ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.
Issue link: http://www.aspiremagazinebyengineers.com/i/306186
When the city of Redding, Calif., decided to replace two existing, parallel crossings of the Sacramento River in Shasta County, creative engineering solutions and uniquely aesthetic design elements became key priorities for the new iconic bridge that would serve as a gateway to the city. Cypress Avenue is a highly travelled link between Redding and busy I-5. The existing steel girder bridges, built in 1948 and 1968, did not meet traffic demands, pedestrian access width, vertical clearance, foundation scour, and seismic design requirements. River Environment The Sacramento River is a major w a t e r w a y m e a n d e r i n g 3 8 0 m i l e s through Northern California from its origin near Mount Shasta to its terminus in San Francisco Bay. The bridge crossing location is near the source of the river, which is an area of sensitive habitat for Chinook salmon and steelhead fish species. This section of the river is also used extensively for recreational fishing and boating, as well as nature hikes, and plays a crucial role in the expansion of a hiking trail and riverfront park. Project improvements needed to consider impacts on these natural and recreational resources. The Cypress Avenue Bridge replaced the two existing bridges with a six- lane signature bridge, including a bike lane and sidewalk on both sides in compliance with city plans for the Cypress Avenue corridor. In addition to the bridge, the project also included significant widening of approach roadways, construction of conventional re t a i n i n g w a l l s , m o d i f i c a t i o n o f t w o a d j a c e n t i n t e r s e c t i o n s , a n d reconstruction and realignment of adjacent connnector roads. Replacement Structure In order to maintain four lanes of traffic throughout construction, the existing bridges were replaced in three stages, with each stage requiring approximately 1 year. To accommodate the construction stages, the superstructure consists of three parallel box girders. Two of the girders have three cells and one has four. A 3-ft 6-in.-wide closure placement was used between each of the construction stages. The six-lane replacement structure consists of a 1025-ft-long, 119-ft 6-in.-wide, five-span, haunched, cast- in-place, post-tensioned concrete box-girder bridge on a 9997-ft-radius curved alignment. The span lengths are 180, 200, 230, 230, and 185 ft. The vertical profile over the river includes an 800-ft-long, – 0.25% vertical curve with no superelevation. The deck area provides 9-ft 9-in.-wide areas on each side for sidewalks, lighting, railings, and barriers. There are 8-ft-wide exterior shoulders plus six, 12-ft-wide travel lanes. A 12-ft-wide central area accomodates interior shoulders, a median, and additional lighting. The haunched box girder depth varies from 8 ft 9 in. at midspan to 14 ft. 9 profile CYPRESS AVENuE BRIDGE / REDDING, CALIFORNIA BRIDGE DESIGN ENGINEER: T.y. Lin International, Sacramento, Calif. PRojECT ARCHITECTS: T.y. Lin International and MacDonald Architects, San Francisco, Calif. PRIME CoNTRACToR: Kiewit, Fairfield, Calif. LIGHTING AND ILLuMINATIoN: Illumination Arts LLC, Bloomfield, N.J. by Michael Fitzpatrick and Chris Hodge, T.y. Lin International by Michael Fitzpatrick and Chris Hodge, T.Y. Lin International by Michael Fitzpatrick and Chris Hodge, T.Y. Lin International by Michael Fitzpatrick and Chris Hodge, T.Y. Lin International Cypress Avenue Bridge Replacement Project Redefining the Road to Redding, California Typical bridge pier with lanterns and overlooks. Photo: C. Hodge, T.y. Lin International. 36 | ASPIRE , Summer 2011 Book_Sum11.indb 36 7/1/11 10:00 AM