A colleague at WSP and I entered the design competition at the IABSE Future of Design competition, we were really pleased to be shortlisted (though gutted to fall at the final hurdle, obviously!) and it was interesting to see the other shortlisted entries. It is always fascinating to see you others have responded to the same brief. Our poster is here, and images from it are below:
Our poster puts quite a few ideas to the test, some of which worked well, some not so well, the good:
- Using photoshop to transform sketches – neither my collaborator nor I are good ‘presentation quality’ sketchers (although we are good enough ‘conversational sketchers’), and would usually turn to a rendered model for a competition. Photoshop quickly turned rough sketches into something of acceptable quality for the competition. There was no 3D model of the whole bridge to produce, which sped things up (but do see ‘the bad’, point 1). Most of the sketches were on top of some rough lines produced in Rhino to keep things to scale. I think the sketches are simple and clear, seem unlaboured, and are good enough quality for a poster.
- Producing a better render in Rhino – with a bit of effort, I was able to preserve the linework in Rhino alongside the rendered surfaces, this produced a better render (after some playing with the lighting) than I have managed before. I hate Rhino renders without the edge lines, so this was a step up from a Rhino screenshot without losing its clarity.
- Using powerpoint to layout the poster was just fine – no need for something more sophisticated
- Graphic statics – the justification for the design was run developed using a reciprocal diagram to demonstrate that the slightly counter intuitive ‘down-pulling’ cable worked as intended, and why it was necessary. It provided a way to put calculation onto a poster without it seeming out of place – it’s just a diagram. It was great to enter using a structural system that felt genuinely unusual and used the canyon’s sides to achieve what wouldn’t have been possible in another situation.
- UHPC – the bridge used my collaborators knowledge of Ultra-high performance concrete to slim it down even more compared to my original suggestion stone, without just using it like a ‘magic’ material
- The inspirational projects section – it felt like a great way to draw on other great projects and ideas whilst avoiding any awkwardness of appropriation or similarity
- the renders and sketches weren’t strong enough compared to the competition. Not having a 3D view of the whole bridge would have taken more time to produce, and additional space on the poster (carrying an opportunity cost), but not having one marked us out as being less polished than the other shortlisted teams.
- the text was too small and there was too much of it – I don’t think anyone read much and the quantity probably put some people off even starting. The whole poster was just too busy.
- I’m not sure at the conference (and perhaps even some of the judges) both read and really understood the graphic statics part of the poster, it isn’t a part of mainstream engineering education and can seem a bit unorthodox if you don’t know about it already. For this particular form, the reciprocal diagram isn’t especially pretty or eye-catching.
- the poster was produced over the final weekend prior to the closing entries – there wasn’t much time for reflection or iteration
A wider view:
The brief was quite interesting – put a footbridge about half way down a canyon, spanning between its two sides. Almost any form of bridge is possible, you have an endless supply of ‘skyhooks’ above and below your structure that can carry either compression or tension. As long as the bridge is light enough, you can just lift it in from the top, so you can prefabricate.
Some wilder ideas I had included:
- Have a suspended path that runs all the way up the centre of the canyon, rather than a path dug into the sides
- Just have people walk along the top of the canyon, and leave that place undisturbed, the experience of seeing the canyon from the top using a bridge is probably adequate
- Build a tunnel (down one side, below the river and back up the other), so the crossing between the sides is completely invisible from the canyon
- Transporter bridges (would need to be staffed, but carry a toll/suggested donation and that should cover it)
- Move the picnic site to the other side of the canyon, so no crossing is required, and neither is a path up the canyon
- Don’t have the picnic area at all, and do something else
So whilst I enjoyed reponding to the brief given (it’s always fun to sketch out the design of a small footbridge) I do feel it misses the an important part of being an engineer – the creation of a path up each side of the canyon needs real challenge and there wasn’t space to do that within the competition. I don’t think a path dug in like this is appropriate for a national park, in particular a special location like a canyon:
- It is irreversible for future generations, we should give them the opportunity to remove the path if they want
- Would damage the river and canyon below during its construction, which would require significant dust, noise and vibration
- Rock fall protection along the path would probably require the installation of nets above the path further spoiling the canyon
- The omission of edge protection for a path like this is strange – perhaps I and the other entrants should have omitted edge protection from our bridges, which are the same height above a drop, and are wider (albeit potentially more crowded), or at least shown the handrail continuing from our bridges on plan to show it connecting with a footpath edge protection.
An example I like is a canyon walk is in Dollar, Scotland. For the majority of its length, the path winds over the ground on bridges, leaving the carpet of vegetation largely undisturbed, and stopping visitors from straying from the path and causing additional damange.
If this were a real project, I believe the responsible thing to do would be press the client and architect on why they were constructing this path, and what other options had been explored, not just design the bridge.
It was interesting to note that the 2015 winner challenged the brief, re-siting the proposed bridge down the Thames to re-use an existing bridge. However, it still seems to be the best strategy, should you want to progress to the shortlist and beyond, to respond to the brief in a more straightforward manner. In future years, it would be nice to see an honorable mention for an entry that challenged some aspect of the brief convincingly, or even a separate prize category.