Obviously picking the greatest bridge engineers is open to all kinds of interpretations but hey, someone has to make a list. The engineers I have chosen have a number of things in common, they have moved the art of engineering forward while designing structures that are beautiful and stand the test of time.
You have to be an engineer (naah to architects).
You designed the bridge (actual structural calculations in addition to the concept).
The design is a structurally reasonable bridge (meaning good engineering involved).
Your bridge is attractive (eye of the beholder, in this case my eye).
I was just writing about adding greenery to a bridge a few posts back and voila, they already did one in Vancouver, Washington. Most pedestrian bridges look best when you are approaching them from the roadway. They are designed to be seen as a whole structure. This bridge takes a different approach and is geared towards the pedestrian crossing the bridge. In the Aspire magazine article you get some photos showing the meandering pathway across the bridge, lined with planters, and inlaid colored pavers.
My overall opinion is that it is a nice structure and the “strolling in the garden theme” is appealing but it’s not really a bridge. The bridge is secondary and just a means to an end. The landscaping is a little overdone compared to the landings on either side of the bridge. Maybe if it ended in a great sculpture garden and the bridge was the entrance to the park or to a museum?
When I first received my engineering degree I tried to get a job in Oregon. Eugene to be specific. My wife was offered a job at the University and I needed to find one. The best offer was to be the construction engineer on a new pedestrian bridge over the Willamette. The problem for me was, they had to be the winning bid on the project. And of course, they came second..
Hey is an old blog post by a local Oregonian Architect (and fellow Canadian!) about a highway bridge over the Willamette. It gives some outside views of how a DOT chooses a bridge that I think is worthwhile reading. I like the fact that they care enough to speak out about the project. I was wondering when the last time a group of engineers wrote the paper complaining about a design?
Quote I don’t like but throw in engineers instead of architects:
It was important that architects weigh in on this topic. We rightly should be regarded by the public as leading voices on issues related to the built environment.
I have had a spam attack in my comments section, so if I deleted your comment, sorry about that.
I received a great comment from the Happy Pontist about my quick post on design choices.
I have included it down below because I think it is important for engineers to be aware of the decisions being made on a project. I have suffered through a number of projects where other “helpful” entities (think other offices or engineers) have “suggested” design directions for me. (I sure love air quotes, huh)
These suggestions are often required suggestions but the party giving the recommendations typically do not back up their advice with their signature. Being a professional engineer is a lot of responsibility and signing a plan should take a lot of thought.
Some great advice for engineers from H.P. (who always says it better..sigh)
This is maybe related … In the UK, we have a legal obligation when designing a bridge to consider how it will be safely built, used, maintained and eventually demolished. Often, designers only pay lip service this to requirement. Those of us who take it more seriously, however, are often frustrated when clients and others take decisions that in our view, reduce the safety of these activities e.g. a client who doesn’t want an access walkway or ladder because it spoils the appearance. When filling out the paperwork to record what I’ve done to meet my safety obligations, I make a point of recording the design decisions that I disagree with and which were made with others. The public will never know, but should the legal people every come after me, I’ve made sure the people responsible are recorded.
Something else I’ve done on one project is to produce a commentary on the design – why certain decisions were made, by whom, etc. Again, not for public consumption, but for the information of designers who may come later in the process. And again, it’s a good way of recording decisions made that you disagree with, although clearly it won’t be welcome on many projects!
Mr. McCullough became the State Bridge Engineer in Oregon in 1919, only six years after graduating from Iowa State University in 1910. (A partial list of his bridges is here witha nice summary of his career. I would imagine he had help with the actual designs.)
As a bridge designer I admire his structures for their beauty and elegance but what I most admire is the fact that he did all these structures without a computer. I look at the bridges and think, “how the hell would I design that?”. No cadd for layouts, no calculators, no Internet! Yikes, what did they use an abacus?
Take a look at some of his bridges and tell me if you could design them using the tools of 1919. I wish I had the opportunity to build just one concrete arch like the one below. I would be a happy engineer.
Its been a busy week and its only Tuesday! Projects to finalize, emergency repairs and teaching have slowed my posting ability. One of the things that did bother me enough to get off my butt and write a post is the issue of design choices.
