Bridges to Nowhere – for now

Pedestrian bridges, often called foot bridges, have been both separate from and part of vehicular bridges. As separate structures they were often constructed in rural or wilderness areas tied to trails rather than roads and were designed with a rustic look.

However, pedestrian bridges associated with urban areas are in demand now and often include bicycle usage. As shown by the three bridges presented here, the reduced scale of urban bridges and their proximity to human beings and nature no longer call for a rustic design.

Despite the fact that these three bridges have gained praise and publicity, the present economic downturn has given them uncertain futures. Hence the title “Bridges to Nowhere—for now.”

THE ST. PATRICK’S ISLAND BRIDGE, CALGARY, CANADA

Rendering of the St. Patrick's Island Bridge, Calgary, Canada

The St. Patrick’s Island Bridge in Calgary was designed in 2009 by Endres Ware* and Ammann & Whitney**, as a gateway to the activities of the island’s Centenary Park. The two-part bridge will also frame views of Calgary and the Rocky Mountains.

The bridges connect to a central platform located where they meet on a mound of earth to be constructed on a site in Centenary Park. The rendering shows a curved path on a mound leading to a ramp lifted up and attached by some of the cables to another land form behind the main pier. The bridges’ low arches, also visible in the rendering, rise just high enough above the underlying flood plain to avoid possible flooding but will not block views of the surroundings.

The bridges’ structure allows the weight of the concrete decks to be carried by a series of main cables running up to the two masts from which backstay cables transfer the deck’s weight back to the ground.

Site plan for St. Patrick's Bridge, Calgary

The two separate cable-stayed bridges, one longer than the other, span the Bow River flowing by the city of Calgary.

Night rendering of St. Patrick's Bridge, Calgary

The masts are bent to reduce their height. The main cables are strung evenly along the length of the masts; the backstay cables, gathered near their tops, are “harped”, meaning that the cables have different lengths.  They cables splay from the top of the mast downward and extend to the adjacent bridge, which reduces the amount of force necessary for their anchorage and allows the bridges to brace each other horizontally.

The bridges appear to bow to their respective destinations, the city and the neighborhoods on the riverbanks. One hopes that users from both places will be able to respond with their feet to their salutes in the not too distant future.

18 Responses

  1. Tom Lease says:

    I like Michael’s post. I live drive by the 1-80 bridge often and think it is rather lacking for such a high profile – highly visible area in such a progressive forward thinking community.

  2. roro says:

    its abenefit searsh .
    thanks for the good news

  3. Ann, thanks for the good news about the global trend toward pedestrian bridges!

  4. Ann Thorpe says:

    I enjoyed these last posts, too, and in my research on design activism I also came across a number of bridge projects that aimed to reconnect people (non motorized) and places. An encouraging trend and the pedestrian bridges (e.g. some of the newer ones we have here in London over the Thames) are great fun to use too!

  5. Thank you, Michael, for this very thoughtful comment!

  6. Michael Corbett says:

    Sally, These very modern, sculptural designs conjured an evil twin — the bridge over I-80 in Berkeley, which raises the whole issue of the community for which these things are done. With the College of Environmental Design and the city’s tradition of social innovation, etc. how did we get a bridge from the first half of the 20th century while Pittsburgh, Fresno, and Calgary, which we might sneer at because they don’t eat locally grown organic food, get bridges whose designs deal with issues of our time? We got a Tea Party bridge and they got bridges for climate scientists and other members of the reality based community.

  7. Paul Endres says:

    The bridges have been looked at from a green perspective. Typical engineering analysis attempts to both minimize material and labor reducing it’s carbon footprint. From a design perspective we have attempted to do that. In the west end bridge we will be using recycled materials and “greener concrete” using either slag or High fly ash. 100 foot sections will be barged down the river and erected in place without typical shoring. The design incorporates the existing bridge as the shoring used to erect the segments in place reducing labor and potential pollutants in the river. Modern materials (steel, concrete) solve both the energy required to produce a bridge and reduce the amount of material necessary as opposed to materials that may appear to be more traditional or what one would think of as green that limit the possibilities (spans, etc).
    A ‘style’ otherwise need not be more green or less green, the materials seem to be more of an influence in my opinion.

  8. Himanshu Burte says:

    Thanks for the post. The bridges really look very elegant. However, since I am much interested in sustainable architecture, I am curious about how ecologically sensitive (or ‘green’) these designs are compared to other possible options for bridge building. Were more energy efficient materials and technologies of bridge building(which might or might not appear ‘contemporary’) a real option in these projects?

  9. Excellent. Thank you Paul Endres! The maximal effort to achieve such sleek and evocative minimalisim is an important story.

  10. I hope this explanatory comment by Paul Endres will inspire others to post comments because they really do add to the meaning of the article.

  11. Paul Endres says:

    In the case of the West End bridge, the design really was based on two idea’s. The first was to connect both the banks of the Ohio river and the communities of each side while clearing 65 vertical feet. The next was to move the pedestrians away from the traffic while preserving the historic elevation of the bridge and improving the historical bridges performance. We “self anchored” the bridge to reduce costs and use the stone towers as support for the new walkways. Although, the design appears minimal, a great deal of design was necessary to streamline the structure, pathway, and architecture in one graceful bow. We approach all the designs in a similar way, one in which no component can be removed without changing, the space, architecture and structure.

  12. Sally Woodbridge says:

    Jay Claiborne,
    Thanks for the thoughtful comment. Maybe we can all chime in on the new Bay Bridge when it finally opens!

  13. I think I appreciate most how informative these short essays and pictures are about a very compelling type of project. In some ways, the Lewis Easton Bridge is the most dramatic because it is in such contrast with the setting, but visible from a major highway. They become a kind of signage, a built object to further dramatize environmental grandeur. I look forward to a future report on the pedestrian/bike portion of the new east span of the bay bridge.
    Jay Claiborne

  14. Thanks, Sally. I was wondering more about the effect that the existing bridge might have had on Ware’s thinking as he designed — in other words did he think of the stone piers as foils for his light tensile structure?

  15. Jay,
    Perhaps we are, as usual, following the lead of Europeans like Calatrava who crossed the ocean to create the much admired pedestrian bridge near Redding, California

  16. Dan – as was the case with many older bridges, I don’t think the design of this one took pedestrian use into consideration.

    Thanks for commenting! sally

  17. Jay Turnbull says:

    Wonderful story, and images, Sally. I wonder if bridges are so eloquent because the program is blessedly simple: a beginning, an end, and a necessary span!

  18. Fun to read about these tautly elegant designs. The Pittsburgh pedestrian extension seems a very different sort of commission for Endres Ware in that there is a strong existing bridge context and I wonder how that might have affected the design process and esthetic outcome.

Leave a Reply

Your email address will not be published. Required fields are marked *