The Mersey Tunnels are marvels of engineering and probably the most important three and half miles of road in the Liverpool City Region. But keeping them safe and clean – and people on both sides of the river connected – is a mammoth task and one that happens while most people are asleep.

27 million journeys are made using the Queensway (Birkenhead) and Kingsway (Wallasey) Tunnel every year and keeping them running involves constant maintenance. A behind-the-scenes video released by the Liverpool City Region Combined Authority shows just how much work goes into maintaining these vital links.

Every three weeks one of the tunnels is temporarily closed during the night to allow for repairs and cleaning, using machinery built especially for the job including a scissor lift vehicle to access tunnel ceilings and a unique wall washing machine which can be hooked up to a truck.

A team of 120 people working in shifts are responsible for the upkeep of both tunnels. The experienced staff undertake a whole host of jobs from road resurfacing to repairing and replacing the thousands of lights installed across both tunnels.

The new film also reveals some rarely seen parts of the tunnels including the Queensway tunnel refuges. The fire and flood safe areas, which contain communications links and toilets, were built in 2002 to provide shelter for motorists in the event of a major incident and give the tunnels one of the highest safety ratings in Europe.

Fast facts about the Mersey Tunnels and their maintenance:

• The Kingsway Tunnel features 1,628 LED light fittings, while there are over 5,834 Fluorescent tubes in the Queensway
• Kingsway Tunnel has 16 main shaft fans, 8 fresh air blowers and 8 exhaust fans located in two ventilation stations either side of the river. These are supplemented by 32 jet fans across both tubes.
• In the Queensway Tunnel, there are 32 fans across 6 ventilation stations
• The original fans in the Queensway Tunnel are over 8m (26ft) in diameter
• Bespoke machinery is used in both tunnels, including a wall washing machine, scissor lift vehicle, gulley cleaning wagon, road sweeping wagon and a cherry picker access vehicle
• All of the Queensway Tunnel ventilation building are Grade 2 listed – the same classification as the Cunard and Port of Liverpool Buildings, two of the three graces on Liverpool’s waterfront.

Cllr Liam Robinson, Transport portfolio holder for the Liverpool City Region Combined Authority said:

“The Mersey Tunnels are some of the most important assets in the whole Liverpool City Region, providing an essential link for communities across the river as well as the many visitors we welcome to the area.

“That’s why a continuous regime of repairs and upgrades is so important to keep the tunnels up and running and safe for everyone who uses them. It’s a complex and expensive process, most of which happens late at night to make sure there’s minimal disruption for people crossing the river.

“Most of us in the City Region use the tunnels many times a year – and a good number of people almost every single day – and the reason we can do this is because of the work our fantastic, dedicated tunnels maintenance staff undertake 24 hours a day, 365 days a year.”