London's latest canal bridge rises and falls
like the opening and closing of a fan

| 21 comments

Merchant Square footbridge by Knight Architects

British firm Knight Architects and structural engineers AKT II have completed a moving footbridge in Paddington, London, that opens and closes like the blades of a traditional hand-held fan.

Merchant Square footbridge by Knight Architects

Consisting of five steel beams that rise and fall using hydraulic jacks, Merchant Square footbridge by Knight Architects and AKT II spans a 20-metre width of the Grand Union Canal in Paddington Basin, close to Thomas Heatherwick's Rolling Bridge that curls into a ball.



The architects, who specialise in bridge design, won a limited competition to design the crossing in 2012 with their plans for a "kinetic sculpture" that could rise to allow canal boats to pass along the waterway.

Merchant Square footbridge by Knight Architects

Opening in sequence, the bridge's five beams rise to different angles to create a fan-like effect. The first rises to 70 degrees, while the last lifts high enough to create a clearance space of two and a half metres over the surface of the canal. The weight of the beams – which range from six to seven tons – is balanced by a 40 ton counterweight that keeps the beams steady as they rise and fall.

When fully closed, the bridge is safe for pedestrians and offers a three metre wide crossing.

Merchant Square footbridge by Knight Architects

"Shaped counterweights assist the hydraulic mechanism and reduce the energy required to move the structure," explained the architects and engineers in a statement.

"The bridge balustrades are formed from twin rows of inclined stainless steel rods, overlapping to form a robust yet filigree and highly transparent structure."

The handrail formed by these balustrades features a built-in strip of LED lighting to illuminate the crossing at night. Like Heatherwick's bridge, the structure opens every Friday to let boats sail past.

Merchant Square footbridge by Knight Architects

The bridge is part of a wider regeneration project for the site, with future plans including a garden square with an events space and water maze. A total of six new buildings will be constructed, with three already complete.

Photography is by Edmund Sumner.

Read our interview with project architect, Bartlomiej Halaczek:


Anna Winston: Can you briefly explain what the project is and how it came about?

Bartlomiej Halaczek: It is a short-span lifting footbridge designed to provide a shorter link between the Sunset Terrace and the new park at the Merchant Square site with the urban fabric south of Paddington. It was the result of a competition for a new pedestrian connection replacing the irreparably broken "corkscrew" bridge that was crossing the canal at the same site. The focus, both of the clients as well as the designers, was to design a beautiful and memorable structure that is modest in its appearance most of the time, but when raised, it generates the "wow" moment.

Anna Winston: How did you develop the idea of these five separate blades that lift almost independently?

Bartlomiej Halaczek: The design has been influenced by many different factors. Most important, of course, was the structural concept, and the choice for a lifting bridge. A fixed structure wasn't viable at that site as the constraints wouldn’t allow for the ramps necessary to get above the shipping envelope. A moving structure however would have to be maintained, and as these are usually quite significant costs, we had to keep them low by not overcomplicating the structure and picking a relatively simple mechanical system.

A bascule solution operated with hydraulic rams was not only quiet, reliable and low-maintenance, it also offered the desired visual drama, when an understated horizontal every-day object suddenly stands up pointing at the sky. Subdividing the structure into five independent objects made it unique without greatly increasing the cost, as there was effectively only one-fifth of the tonnage to be moved by each hydraulic cylinder.

Merchant Square footbridge by Knight Architects

As structural elements, although visually sculptural, the counterweight fins provide balance to the deck beams which helps reducing the size of the hydraulic rams. The appearance of the bridge follows the general concept to create references to the industrial history of Paddington Basin, a theme that has been carefully applied by the site developer European Land. Last but not least, the bridge becomes a further addition to the collection of beautiful and spectacular bridges along Paddington Basin.

Anna Winston: Can you tell me a bit about how the bridge was built?

