Inside the Penarth Subway beneath the River Ely

A rare colour photo showing the inside of Penarth’s pedestrian subway beneath the River Ely

An extraordinary 21st century analysis of one of Penarth’s major – but unsung – engineering triumphs,  the long-forgotten pedestrian tunnel beneath the River Ely, has now revealed  just how technically advanced the original Victorian design was.  

Computer generated scale image of what the tunnel looks like inside

Computer generated scale image of what the tunnel looks like inside. The pipes carried hydraulic power, water and gas.

The pedestrian tunnel ran from what is now Plas Pamir, beneath the River Ely to the area where Cardiff Bay Yacht Club now stands. It was a thoroughfare linking both banks of the river – allowing  pedestrians, including hundreds of sailors and dockworkers, to cross the Ely without negotiating the muddy river banks and taking the chain ferry.

The engineering exercise re-appraising the tunnel – or “Subway” as it was called – is  part of a remarkable historical website project on Penarth Dock and the Ely Tidal Harbour initiated by engineer (and former Penarthian) David Carder.

David Carder, wife Julie and son Martin - now MD of their company

David Carder, wife Julie and son Martin – now MD of their company

In 1966 Mr Carder was an apprentice at the Penarth Dock Engineering Company for which his  wife Julie also worked .

His son Martin is now MD of their firm Rota Design Ltd in Hebden Bridge West Yorkshire and is also involved in the project.

Mr Carder is determined to pull together an authoritative  history of Penarth Dock and the Ely Tidal Harbour using original plans, photographs, documents and personal recollections before they are lost in time.

He’s gleaned original detailed drawings showing the “complex geometry” of the tunnel which inclined downward to its midpoint and also curves laterally.

The route of the curving / dipping Penarth Subway

The route of the curving / dipping Penarth Subway

The father and son team have used three-dimensional CAD (computer-aided-design) technology to create a virtual model of the “subway” – as it was called.

Work started on building the original 1250ft-long cast-iron tunnel on July 5th 1897 and – despite two floods during construction – it was completed on  May 14th May 1900. Although now sealed off, it’s still in situ beneath the River Ely today .

The official opening of the Penarth Subway in 1900.

The official opening of the Penarth Subway in 1900 with all the great and good of Penarth in attendance.

Victorian pedestrians paid a penny for each crossing. Once inside they found there was 6ft 6 inches of headroom – just enough for a top hat. A string of the newfangled electric light bulbs lit their way as they walked down a steep incline (1 in 7) to a mid-point 50 feet below sea level (at Mean High Water Springs) and then climb the ascent to reach ground-level at the other side.

This profile of the tunnel shows the downward and upward slope

This profile of the tunnel shows the downward and upward slope

Any water on the walkway of the tunnel was drained away through grids to pipes beneath and pumped dry. The tunnel also carried gas pipes, water pipes and hydraulic power lines for coal-loading machinery (and later an 11,000 volt electricity cable). The man who designed it was Taff Vale railway engineer George Sibbering .

The tunnel was used  until 1936 when Penarth Docks were (temporarily) closed./ It was then re-opened for use as an air-raid shelter during the Second World War and for dock operations when Penarth Docks were taken over by the US Navy in the run-up to D Day. Both entrances were  finally bricked up in 1963 .

The Penarth Subway toll house stood where Plas Pamir is now. This one one of photographer Ben Salter's remarkable archive pictures (Photo Ben Salter)

The Penarth Subway entrance stood  where Plas Pamir is now. This is  one of  Ben Salter’s remarkable local archive pictures (Photo Ben Salter)

In 1976 part of the Penarth end of the tunnel was excavated and some cast iron was removed but the rest of it was left in place.

In April 1991 the Cardiff Bay Development Corporation (the body formed to re-develop Cardiff Bay)  thought about re-opening the tunnel as a pedestrian link between Penarth and Ferry Road. When consulting engineers Brian Colquhoun & Partners  opened up the subway and investigated its condition they found the tunnel was still sound, and water ingress was only “minimal”. It’s still there today hidden and forgotten beneath the bed of River Ely.

It would have cost only £1,000,000 to refurbish the Penarth Subway. The Pont-y-Werin Bridge across the Ely cost £4,500,000 .

