CLOSED: South Dock Bridge - developed design stage

This consultation has now closed.

• Bridge design

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  The designed bridge is a variable depth steel beam with two spans and a single central pier in the South Dock. Each span is approximately 35m long, bringing the total length of the crossing to approximately 77m including the north abutment. It provides a permanent 15m wide and 3m high navigable channel for smaller boats to pass underneath. The north span is movable, using a bascule mechanism, to provide a 25m wide channel without height restriction for taller ships.

  The deck varies in width from 7.8m on the South Quay to 15.4m on the North Quay. A triangular void in the movable span directs people away from the emergency staircase located in the axis of the crossing at the north end.

  
  

  A concrete enclosure at the north end of the bridge, below the walking surface, hosts the mechanisms needed for the bridge to open and a counterweight. This counterweight helps to reduce the forces and energy needed for the operation, making the project more sustainable.

  The bridge will not only improve connectivity in the area but will become an attractive element to visit. It will be accessible to every user thanks to the wide walking area and smooth slopes.

• Bridge aesthetics

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  Most of the respondents to the initial consultation said they would like the bridge to be elegant, unobtrusive, and contemporary, with a neutral finish. Some feedback suggested the new bridge should reflect the industrial heritage of the area.

  The bridge has been designed to respond to this feedback. The design was produced to meet the following objectives:

  • To improve inclusive transport to support sustainable growth on the Isle of Dogs.
  • To provide clear routes and an attractive crossing experience for users. The emergency staircase on the north quay shall not only not restrict functionality but become an opportunity to make the design unique and distinctive.
  • To contribute to place-making and to provide an attractive landmark in the area.
  • To enhance the local identity of the area responding to both its present and past.
  • To be elegant when closed, visually unobtrusive when seen from a distance, but beautifully sculpted and detailed when seen close up.
  • To be striking and elegant when opened.
  • Not to completely block, open or closed, the valuable north-south views along the bridge.
  • To make subtle references to the industrial/commercial past of the area when closed.
  • To suggest, when closed, what will happen when the bridge opens.
  • For the moving span to have an aesthetically pleasant underside (very visible when the bridge opens).
  • To minimise the number of supports in the water and to provide a light design.
  • To have materials that are appropriate given the architectural value of the site.
  • To provide spaces for pedestrians to wait on the bridge when the north span opens, rather than having to wait on the dockside.

  The latest design meets all these aspirations. It is slender and unobtrusive, with a sculptural unique geometry. The void created on the deck of the main span not only guides users away from the emergency staircase on the north quay but makes the structure lighter and more transparent, distinctive and memorable when the bridge is open, allowing views through the deck.

  

  
  

  
  

  

  The steel structure of the bridge has been elegantly and subtly shaped to create light and shadow contrasts on its surfaces. This not only adds interest to the bridge form and makes it look lighter, but also helps to pay tribute to the area's heritage. The bridge resembles the soft curvy shapes of the base of the historic cranes that were once along the quays, or the hooks workers used to handle goods when the site was a commercial port.

  Engravings on the steelwork at the north ends of the structure suggest how the bridge will open and are also a nod to the history of the site. Colours are neutral as per the feedback from the initial consultation, having used an elegant and complementary range of greys that makes the object blend with its surroundings.

• Bridge operation and constraints

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  The initial consultation responses made clear it was important to maintain access to the dock area for leisure activities and to ensure that larger vessels can still access the dock once the new bridge is built. The responses also included a wish for the new bridge to be swift to open and close.

  The bridge opening mechanism and span will allow for a 25m wide navigation channel with infinite headroom that will guarantee accessibility to the dock for larger vessels when the bridge opens. It is expected that the bridge will open twice a week as an average. The closed bridge will guarantee a 15m wide and 3m high permanent navigation channel that will allow for some leisure activities.

  

  The movable bridge type that has been selected (bascule bridge) is commonly known as the fastest of all the mechanical options. However, the opening speed doesn't only depend on the mechanism but also on the time to clear the bridge of pedestrians before it opens. Design decisions, such as the use of hydraulic cylinders or a counterweight that fully balances the weight of the main span, improve the opening speed compared to other solutions. It is estimated, at this stage, that it would take 90 seconds for the bridge to open or close. However, the whole cycle will include other activities such as the time to open and close the gates, to clear the bridge deck or for the vessel to pass through.

  The potential impact of east-west cross winds on the bridge were raised as part of the initial consultation. The latest design is more compact, with a smaller vertical envelope exposed to wind, especially in the area that is less sheltered by the buildings. The main span now has an A-shape design that provides a more natural structural layout to transverse wind loads, especially in the open position.

• Movement, access and landscape design

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  The initial consultation revealed some concerns about the lack of segregation between pedestrians and cyclists over the proposed bridge. Concerns were also raised about the impact this would have on both bridge user conflict and bridge user safety. In response, and as part of the further development of the council’s wider Cycling Strategy, a decision has been made that South Dock Bridge will no longer provide a primary cycle route to and from Canary Wharf. Instead, cyclists will be required to dismount from their bikes before crossing the bridge. As an alternative, the council is working with TfL to provide strategic cycle routes and improvements around the perimeter of the island rather than through its centre. This includes cycle access to Canary Wharf via Wood Wharf, Westferry Road, West India Quay and improved cycle access via Manchester Road. These routes cover both sides of the Island offering cyclists comprehensive access.

  Landscape design

  Feedback from the initial consultation also suggested the approaches to the bridge should be spacious and free of obstacles. The proposals for the landscape of Upper Bank Street, at the north end of the bridge, are currently being developed and will create a wider and more direct route compatible with the geometry of the structural slab the landscape sits on, as well as the accessibility to the buildings on the area. A new ramp, significantly wider than the existing one and with an accessible gradient of less than five per cent, will provide a more convenient approach.

  The new public realm and park part of the South Quay Plaza development on the south quay includes improved pedestrian connections between Marsh Wall and the South Dock that will accommodate the proportion of bridge traffic not turning east-west along the quayside.

  The majority of responses to the initial consultation suggested seating on the bridge would not add value and would likely hinder the movement of pedestrians and cyclists. The latest design does not include seating areas on the structure but allows for people to stop and lean on the railing at the wider area of the deck, not affecting the traffic capacity of the crossing. Seating areas close to the north end of the bridge will be added as part of the redesign of the landscape of Upper Bank Street and will be also available relatively near to the south end as part of the South Quay Plaza development.

  

  
  

• Comfort, safety and security

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  A quiet walking surface came out as an important response to the initial consultation. The new walking surface (resin bonded aggregate) will be continuous, quiet compared to a street pavement, and will provide excellent anti-slip performance compared to the existing bridge.

  Other responses said the bridge and its immediate surrounds should be well lit in the evening and on winter afternoons to ensure that users feel safe and comfortable. The bridge will include functional lighting integrated in its railings and at the bridge ends to create a sense of safety. The lighting system will naturally guide people along the different paths and will be compatible with the environmental requirements (avoiding undesired light spills on the water). The bridge will also include operational lighting to signal when it is opening or about to open, part of it recessed on the walking surfaces, and navigation lighting below the deck to define the permanent channel for smaller vessels.

  The bridge will have gates to stop people being on the moving span when it is moving or about to move. These gates will be recessed within the bridge structure. The movement of the gates when raising will naturally guide people out of the deck. The space available to wait on the structure, out of the quays, will be 84m2 on the North Quay and 227m2 on the South Quay.