As of April 14th this bridge was listed on the National Register of historic Places.
This is good news and I am happy for all those supporting this historic spans future! Had to chuckle when I read the article from the local paper...... Consulting firms lowballing the rating numbers while inflating the traffic counts is nothing new and happens every day! They make more $$$ designing NEW bridges as opposed to rehabbing OLD ones!!
Healdsburg city council voted this week to save and rehabilitate this bridge rather then replace it. Article link attached.
This message is a message of praise for Mel Amato and his community efforts and website dedicated to sharing the facts regarding this bridge and raising awareness regarding the value of preserving rather then replacing this fine bridge.
BH 43906, here is a rehabilitated bridge within 100 miles.
This interesting bridge has been rehabilitated and seismically retrofitted in the past five years. It is a single lane bridge but there is a link to the engineering group who did the work and they may have more examples.
Please visit www.healdsburgmemorialbridge.com for more information. If you are aware of 2 lane truss bridges which have been rehabilitated but not widened, please email me that info. We need examples to present to our city.
Details on the history and status of our bridge follow.
In 2007, I examined the 1979 Caltrans bridge rating calculations for our Memorial Bridge. This calculation showed an Inventory Rating of zero (actually slightly negative) and a Sufficiency Rating to 2. This was based upon "as built" drawings. This made no sense to me.
These were the ratings of the bridge when it was "gifted" by the County to our city in 1981. In 1983, our city imposed a 15, 16, 17 ton posted truck weight limit on the bridge. Virtually every city council since 1983 has attempted to replace the bridge because of its incorrectly perceived structural weakness.
After scrutinizing the calculations, I found that Caltrans had made a signification error in the location of the truss pins. The assumed the pins were located on the geometric centerline of the truss. The truss cross section is not symetric. It has a plate on the top but not the bottom. The pin should be located off-center towards the top --- and it is. This Caltrans error markedly lowers the structural compression rating of the upper truss members. When corrected to the actual locations the Sufficiency Rating rose to over 50 and the Operating Rating was fully legal.
Based upon my information to our City, Caltrans reinspected the bridge in 2008 and acknowledged their original error. The posted weight limits were formally rescinded (lifted). Visual and ultrasonic inspection of the critical tension members and pins found no fractures or flaws. The Sufficiency Rating increased to 44.2 (there are still questionably numbers in the Dead Load and Live Loads used in the 44.2 calculation).
The bridge needs a lightweight, new deck, a seismic retrofit (which has been mandated with funds earmarked since 2002), a face-lift (paint job), protective side rails and a transparent (rather than chain link) anti-jumping fence.
A replacement bridge costs double to triple the cost for rehabilitation. The bridge has 2 lanes, a posted speed limit of 15 mph and a low accident rate history with no fatalities. A rehabilitation width exception to current width standard should be possible. Caltrans has formally delegated such exception decisions to the bridge owner (our city).
An engineering option study is in process. A rehabilitation or demolish/replace decision should be made by our city by August of this year.
Please stay tuned (and pray that common sense prevails).
Craig, I just found out about this bridge's status when updating my Historic Bridge Newsroom Twitter. Its such a rare and important bridge in California that I was surprised I had not seen it come up in the news before. Its a bridge to watch closely, since in the future there may be an opportunity for pontists to voice support for any of the alternatives that involve preservation. I would hate to see this bridge demolished.
Nathan, thanks for keeping an eye on this bridge in the news.