Name/Title
Print, PhotographicEntry/Object ID
2012.16.26Description
Photo of laborers working on the "ribs" of the covered conduit section of the aqueduct in the Mojave Desert. There is an early automobile in the background.
Complete Report on Construction of the Los Angeles Aqueduct, 1916, page 174: "The first few miles of conduit were built with a concrete roof that was tied into transverse ribs on top of the cover. These ribs were 3 feet apart, center to center, with a maximum height of 15 inches in the center, and 5 3/8 inches thick. The roof slab proper was but 3 inches thick, reinforced with wire mesh. After casting, the slab itself was covered with earth and the rib with sacks, all of which were wet down with a hose. It was found that while the earth could be kept moist, the sacks would dry out in a few minutes and the rib would cure at a different rate from the slab. This inharmonious curing of the rib and the slab had a tendency to produce shrinkage cracks at the connection between the rib and the slab, and largely for this reason the type of cover was changed and a flat slab substituted, which was 6 inches thick on the sides and 7 inches in the center. The same amount of reinforcing was put into this flat slab as was used in the ribbed cover, and a slightly greater quantity of concrete."Collection
Albert Ross Collection