Many people on the big Island are bracing for major upheaval if lava from Mauna Loa slides across a key highway and blocks the quickest route connection two sides of the island. The molten rock could make the road impassable and force drivers to find alternate coastal routes in the north and south. This could add hours to commute times. The lava is oozing slowly at a rate that might reach the road this week, but its path is unpredictable and could change course, or the flow could stop completely and spare the highway.