tallbridgeguy

You have got to love this bridge website for the Oakland Bay Bridge. With Movies!

I made the roster to give a talk on my last steel bridge design at the World Steel Bridge Symposium (WSBS), in November. I am also teaching concrete design this summer to third year civil and construction engineers.

My question is what makes a great lecture? I would really like to encourage, motivate and inform both groups but I am not sure I can. Is it possible to give a great talk to engineers? If I stress aesthetics, those engineers who favor economics will complain. If I focus too much on in-depth details I will put half the group to sleep and the other half will say I did it wrong.

I can’t really remember the last time I reallly enjoyed watching a lecture. What to do, what to do. Suggestions anyone?

Back to the questions about the Keosauqua Bridge.

Was any effort made to reuse the existing pier positions by extending them sideways? It isn’t quite clear from the images so far.

The existing piers were not in the same locations as the new bridge piers. (The old piers were reused as revetment for the new bridge abutment slope protection and select stones were cut for the touch stones on top of the new piers. The touch stones allowed visitors to touch the “past” bridge. )

Any concern that the curved beam soffits makes it look like the bridge is a series of arches (especially in foreshortened perspective views), when structurally this is misleading?

Not until you mentioned it. (Ha!) It is a fair point, it depends on where you are located in relation to the bridge.  In this case the bridge has two prominent viewpoints.

One from the sides of the north abutment where people can play in parks and further downstream from the historic Manning Hotel.

This view is looking north on the upstream side. The girders look more like arches than haunched girders. (The touch stone are on top of the pier. Stones cut from the old truss bridge piers)

Read More >>

I have been busy with grading finals for my concrete design class and of course, Mother’s Day. Bridge Design Space (by David Tsay) has a great storehouse full of interesting bridge images. Like this one.

I received some great questions about the last post that I think I should expand on, since I skimped on the reasons for the new bridge. (thanks for the questions by the way) I would have answered in a comment post but I wanted to add some images and frankly, I don’t know how to do that yet.

Given the width of footway provided on the new bridge, could the existing bridge have been retained as a footbridge?

Before replacing the truss bridge we evaluated whether or not it was possible to keep the old bridge in place, with one of the popular options being the use of the old bridge as a pedestrian bridge with a new vehicle bridge beside it. The problem essentially boiled down to money.

In 1937 the truss bridge was built on widened piers from the original 1873 bridge piers. Since we did not have any plans from that bridge it was difficult to determine the life left in the old limestone block piers and methods required to strengthen the piers would most likely rob them of their aesthetic appeal.

Read More >>

Well I want to try this bridge criticism experiment so why not start with my own design, the Keosauqua Bridge. About four years ago, I was asked to design a bridge to replace a four span truss bridge, built in 1937. The truss was on the list of historic structures and was very popular with the local community.

But the bridge had a number of problems, including a functionally obsolete width and structural deficiencies.

Read More >>

Okay I am going to start my criticism of other people designs, I have my concept hat on and I am ready to go. Lets start with the obvious, what bridge should I take on first?

Now that’s a problem. How do you judge a design from a small “artist rendering”? Often that is all you get in a newspaper or blog. A concept that may not represent the final project. For example how do you judge the worth of the concept for the new I-5 bridge over the Columbia river in Portland, Oregon. (My brother lives there so I do have a right to review through kinship)

How can I judge how 12 lanes of traffic, a light rail system, pedestrians and bikes will look on this bridge from this one view? How many people driving across the bridge get this view? How does the cross-section look? (Lane widths and barrier rails are typically engineering concerns but it affects the look of the final product.)

So problem number 1 in reviewing concepts. You need multiple images from real life orientations. I will start trying to find another one to “critique”.

Here are a selection of comments I found on the newspaper website concerning this design.

Read More >>

One of the things that I have never been taught as an engineer is how to critique a structure. Architects do it all the time as part of their core training. Take this review of a covered bridge concept reviewed in the Guardian. Finding an engineer who would say this publicly would be very difficult. Engineers are not trained to put forth and take criticism.

I wanted to take a poke at deconstructing a bridge concept. One of the problems is finding enough information and images to accurately gauge the designer’s intent. I also do not want to belittle, demean or attack a design but new concepts should be open to evaluation and discussion. As a designer, you should welcome the chance to explain your bridge.

I also received some good advice on how to start the conversation, “always be straightforward, constructive, and diplomatic!”

So, lets start slowly and please join in if you can. I would like it if other bridge engineers would like to pick a bridge and discuss our viewpoints across various blogs.

A while back I was asked to review a working version of a new website dedicated to Accelerated Bridge Construction details. The FHWA was putting the site together so that designers could submit details that they used on ABC projects and allow other designers the opportunity to see and download the concepts.

You had to become a member and log in to submit details. My initial feedback suggested that the site was clumsy (very diplomatic, I know) and was not an easy database to navigate. A very 1990’s kind of website. (it is government after all)

I also touched on the concept of credit for details. Engineers readily share details and it is often difficult to ascertain who came up with the original concept. But, I suggested that engineers would be better served if work was attributed to a specific engineer (or engineers) and any further work based on the concept, of that engineer, would be cited similar to how professors cite someone else’s work. Meaning, engineers should get credit for their work.

The American Institute of Architects puts it this way:

Perhaps the most frequent violation of the AIA’s Code of Ethics and Professional Conduct is that of failing to give appropriate credit and recognition.

I thought it would be difficult to get details from engineers if they didn’t receive some kind of recognition for their details. I also felt that by giving credit it would spark a little competition among designers seeking to improve the concepts in the database.

The website has not gone live as far as I can tell. I believe they are waiting for the new FHWA report on ABC details to be finished and then roll that report into the website. I wonder if the site will work?

Webcams are one of the best ways to moniter and just drool over interesting projects. The Nevada DOT has a great webpage showing construction of the longest concrete arch in the US. (I think)

Check it out here.