The term "fast track" is used in the design and construction industry to mean a project whose construction is started before the final designs are complete. They may still be working out the electrical system while the foundations are being poured and track is being layed. They can do this because wiring, hydraulics, and other systems aren't critical to the intial phase of coaster construction. I've worked on several projects where we didn't have the interior partitioning designed until 3 months before projet completeion.
--seth