Last Word on Bridges

Cazenovia Street BridgeSouth Buffalo Blogger has written an interesting set of blog entries and has taken a great set of sickening photographs of the Cazenovia Street bridge; see them here. 

Based on my previous blog, I would not worry about driving over the bridge.  However, its aesthetics are incredibly bad.

I don’t remember much about the civil engineering module I took in my Statics class in college, but I do remember three things about bridges that indicate problems.  I’m sure there are many more:

  •     A hollow sound when hitting foundation elements with a mallet;
  •     Movement (scrape marks) of any bridge supporting points against the foundation;
  •     Joint wear

I don’t think that concrete pitting is a good thing, but if the bridge has not moved off its foundation and the foundation is not rotting from within, then most likely the bridge is not in imminent danger of falling down.

My two cents:  Rust and pitting, while really ugly, is generally not much of an impact on the superstructure as long as it’s not through and through.  It’s like having ugly siding on your house. 

Nonetheless, the photographs from the Cazenovia Street bridge make it appear that this structure needs some attention.

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6 Responses to Last Word on Bridges

  1. Cindyk says:

    What can be said about the crumbling foundation at the base of the bridge along the Cazenovia Creek? (as in the url below)

    http://southbuffaloblogger.wnymedia.net/blogs/2007/08/07/city-of-buffalo-bridges-cazenovia-creek-is-to-monitored/

    Can I add to your readers that when standing/walking on the bridge when heavy traffic or heavy trucks are crossing, you feel moverment of the structure beneith your feet?

  2. Paul says:

    If the foundation is 8 feet thick and 6 inches of it has crumbled, then the foundation is probably more than strong enough to withstand static, vertical loads. If 2 feet has crumbled then I agree that there’s a disaster just waiting to happen. If we were, say, in an earthquake-prone area it might be even more problematic. Certainly the foundation has to be resurfaced or rebuilt before the pitting becomes extreme. From my admittedly non-professional look at your photograph, I would say that it’s closing in on needing repair; but it’s not in danger of falling down (or tipping over).

    On your second point: All large structures are designed to flex – it’s what helps distribute loads evenly across the structure. You can feel most small bridges vibrate under moving loads, but this is pretty normal. If you want to see a real good example of this in the extreme, just watch a spot on the tracks at a rail crossing the next time a train goes over them. The rails will bend under the weight of the wheels a good inch or so, and rebound as the wheels move off the spot.

    Hopefully, the Cazenovia Street bridge is a worst-case example, and not a typical example of the state of the bridges in WNY.

    BBD

  3. Cindyk says:

    I am not an expert on the Cazenovia Creek, but from living near this creek for many years… I’ll talk from what I see every year. Six months from now ice jamming will begin down in West Seneca (Union Rd). As the creek rises, the flow and pushing of water and ice chunks forces its way down to where the Cazenovia Street Bridge is. I have some pictures I’ll post on my blog for you to see. The foundation is what it looks like now, how will it look after another winter of ice jamming? Do you think the foundation will still hold up after the water recedes next spring? Or the spring after that? How much time do you think this little bridge has before becoming a “danger” to communters?

    You are the only person who has come up with answers so far and the interest of finding out more is there. 😉

  4. […] is what the foundation of the Cazenovia Street bridge looks like now (Summer of 2007) and while BBD is giving some great opinions on his blog, I am putting the question out there to […]

  5. Paul says:

    You bring up a great point that I hadn’t considered: Ice floes. Ice during the winter (and any debris during high water) will scour the foundation, and the water itself puts a significant lateral load on the bridge (as contrasted with the vertical load I mentioned earlier) and can also undermine the foundation. It’s what brought down the I90 Schoharie Creek bridge in 1987.

    If you haven’t already planned to do so, I would suggest that you mark exactly where you took those summertime foundation photographs, and next year, shoot the same scene. If a lot of scouring is occurring you’ll be able to demonstrate – perhaps even to someone who might have the authority to do something about it – the amount of yearly deterioration taking place. Also, you may be able to document if the see-through gaps at street level are growing, indicating that the deck is moving off the foundation.

    Let me know when they start stripping off the asphalt.

    BBD

  6. Cindyk says:

    Thanks Paul for all of your great advice. This part of the creek is probably at its lowest level (limited rain and warm temps) but by Feb/March the creek could rise at least 15-20 feet higher than what it is now. For many years we could stand on the bridge and know the ice touching underneith. What ever water that can’t make it through down the creek backs up and floods parts of the Cazenovia Park.

    Yes, by next Spring I’ll stand at the very same spot of the foundation (if it’s not too dangerous) to capture another image. In the mean time, the status of the complaint I wrote to the City of Buffalo has been referred to the Dept. Public Works & Parks. I hope to hear something very soon on that. Thanks again.

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