Bartlomiej Halaczek: The main bridge structure is made completely out of steel, each finger fabricated and painted in North Yorkshire and then shipped to London. On site, the counterweight fins were filled with concrete and sealed with steel plates from above. The total weight of each counterweight can be read on the tips of the fins. The parapet is made of brushed stainless steel tubes with a durable handrail made of Iroko wood.

Merchant Square footbridge by Knight Architects

The most challenging part of the fabrication was the required accuracy. For safety reasons, gaps between the beams had to be no bigger than 3mm over a length of 20 metres! As impressive was the fabrication accuracy of the conical counterweights, which sink into the engine room turning into a set of walkable steps flush with the granite slabs around them. The quality of the engineering is absolutely remarkable, and great credit goes to SH Structures in North Yorkshire who turned a lot of fun in Grasshopper and Rhino into a solid piece of engineering.

  • Stophourus

    Stunningly beautiful, but where are those canal boats even going?

  • No question, looks amazing, but why is did they build an openable bridge at that spot? It doesn’t look like it is necessary to have one at that spot.

    • Ryan Clarke

      Exactly!

      Are we missing something here: “their plans for a “kinetic sculpture” that could rise to allow canal boats to pass along the waterway.”

      I’m not so familiar with London, I don’t see much room for canal boats as this is a bridge across a dead-end/cul-de-sac of a waterway. If this is the case then this is a waste of money. Beautiful design… out of context = waste of money.

      • smack

        It’s apparently a legal requirement that any bridge built over a canal in London needs to lift to allow boats through, even if it’s just to a little canal cul de sac like here.

        • Ryan Clarke

          Thanks for clarifying. Unfortunate that this subject was not covered in the original reporting.

  • Logan Hendricks

    Fantastic! Sculptural and functional.

  • Edward Scissor-Bridge.

    The counterweights are perfect for crushing people. This scheme is much better than the massive, over-budget, rethought function nightmares they’re practicing elsewhere in England.

  • ivan.capitani

    It isn’t dangerous, isn’t it?

  • KD1two3

    Like, why wouldn’t you just go around?

  • Hugo

    What waterway?

  • nsp

    The last bit doesn’t appear to rise too much over the water’s level, does it? Can it go up higher, or is it just for teensy boats without a mast? I see the point design wise, but I can imagine that it leaves something to be desired in terms of functionality.

    • MNT

      The lowest span lifts sufficiently to allow narrow boats (canal boats) to get passed the bridge. Whilst there is very little canal beyond the bridge, it is a Canals and Rivers Trust requirement to allow boats along the full extent of the canal.

  • antonomasia

    BELLISSIMO.

  • A bridge that’s not really necessary, unnecessarily lifts up with equally unnecessary complex mechanism! I just love modern follies!

  • kozlucha

    Freddy Krueger :)

  • Knight Architects

    Thank you for your comments. It may help to explain the bridge was required by the planning authority to replace an existing footbridge, which was no longer functioning and which obstructed the new development. Legal access to the end of the dock for (infrequent) canal traffic required the bridge to be an opening structure and the developer saw the opportunity to commission a design which provided both function and delight. Safety in operation and simplicity of mechanism were both considered at all times in the development of the design.

    • Phil

      Great design. Much, MUCH better than other bridges even in close proximity, but you are real designers on the job… Not any person calling themselves a designer and waving their hands in the air with an idea for a bridge. Noticed there are no trees on it. Good to see you have the design maturity to not have to resort to that.

      Congratulations. Great design.

    • Now that the canal situation is explained, this project makes complete sense. This is a visual folly added to a dead-end canal for interest and public enjoyment. Thanks.

  • Chilli

    It’s like Heatherwick’s Olympic park sculpture and folding bridge had a baby. Nice.

  • Congratulations on this piece. A wonderful example of how to turn function into beauty with a real sense of occasion.

  • Chris Torey

    There’s never a shortage of money when it’s to be spent in London while the rest of the country gets f*cked over.