California’s High Speed Rail Authority is reconsidering plans for a new leg, which would run from Los Angeles to San Diego, of a $42-billion, 800-mile system; instead, it now is weighing a shared-track arrangement with Amtrak. The proposal was put forth on April 8 by Richard Katz, an authority board member. He says that the measure could save an estimated $2 billion and would eliminate the need to demolish hundreds of homes and businesses. The project has been awarded $2.25 billion in federal stimulus funding and could begin construction as early as fall 2012.