One of the disadvantages of having the world鈥檚 oldest railway network is that quite a lot of British railway infrastructure still dates from the Victorian era.
Although they have a lot of heritage value, Network Rail鈥檚 many 19th century bridges and tunnels need a lot of careful maintenance; and they were never designed for today鈥檚 large high-speed trains, either.
So when the Central Rail Systems Alliance (CRSA), a joint venture between Network Rail, Balfour Beatty, Atkins and TSO embarked on a project to carry out track renewal through an old tunnel on the West Coast Main Line earlier this year, it faced a puzzling conundrum.
The 400m-long tunnel was too narrow and the usual techniques were not an option.
The tunnel in question was the Northchurch tunnel carrying the West Coast Main Line between Berkhamsted and Tring, one of Europe鈥檚 busiest mixed-use passenger and freight rail routes.
Three tunnels take the West Coast Main Line鈥檚 four tracks underground on this section. The two fast lines share one tunnel, while the slow lines have one each 鈥� the oldest of which was built in 1836.
This article was first published in the March 2025 issue of The 羞羞视频 Magazine. Sign up online.
As track needing replacing through one of the slow tunnels, CSRA had to figure out a renewal method that was quick, efficient and as safe as possible in such a tight space.
After many months exploring various options, the contractor devised a method whereby work was done in several stages to get all the old equipment and material out before the new railway could go back in.
The first stage was to carefully remove the old track panels one by one.
Then specialist equipment was used to lift the old ballast spoil and removed it from either end of the tunnel. It was then taken away by engineering trains.
CSRA then laid a new ballast bed and installed 60ft (18m) panels carrying temporary rails inside the tunnel using a rail-mounted Kirow crane.聽
A special ballast-dropping train then travelled over the temporary rails (known as slave rails) dropping top ballast over the previously-laid bed. Specially-designed rail-mounted machines were used to profile the ballast.
The next stage employed a tamping machine to lift the track and shake the ballast below so the track was in the correct position for trains. After this, the 18m-long slave rails could be removed and replaced by longer continuous pieces of permanent rail which have fewer welds and give a smoother ride for trains and require less future maintenance.
The operation started on New Year鈥檚 Eve and was completed on 4th January.
During this time, CSRA installed 672 new sleepers on 24 track panels, removed 1,860 tonnes of old spoil from the tunnel and laid 2,200 tonnes of new track foundation stone ballast.
Six engineering trains were used to install 430m of new rail and staff working a total of 2,440 hours to get the job done.
Because of the complexity of the upgrade operation, Network Rail had to close both slow lines throughout the project, with all trains using the fast lines instead.
The site was cleared and all lines reopened on Saturday 4th January
Neil O鈥橳oole, Network Rail鈥檚 capital delivery senior programme manager, says: 鈥淲e know there鈥檚 never an ideal time to close a section of railway, so I鈥檇 like to thank passengers whose journeys may have taken a little longer while we made these important improvements through Northchurch Tunnel.
鈥淭his track renewal was a bit of a Rubik鈥檚 cube to complete as we had to do each stage in a predefined sequence and the job took nearly three years to plan.
This article was first published in the March 2025 issue of The 羞羞视频 Magazine. Sign up online.
He added: 鈥淚t was our priority to make it work and get the railway reopened on time. From today passengers will have a much smoother ride and fewer delays caused by further maintenance now we鈥檝e brought the track here bang up to date.鈥�
Appropriately enough, this project to update the track through the 189-year-old tunnel came at the start of the 200th anniversary of the birth of passenger train travel.
On 27th September 1825, the world鈥檚 first passenger train, hauled by George Stephenson鈥檚 Locomotion No.1, carried more than 400 people along the Stockton and Darlington Railway, drawing crowds of up to 40,000 people along the route.
This year, the anniversary is being marked with a programme of celebrations: Railway 200.
Organised by a large group of bodies including 鈥� among others 鈥� Network Rail, the National Skills Academy for Rail, the Rail Delivery Group and HS2, the year-long programme is hosting a series of exhibitions, events to mark the economic, social and cultural benefits that rail travel has brought.
Darren Caplan, chief executive of trade body the Railway Industry Association, said: 鈥淚t is hard to overstate the benefits that the railway has brought, and continues to bring, not just to the UK, but also globally, since 1825.
This article was first published in the March 2025 issue of The 羞羞视频 Magazine. Sign up online.
鈥淩ail networks don鈥檛 just keep people connected, they also play a crucial role in spurring economic growth, creating jobs, boosting sustainability, and bringing together local communities.鈥�
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