Sunday, June 24, 2012

We now sit less than a week from finishing the bridge, a point which has taken a considerable amount of sweat and effort to get to. This past week was likely the most brutal week physically, as we had to pour concrete or rapidly build masonry every day until Friday. At almost 6 cubic meters each, our anchors are about twice the size of typical B2P anchors, and the design also calls for 1.9 meter high masonry dead weights about those anchors to prevent the anchor from uplifting. All told, that adds up to 36 cubic meters which we had to pour (To give you an idea, one cubic meter of concrete required us to use around 11 bags of cement, each weighing 90 pounds, 55 buckets of gravel, each weighing enough to make your shoulders really sore, and 33 buckets of sand). We were able to use formwork to speed the process of building the dead weights, and had a gas powered mixer, but it was a laborious process.

Above is an overview shot of the whole process--the only breaks for the people shovelling and tossing ingredients into the mixer came in the five minute intervals in which we added rock layers. The cable sag was set on Friday. We thought this would be harder than it was (but also quicker). Because our sag is much lower than the typical B2P design (3.50% versus 5%), the cables had to be pulled to nearly horizontal in order to set them in the right place. This step is the only very dangerous step, as the winch and the cable it is attached to are under very high tension. Luckily, there were no incidents.

Above, Maria takes out some anger on the cables (actually whacking it with a stick is a proper way to fine-tune the sag). Below, Steve completing the first crossing of the bridge. Unfortunately, Steve had to leave (and should be airborne as of this post), but we did get to within a day or two of a completely usable bridge--although ours is currently completely usable for any tightrope walkers in the San Francisco area).

On Thursday, we went to the community leader's house (which also serves as San Francisco's elementary school, serving 20 students) for dinner, and after took a walking tour of San Francisco. It was amazing that seemingly every household we passed had several people who are regularly volunteering their time to work on the bridge. We also got to travel a bit this weekend, and while in Managua to see Steve off, we all got to go to Masaya, to both its artisan markets and its active volcano, Granada, a colonial city founded in 1524, and Lake Nicaragua, a huge expanse which contains several volcanoes in addition to its freshwater sharks.

Above is a picture of a friend who came to help us out at the bridge site one day. Unfortunately, he passed away shortly thereafter. Below, a picture of our most recent progress. Can't wait to show pictures after another week!

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