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The James E. Roberts Memorial Bridge is a 1,400 foot two-lane highway bridge on California State Highway 120, in Tuolumne County, California. The bridge spans the Tuolumne River just north of Lake Don Pedro, near the community of Chinese Camp. It opened in 1971. Originally named the Tuolumne River Bridge, it was renamed in 2007 in honor of James E. Roberts by legislative resolution.〔(Res. Chapter 83, Statutes of 2007)〕 Roberts was the California Department of Highways (now, Caltrans) project manager, his first project management assignment as a senior bridge engineer. The cost to create new highway signs was raised by private donations. ==Designers== Key members of the Tuolumne River Bridge project, in addition to Mr. Roberts, were Richard "Dick" Dokken, PE, as lead design engineer; M. Comacho, PE, as details and quantities engineer, George Amaro, PE, as specifications engineer; and R. J LeBeau, PE, and K. C. Blechinger, PE, as independent design checkers. Herbert K. Jensen, PE, was Resident Engineer for Bridge Construction, and John F. Harrington, PE, was assistant resident engineer. This bridge, located north of Yosemite, was necessitated by a new highway alignment the resulted from creation of the new Don Pedro Dam reservoir. James Roberts laid out the bridge on a horizontal curve with a 1,200 foot radius curve to meet the requests of the highway engineers. Large bridges of this size were normally built straight, and California bridges required a detailed seismic analysis. Normal weight concrete was used for foundations or bridge piers and lightweight concrete was used for the bridge deck. The superstructure was painted steel curved girders trucked into the site. The bridge had to be completed prior to the filling of the reservoir. The tallest column is about 230 feet high, so falsework for concrete superstructure was not practicable. The highway engineers requested that the bridge have a capability to be widened from 2-lanes of traffic to 4-lanes, as planning at the time assumed that a wider highway would be necessary by 1995. The columns and foundation system were thus designed to support a second superstructure. The highway and bridge remain at two lanes wide today. As the majority of the north south freeway traffic is on I-5 or Highway in the relatively flat farming valleys. Highway 49 is a winding, scenic highway that follows the profile of the foothills to the Sierra Nevada Mountain range. The top 70 feet of the bridge columns have an equilateral triangular shape to support the four lanes of proposed superstructure. The initial 2-lanes were placed on the outside radius, so eccentric loading analysis of the columns was necessary. The foundation was excavated rock and is essentially hexagonal in shape to stabilize the column. The column is reasonably complicated and attractive. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「James E. Roberts Bridge」の詳細全文を読む スポンサード リンク
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