Mega Tunnels 3 - Sapperton

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3. Sapperton Tunnel

The third place is occupied by another abandoned tunnel, this time located on the summit pound of the Thames and Severn Canal.

This 3,817yard tunnel was built 15 feet wide and 15 feet high to accommodate the Severn Trows, which were the target market for this connection between the rivers Severn and Thames.

It was completed in 1789 after five years of construction and was one year over schedule, not a bad result by tunnel building standards of the day. As so often happened, the original contractor only managed to complete one third before he hit financial problems and the remaining work passed to others. In the end the tunnel Included 25 intermediate shafts the deepest of which was 244 ft.

The Sapperton Tunnel held the record as the longest from 1789 till 1811, when it was eclipsed by the completion of the Standedge in the north.

With declining trade the tunnel was officially closed in 1910, but remained passable till 1966 when roof falls in areas passing through the unstable Fullers Earth blocked it as a through route.

Today occasional trips are made as far as the roof fall and plans are well advanced to reopen the tunnel as part of the ongoing Cotswold Canal restoration project.

All photos sourced from the internet - I am not brave enough to go inside!

Mega Canal Tunnels 2 - Higham and Strood

2. Higham and Strood Tunnel

March 2019

This is the Walter Mitty of canal tunnels, with its 3,946 yards holding the second place for a tantalisingly short period of six years.

The Higham and Strood during its short operational life

It was opened to boats in 1824, but tidal flows through the seven mile canal made passages very difficult. It was soon reduced to two shorter tunnels when a 100 yard central passing place was opened out in 1830. The result was the creation of the paired Higham and Strood tunnels, neither of which would meet my 2,000 yard qualifying criteria.

And as it is now

I suspect that this is the UK’s least known long canal tunnel, but perversely it is also probably the most travelled canal tunnel of all time. In 1845 the canal tunnel was shared with a new railway track, with one half resting on the 5ft towpath and the other side precariously supported on wooden pilings set in the water. Even in those laid back days, the railway inspectors deemed it unsafe and in 1846 the whole tunnel was sold to South Eastern Railway who filled in canal channel and laid a double track forming part of the North Kent Line. The line remains operational today and regular commuter trains rush through at up to 70mph on their way to St Pancras station.

Compare the profile of the portal to the water filled etching above

But we are jumping ahead of ourselves.

When the tunnel was built by the Thames and Medway Canal (aka the Gravesend and Rochester) it was a huge structure, 35ft high, and 21.5ft wide at the waterline plus its towpath. It was built to these generous dimensions to allow 60 ton Thames sailing barges to pass through with their masts lowered, and in doing so avoiding the rather perilous passage round the Hoo Peninsular.

A train in the opened out central section

Initially the tunnel consisted of the unlined chalk of the North Downs, but repeated rock falls resulted in the installation of brick lining, a process completed from end to end in 2005. Most falls were in the areas weakened by the six construction shafts.

As suggested by its short life as a navigable tunnel, it was never a popular or successful route. Boats were often caught between tides in the central basin and the journey down the canal often took longer than the more risky passage round the peninsular favoured by the barge skippers.

UK's longest canal tunnels 1 - Standedge

Mega Tunnels 1 - Standedge

March 2019

I recently had a two part article published in Waterways World (Feb and March 2019) under the title Super Tunnels.

The article contained a few images but not all the ones I found and I thought it would be interesting to feature a wider selection of images, along with a version of the text in a series of blog posts.

For the full article I would recommend you get a copy of the relevant months editions of the magazine in either hard or soft copy.

I will be posting a focus on the 14 tunnels which are over 2,000 yards in length starting with the mighty Standedge. Interestingly, I have very recently come across a quite amazing 30 minute YouTube vlog by Martin Zero of Manchester, in which he undertakes a perilous exploration of the two disused railway tunnels and the linked canal tunnel. The link is here:

Martin Zero : Almost the Longest & Deepest Canal & Railway Tunnels in Britain

Get a cup of tea, sit down and enjoy.

I would hasten to point out that this is not open for public access and I would not suggest anyone else tries to gain access to what is a very dangerous environment. But it does make compelling viewing!

1. Standedge Tunnel

The Standedge Tunnel on the Huddersfield Narrow Canal commands the top spot in terms of canal tunnels by just about every measure.

At 5,698 yards long, it burrows under the Pennine ridge for well over three miles and is a full mile longer than its nearest rival. Not only is it the longest but it is also the highest (643 ft above sea level) and the deepest (636 ft below the moors) and can therefore justifiably claim to be the king of the tunnels.

It was built over a period of 17 years and was finally completed by Thomas Telford in 1811, creating a direct connection between Manchester in the west and Huddersfield in the east. To fully appreciate this wonder of the waterways you really need to walk up to the Pennine Way which crosses the line of the tunnel, and from this lofty vantage point it is possible to look west to the Diggle end and then east to the hill which blocks the view to Marsden. I first climbed this hill about 10 years ago and every time I return I wonder at the audacity of the early engineers who stood on the wild moors in the 1700’s armed only with explosives, pickaxes and wheelbarrows and concluded that they could drive a navigable tunnel all the way through the stubborn Pennine rock.

To be honest, the tunnel took far longer to build than they expected and swallowed a hefty £160,000, making it also the most expensive tunnel in the country. Work progressed simultaneously from both ends and a central shaft but sadly claimed the lives of over 50 of its workers.

This was a narrow canal and navigating its massive summit tunnel was a slow business. There is no towpath and all boats had to be legged through, a trip taking 1hr 20 mins for an empty boat and up to three hours for one laden with goods. In the early years business was brisk and about 40 boats were worked through daily.

Whilst it was a narrow tunnel, two-way working was planned with passing places constructed. In practice this did not work out well and single way traffic became the norm, as it does today. The last commercial boat passed through in 1921 and it was closed to traffic in 1944, although Tom Rolt and Robert Aickman made a final and much celebrated passage in the Ailsa Craig in 1948. After being left to its own devices for over 50 years, save an occasional inspection, the tunnel was repaired and reopened for through passages in 2001 at a cost of £5m.

Today the canal tunnel is one of a set of four parallel tunnels, with the other three being railway tunnels, of which just one remains operational. The four tunnels are connected by cross adits which were used to move spoil during the construction of the railways, easing their construction.