NEW YORK - Proposed high-speed rail lines in the western United States moved a step closer to reality Tuesday with the announcement of $6 billion in government grants. The cash will come from President Joe Biden’s signature infrastructure bill aimed at revamping the country’s creaking railways, roads and bridges, and is part of a plan to double the number of people taking the train by 2040. Half of the cash will go towards the construction of a high-speed line spanning 218 miles (350 kilometers) between Las Vegas and downtown Los Angeles, slashing the current five-hour car journey time to two-hours and 40 minutes. The rest will be used to support a long-touted line linking Los Angeles with San Francisco. While high-speed rail is the norm in much of Europe and Asia, particularly in China and Japan, the United States has long lagged behind.