By that I mean how do the choices of others affect your design. (Really, I mean my design) For example, if you are working on a bridge repair the decisions of the traffic engineer will affect your plan. Staging, temporary barrier rails, lane closures may all come into play. If your designing a bridge, you face a large number of previously made choices that point your design down a path you may not have anticipated.
What I am really dancing around is the question of control. What happens when the designer has to sign for poor choices made, concerning a design, by “others”. (I’m really trying to stay out of trouble here…) I realize this happens to engineers all the time, but I am wondering how the public judges the final outcome?
I am really screwing this post up. Maybe I can sum up what I am trying to say by suggesting that all engineering plans should have a box on the front of the plan set saying “in spite of all the poor decisions, I did the best I could”. And yes, I am having a bad day….
Its Friday and today I gave an overview of the development lengths required for reinforcing steel. If there ever was a duller class to teach at 7:30 in the morning, I have not come across it. (And the day after the midterm exam, yikes)
I’m a bridge designer who uses the AASHTO code but the course uses the American Concrete Institute (ACI) building code and commentary. I did find a handy guide by Dayton Superior, outlining bend diameters, hook lengths and other riveting facts about reinforcing steel. Download the pdf here. (Sorry, US units only)
Update: #2 – I put a link in my blogroll to a Bridge Costs Spreadsheet (excel). As I add costs to the sheet I will upload the latest version. (It does NOT contain anything else.) It is pretty plain but I will work on it.
Comparing the costs of bridges is a tricky thing, especially when you get into signature designs. But some measure of cost may help to evaluate the differences between designs. **Remember if you are buying a piece of Art, money is not the driving force behind the decision.
The most common cost for a bridge is the lump sum value but often engineers break that down into a square foot or square meter price. (I grew up with the metric system in Canada now I teach US units..) Additionally, the cost per square foot can be based on the roadway width, pedestrian width or the entire width of a bridge. To keep things easy I will use the entire width of a bridge for the cost area.
Bridge costs: (Using 1.6 US dollars to one British pound)
I started with my bridge and some others I found on the internet. (Everything is factual on the net, right?) The lengths and widths may be off but it gives a starting point for adding the cost dimension to the discussion. How much is too much, that all depends on who is paying.
I will start a database and post the costs as I find them. I know the Happy Pontist has provided costs for a number of pedestrian bridges on his/her blog. So that is a great resource for seeing what you get for your money. If you have some bridges to add to the list, please forward them.
My last post showed a bridge concept over what I thought was a river but was instead a railroad system. (Seems fairly obvious in retrospect, thanks HP) But I still thought the trees lent a natural component to the bridge, which reduces all that harsh concrete. As an engineer I would hate vegetation on a bridge but as a pedestrian I think it would be very enjoyable.
Urban bridge gardens would be fun but I can see the problems. Leaves, brush, weight, water, missiles for kids, and a variety of other problems. I have seen some bridges with small planter systems but never any trees. Has anyone seen a bridge with trees on it? (Send the link!) I doubt any engineer has designed one but I would love to try!
I followed the link on the Happy Pontist to this bridge by cepzed designs in the Netherlands. The bridge will be built in Utrect, the fourth largest city in the Netherlands. (Hey I can google)The bridge has great access to the river(?) through openings in the bridge. (Although the image does not show the railing required to stop pedestrians from falling into the holes, yikes) It also looks like it could be built at a reasonable cost.
I think it is a very appealing design but the first thing that came to my mind was, how will you drain the water from the trees? Also how will a growing tree change liveloads as it grows? So, the first I think of, is the challenges of determining the loads, the span arrangements, and the construction sequence. I must be an engineer.
Take a look at the design and think about what comes to your mind. Me, I am going to go look for more bridges with plants on them.
The happy pontist has a number of good posts on tensegrity bridges. I never knew they existed but I am not a fan. I can’t stand pointy things and while it is interesting, the chaotic appearance hurts my head.(I’m not worthy)
Also from a HP is a great link to the deputy dog website and TRIDGES! I want to design one! deputy dog also has some great pictures of a round bridge.
So if your a bridge designer you have probably faced one of these scenarios.