David Carter’s remarkable on-line archive on Penarth Docks and the Ely Tidal Harbour is on

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  1. I uesd to cycle through the subway when I worked in Spillers. It was always exciting because cycling was forbidden and you may have been caught doing so. In the winter it was no joke going up Ferry Road at high tide on a windy day. One pedalled furiously through the water blowing in from the bay. But the bonus was hanging onto the back of a passing lorry going towards town. Dangerous because of crossing railway lines. No Health and Safety in those days though!i

  2. Helen says:

    Congratulations to Mr Carder for this fantastic website, a feat in itself. It’s so beautifully written, informative and entertaining. Very glad and grateful he has given all this time and skill to such an impressive historical project. I’m working my way through, loving every bit of it. Thank you.

  3. But talking of Health and Safety, I did catch my pedal on one of the projections, at a join of the tunnel sections, which threw me from the saddle to the damp concrete floor. I limped up the Cardiff end and bravely continued my journey nevertheless.

    • snoggerdog says:

      i worked for moonfleet marine in 1960 ,my two workmates & i used to ride a borrowed? motorcycle through &back the subway in the lunchtime ,those were the days !

  4. Tony Bennett says:

    I remember my grandfather taking me through the tunnel led by the rear light of a bicycle being pushed along (there was no other illumination). If the tunnel was bricked up in 1963, then I would have been 7 years of age (or less) at the time.

  5. Johnabutt says:

    Spend another £10,000,000 and Penarth could have another way to Cardiff for cars. If only!!

  6. penarthgirl says:

    This brings back some happy memories of my childhood in the early 1950s when I was about 10 or 11. Our friends, my cousins, my sister and I would walk from where we lived in Paget Terrace all the way to the subway. Then we’d walk through, singing a boy scout/girl guide song, “My Tall Silk Hat” at the tops of our voices because we knew all the words, and we loved the way we sounded in the big echoing space. We’d walk downhill and then uphill, balancing on the pipes, dodging the drips coming from the top, until we got to the other end and after a while we’d come back through again doing the same things, then making our way up Dock Road to home. Simple stuff, but loads of fun and plenty of fresh air. We didn’t tell our Mothers though, because we’d been forbidden to go there on our own.

  7. David Carder says:

    Thnaks to the Penarth News for posting this – if your interested in history please visit our website at and you are very welcome to post your recollections and comments at the forum as well.

    • penarthgirl says:

      I’ve visited the website and find it fascinating. I’m still working my way through it and have posted my memories of the subway. I really appreciate Mr. Carder’s dedication to this amazing feat of engineering and my husband marvels at the engineering pattern-making involved at the very beginning. Thank you PDN for posting the most interesting piece of news in a long time..


  9. Keith Lenahan says:

    Often walked the tunnel as a lad, 1950’s. I remember the way the apples we had scrumped would echo when thrown as they bounded down the tube. Happy days.

  10. Tog says:

    Reblogged this on sideshowtog.


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  13. Roger Pratt says:

    I remember going through the subway in 1963 at which point it was closed but the boarding-up had been torn off and people were still using it. I was with my bike. There was no lighting except my feeble Ever Ready lamp.There was about a foot of water at the lowest point. I hadn’t realised that it was closed but needed to get quickly from Penarth to Grangetown.

  14. I certainly remember going down it after 1963, with my friend Jenny Edwards. We started off at the Penarth end the old Police Station still had loads of old paperwork about arrests etc. It ways pitch black and we scared ourselves silly, we got through to the Cardiff end, but then had to walk back through.

  15. James Evans says:

    I regularly used to go to Penarth via the Subway as a lad in the fifties with a friend. We used to coast down to the bottom of the tunnel on our bikes and then push our them up the steep climb to the exit. As I remember it there was a kink in the lower section and the tubes that ran through the tunnel were streaked with red lead that we thought (at the time) could have been blood of boys falling off their bikes. It was really quite spooky, dark and frightening but this didn’t stop our many adventures.
    We also used to visit the mothballed naval ships that only had a skeleton crew for security.

  16. Roger Pratt says:

    The last contributor mentioned the mothballed naval ships which I can just remember through the mists of time. Were they US navy? When were they there and where did they go to be broken up (I assume?) Giant’s Grave at Neath?

    Then there were the Pamir and the Passat, the German sail training ships. And the aircraft carrier, the Campania, which brought a Festival of Britain display in 1951 or was that in Cardiff Docks?

    Happy days!

  17. Kath says:

    I remember sneaking in to the Penarth end with my dad when I was a child in the 80s, sticks vividly in my mind.

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