Double-Decking the Freeways

by James F. Roberts, (F.ASCE), Chief; Division of Structures, Caltrans, Sacramento, CA,

Serial Information: Civil Engineering—ASCE, 1991, Vol. 61, Issue 11, Pg. 48-50

Document Type: Feature article


Elevated highways cost more than at-grade construction. Nonetheless, the hidden costs of increased traffic congestion and the real cost of urban right-of-way make elevated highways feasible. California is one of several states planning and constructing such highways, known coloquially as double-deckers. Studies in that state show a drastic need for additional lanes, some of which will be devoted HOV's or designed for future light-rail use. The design and construction of one project in Los Angeles, the 1-100 HOV viaduct, is decribed. The contractor made an alternative construction proposal for constructing the elevated portion in two-span segments, partially stressing those segments and moving the erection bridge and then stressing four segments together. Construction was done largely in the median during commuter traffic, and partially at night. The project was completed on time, with few problems. Techniques refined at the site will be used elsewhere in the state.

Subject Headings: Infrastructure construction | Decks | Highways and roads | Traffic congestion | Bridge design | Project management | Night time construction | Construction costs | California | United States | Los Angeles

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