The patience of motorists who daily drive the patched-up Pacific Coast Highway between Malibu and Santa Monica was put to the test again. A monumental morning commuter tie-up was triggered by work on a broken water pipe. According to the California Department of Transportation, the water pipe broke last Monday about 100 feet south of Sunset Boulevard, adjacent to the heavily traveled PCH's southbound lanes. Caltrans crews had been working on the break on off-commuter hours so as not to disrupt traffic patterns, the spokeswoman added. But on Wednesday night, she said, Caltrans decided to work all night and into the Thursday Santa Monica-bound morning commuter period, thus closing PCH's curb lane to commuter traffic and causing a massive backup of several miles to Las Flores Canyon Road in Malibu. "We had a lot of calls this morning" from irate motorists who were undoubtedly late for work since it took about an hour to negotiate what ordinarily would take a few minutes, the spokeswoman said. Caltrans officials promised to have the job completed by Friday evening. A Caltrans supervisor later attributed the traffic jam to the fact that motorists weren't reading the traffic cones correctly and weren't using an extra lane that was available.