By Michael Raffety 5-6-13
Near the corner of our house just outside my Zen garden is an oak tree with a hollow in it. It has been home to nut hatches who set up a nest in it. But last year a new tenant took over the hollow space — wild honey bees.
Initially I was worried about the bees, but they haven’t bothered me when I am trimming shrubs in the area. They have done a fantastic job of pollinating my fruit trees, so I have grown to kind of appreciate them. Last summer I had so many plums growing on my Santa Rosa plum tree that I thought about selling them at the farmers market. I had fresh plums for weeks in my lunch. As it was about a dozen went unharvested.
My wife, who listens to NPR, told me the most fascinating story she heard about bees. Each flower has a very slight electrical charge that is detectable by bees. Once a bee enters a flower for its nectar it neutralizes the electrical charge. This informs other bees that the flower has already been used and they buzz along looking for the next opposite charge to neutralize. Who figures this stuff out? How do they measure positive and negative charges on bees and flowers? Information like that is just the bee’s knees.
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My last column generated two items of interest. One has to do with the artist featured at the newly located Museum of Craft and Design in San Francisco. The principal artist was sculptor Michael Cooper. The person truly surprised and impressed was Ken Deibert, who gathers and organizes the material for our “As We Were” column. Ken, who taught drafting at American River College, went through the master’s program at San Jose Sate University with Michael Cooper. Sometimes it’s just a serendipitous world.
The other item was one I ran across while filing our historical documents after moving into our new building. Last column I wrote about the LED light display on the Oakland Bay Bridge and added in some distance facts about the bridge. One of those factoids was that the tunnel through Yerba Buena Island is 540 feet long.
What I found was a letter from Earl Lee Kelly, director of the state Department of Public Works, to then Mountain Democrat Editor and Publisher Clarence E. Barker, dated Dec. 14, 1935: “I am enclosing herewith two pictures taken on our recent Bay Bridge inspection trip. I trust they will serve as a reminder of a very pleasant journey.”
The photograph is of a large group standing in front of the tunnel works for Yerba Buena Island. The bridge was completed in 1936 and opened for traffic on Nov. 12. Construction had begun in 1933. Three years! The new eastern span replacement began construction in 2002 and is due to open by Labor Day this year. Problems with huge bolts on seismic anchor shear keys have the potential to put off opening the bridge until sometime in 2014.
According to the official Website for the $6.4 billion Bay Bridge construction project, 32 out of 96 bolts cracked while being stressed. There are two fixes to hold the shear keys in place — a steel collar or a steel saddle. The selection will be made May 8.
The bolts can’t be replaced. The 288 bolts range in length from 9 to 24 feet. When they started tightening 96 to connect the shear keys to the caps, 32 broke.
How this system works in case of an earthquake is best described by the official Website: “The eastern foundation of the self-anchored suspension span contains seismic devices called bearings and shear keys. The bearings allow the road-decks to move slightly during a seismic event, while the shear keys prevent the decks from moving too much. The four bearings (two beneath each deck) and four shear keys (one beneath each deck and two beneath the cross beam connecting the decks) are bolted between the roadways and a concrete cap beam with steel anchor rods.”
It’s the 96 manufactured in 2008 that are problematic.
Some newspapers have pegged the engineering fix at about $1 million.
The self-anchored tower holding up the suspension cables is 525 high. The new east span is 2,047 feet long. The new skyway approach is 1.2 miles long.
The new eastern span is supposed to replace the truss structure where the roadway buckled in several spots and dumped some cars into the bay during the 6.9 magnitude Loma Prieta earthquake in 1989. So we’ll put our faith in the engineers to make the new span safe and earthquake resistant.