas and electricity which feeds both Wirral and Liverpool.
Panels on the wall control the lights for the tunnels.
Next, we are heading up a ladder that leads to a tube which allows workers to get from one side of the tunnel road to the other.
I looks like something out of Star Wars or a horror movie.
A stairway then takes us back up to road level on the other side. No lift was installed in the Kingsway tunnel, but we are told that there is one in the Queensway.
Halfway through the tunnel there is a layby that only came about by chance.
Nick said: "The layby is there due to the boring/mole machine breaking down with a bearing failure at this location.
"As there was no way of accessing or getting to the machine the only way to change it was to dig out an area at the side of the machine. Hence the layby was born!"
As we head back to our starting point along the narrow walkway next to the tunnel road, maintenance teams are hard at work.
Nick says: "On average, there can be about 25 Merseytravel staff working through the night plus specialised contractors which have been organised through Merseytravel.
"The jobs consist of electrical (lights cables), mechanical (fan maintenance) and general cleaning of the tunnel, road sweeping, cleaning out the gullys and washing of the walls which is carried out by the Unimog cleaning machine."
The tour has been a fascinating one and shows just how much work goes into keeping traffic flowing from one side of the river to the other every day.
Will we still have a Kingsway Tunnel in another 50 years? Only time will tell.
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