State Route 710, a freeway heavily used by commuters and trucks hauling goods from the nation’s busiest port complex, runs 23 miles from Long Beach to an abrupt end just east of Los Angeles. From there, tens of thousands of vehicles a day spill onto Alhambra city streets to reach other freeways. The 4 1/2-mile gap between the end of the 710 and Interstate 210 in Pasadena is a startling deviation from the rule that freeways are king in California.