You prepare design cost estimates for alternative bridge designs. Maybe one concept is a concrete bridge and the other is a steel bridge. The client picks the lower cost alternative. Late in the design, costs are reevaluated and the chosen concept comes in higher than previously thought. Not just higher but really higher, maybe twice what you originally calculated. Now you are late in design and the client is wondering if the wrong bridge type was chosen. Do you continue and justify the design saying “well both alternatives would have doubled in price, so no problem”. Or do you redesign? ( A dreaded word in engineering.)
A city wants a new signature bridge. A budget is set and a design competition is held. The winning design is guaranteed to fit in the budget. The engineering firm gets heavily into design and determines the bridge budget has increase by 50%. But the bridge has been scheduled to let next year and a redesign is not possible.
You see this all the time in engineering. The initial budget always seems to go up. Engineers require a fully fleshed out concept to determine the loads and the final structural element sizes. It is very difficult to redesign because that often means starting with a brand new model to develop the loads. Even a small change may slow do the final design.
One of the solutions is to spend some time evaluating concepts before starting. You would think this is an easy answer but it requires an engineer with a great deal of experience.
Most owners don’t want to hear that their new bridge will double in cost. Some designers are happy to go along with the low cost estimates because they know that a redesign will not be possible late in the game and the owner will find the money. Other times a good concept was just let at the wrong time.
The Architectural Record is a great website covering all thing Architectural. If you search their site using the word “bridge” you get quite a few interesting projects.
Another site has a good article on Architectural criticism. Eikongraphia. Seems they are having the same questions about how to critique a structure as we are..but I have to disagree with the comment about having a neutral viewpoint. A well reasoned point of view adds a great deal to the understanding of a project. You can’t disparage a structure without also explaining what would make it better.
Q. Architects are ninjas?
A. Not all of them – but most, yes. Think about the similarities: both have underground extensive training in multiple defensive and offensive arts, neither sleep [its the cousin of death], both know everything about everything – and are constantly schooling the masses, both exist best in total harmony with their environment, both [well, most] operate in the background – manipulating the world around them without the knowledge of the masses.
Cool graphic: (check out what it means on the site:)
This is probably common knowledge but Google is sponsoring a bridge competition for their Sketchup software. Sketchup is a marvel. A free 3D drawing program that is easier and more effective than any other 3D software I have seen. You can draw your design quickly and to scale.
One of the presentation covers the Parkview Avenue bridge over US 131. A 249 foot, 4 span all precast bridge. The cost came in at $2.84 million, with a build time of 2 1/2 months instead of the typical seven months. They used webcams to view the project and precast round pier columns. It is worth downloading the powerpoint and video. (Note: the file is zipped and around 64 MB)
The other presentation covers a pre-fabricated bridge. It shows the Texas prefabricated barrier system. (Smaller file download)
The Castleford Bridge is an interesting “S” shaped pedestrian bridge, linking “the north and south parts of town at Aire and Mill Lane.” It utilizes sustainable lumber and lighting under the handrails. The bridge is very beautiful but how could you build anything that would take away from that stunning view.
I have written about this before but I am always curious about taking credit for a project. Who gets credit for the concept for a bridge? For example, a single span steel arch is being built in a nearby town. I promoted the idea of a single span steel arch and my roadway cross-section design is being used for the structure.
The steel arch is being designed by another consultant and it places the steel arches on the outside of the cross-section, instead of my idea for the arches next to the roadway with cantilevered sidewalks.
How much credit can I take for the final bridge? Can I show it in powerpoint presentations and state I designed the concept for the bridge?
Take this example. Miguel Rosales is showing powerpoint presentations essentially promoting his work on the Leonard P. Zakim Bunker Hill Bridge, over the Charles River. Nothing wrong with that but what was his role in the design?
He is quoted in one newspaper - “Menn has been credited widely as the designer of the bridge, but Rosales is not shy these days about claiming credit for his own role in the project, which he said was substantial.”
Also with this particular irksome comment:
A central thrust of Rosales’ career is that, as an architect, he feels he brings a special aesthetic sensitivity to bridge design that many engineers lack.
The concept and character of the bridge belong to the genius of Menn.
I realize engineers typically shy away from taking credit or promoting themselves but I think it is a necessary part of raising the status of our profession. So make sure the right person gets the credit.