A federal loan guarantee authorized for the Alaska gas pipeline is intended to help smooth the path forward for what could be the world's most expensive private project ever. The guarantee joins other measures in federal law designed to ease the project ahead and lower its capital costs. The other measures include putting a key regulator on a timetable to act, accelerating the pipeline depreciation for tax savings, restricting court challenges of the project, and allowing tax credits for a massive gas treatment plant at Prudhoe Bay.