I just published a book of photographs covering the construction of the New Keosauqua Bridge.

Check it out…

The New Keosauqua Bridge by Stuart Nielsen

I have found some information about voided slab beams on different state websites. Most of the designs call for an 2-5″ asphalt overlay.  I’m using a 4′ wide by 18″ deep 50′ voided slab, with no overlay, for the county bridge.

Voided slabs speed the construction of a bridge but as one engineer told me, they will never gain acceptance on “real” roads. The longitudinal joints can break down and the lack of cover on the top surface can be problems.

Here is the link to the FHWA ABC website. It is a pretty big website but darned if I can find useful bridge details. Of course it has links to projects and you can always contact the project owners…..but it would be nice to have some workable information.

Some more thoughts on the ABC conference I just attended. From the presentations given it seems we are still in the promotion stage of ABC. Meaningful design information is not readily available (you try finding full designs on the web) but presenters indicated information was coming in the form of a design manual. (in 6 months? from PCI?)

On another note, here are some good pictures of erosion practices in Alaska. (7.3 mb pdf file)

Erosion Practices in Alaska

So for the last day and a half I have been involved in an Accelerated Bridge Construction (ABC) seminar. It has been interesting to see what is going on in the field of ABC. Most of the project presentations focused on large, traffic heavy situations. As well they should because this is where you get the most for your ABC bucks. (Meaning it is easier to justify spending the extra money on the project if it impacts a great number of drivers.)

I am currently designing a bridge on the other end of the spectrum, a County bridge, which will use ABC. It is a single span (50′) voided slab box girder bridge on precast abutments. I am designing it to be built in 7 days or less. (I’m hoping for 3!) The problem for my design   is the cost. It may well cost twice what a typical County bridge would cost. I’m working on that problem as well…..

The future of wind power is a backyard system that doesn’t kill the surrounding wildlife.

We are currently developing a Vertical axis Wind turbine prototype. Here is one solution by another company.

Wind Turbine

I have not written for a while. Still working on a short span county bridge but I have been spending time developing a wind turbine.

Good links:

Otherpower.com

How to build a wind turbine

I paper on a couple of precast bridges.

Accelerated Construction in Iowa

I few papers on possible precast beam design for low volume roads in Iowa.

Modified beam in slab bridges

Precast bridge elements for accelerated construction

Low volume road abutment design

Precast channel bridges

It looks like I will get to design a somewhat new standard county bridge. Starting with a 40′ x 30′ precast slab bridge. Hopefully when its done other counties will use it.