EARTHQUAKE / LIFELINES OF L.A. : 10 Riskiest Bridges

These are 10 freeway bridges that Caltrans has ranked as the most seismically hazardous in Los Angeles County. Retrofitting work has has been completed on four. These 10 bridges are among 716 throughout the county that have been designated for strengthening and ranked by Caltrans in order of their risk. All cost figures are estimates.

* BRIDGES: Junction of Ventura Freeway (California 134) and Golden State Freeway (I-5). Cost: $5.8 million to retrofit bridge and high crossing over the Los Angeles River. Status: Design work began January, 1992, and is completed. Next step is to advertise for construction bids.

* BRIDGES: Junction of San Diego Freeway (I-405) and Santa Monica Freeway (I-10). Cost: $2.7 million for work on northeast and northwest connector overcrossings. Status: Design work began in August, 1989; construction completed in November, 1991.

* BRIDGE: Robertson/National undercrossing on the Santa Monica Freeway. Cost: $1.6 million. Status: Design work began May, 1991, and is completed. Next step is to advertise for construction bids.

* BRIDGE: Junction of Golden State Freeway and Los Angeles River, just north of the Pasadena Freeway. Cost: $900,000 Status: Design work began February, 1991; construction completed July, 1993.

* BRIDGES: Junction of Ventura Freeway and Hollywood Freeway (U.S. 101 and California 170). Cost: Almost $2 million for work on two bridges. Status: Design work began in May, 1991; completed last year. Construction bids now being solicited.

* BRIDGE: Centinela/Pico undercrossing on Santa Monica Freeway. Cost: $1.5 million Status: Design work began March, 1991; construction virtually complete.

* BRIDGE: Junction of Tujunga Wash and Ventura Freeway (U.S. 101). Cost: $766,000. Status: Design work began in July, 1991. Construction bids now being solicited.