Daily Rules, Proposed Rules, and Notices of the Federal Government
The FHWA, in cooperation with Caltrans, will prepare an EIS on a proposal to seismically improve the 6th Street Viaduct in the city and county of Los Angeles, California. The proposed improvements would involve retrofitting or demolition and replacement of the existing viaduct over the Los Angeles River between Mateo and Mill Streets on the west side, and west of Interstate 5 on the east side, for a distance of approximately 0.9 miles.
The 6th Street Viaduct, built in 1932, is one of 12 historic bridges/viaducts crossing the Los Angeles River. The concrete elements of the 3,500 foot long 6th Street Viaduct are degraded by an ongoing chemical reaction, known as Alkali Silica Reaction (ASR), which has led to substantial deterioration of the structure and decrease of its concrete strength, rendering it vulnerable to collapse in a major earthquake. This ASR deterioration of the 6th Street Viaduct has been occurring for at least 75 years, despite ongoing efforts to arrest or limit its effect. While the deteriorated surface appearance of the viaduct is of concern, its underlying structural integrity is of much greater concern. In 1989, the Whittier Narrows earthquake caused damage to shear keys and caused a column crack at Bent 33 of the viaduct. The structure has since been classified by Caltrans as Category I and placed on the mandatory seismic retrofit list.
The proposed project would result in a structure capable of withstanding a moderate seismic event by either retrofitting the existing structure or replacing it entirely. Several alternatives were considered during the project development phase. Criteria used to identify alternatives to be carried forward for detailed analysis in the environmental document include construction and maintenance costs, life span of the facility, constructability, historic preservation, community disruption, and seismic and operational safety. Based on the results of public pre-scoping meetings and preliminary screening analysis, a No Build Alternative and two Build Alternatives, including Viaduct Retrofit and Viaduct Replacement, will be analyzed in the environmental document.
The project team has met with the general public and neighborhood groups, and a Community Advisory Committee has been actively engaged. Public information activities, including meetings with the project development team, will continue throughout the design and environmental process. Public and agency scoping meetings are scheduled on August 14th and 16th in Los Angeles. A subsequent public hearing on the draft EIS will be held to discuss alternatives and impacts of the proposed action. Public notices will be published and posted on the project Web site containing the specific time and place of the public scoping meetings and hearing. To ensure that the full range of issues related to this proposed action is addressed and all significant concerns are identified, comments and suggestions are invited from all interested parties. Comments or questions about this proposed action and the EIS should be directed to FHWA at the address provided above.