There is no way the track expanded that much, probably no more than 1/64" (http://www.engineeringtoolbox.com/thermal-expansion-metals-d_859.html). If you have very low humidity, then the wood may have shrunk that much, although it wouldn't take 1/2" of difference to be able to slide a pencil underneath the track. Take a piece of paper and lay it out flat, then see how little you have to push the ends together to be able to slide a pencil underneath.
Switch to On30. that's what I did. It breathed new life into my interest in the hobby. There are a lot of former N Scalers in On30.
I've got a climate-controlled basement room and still have problems with humidity ranges. In the winter it will get very dry with the furnace running, and in the summer I have to run a dehumidifier to keep it under control. Even with every last inch of the benchwork painted (which slows it down anyway) I'll still see annual gaps opening at the module joints and at the joints in the backdrop. It will all close up again in the fall. That's with temperature pretty constant and only humidity variability (and monitored with gauges), and over no more than 8' I'll see about 1/16"-3/32". On my previous N layout that had sun exposure I had sun kinks in the summer on C80 flex, when ballasted down it would kink on the curves and narrow the gauge at the rails, but never actually broke loose. "Slinky" Atlas C80 is a lot more subject to gauge variance due to heat. Our company 'display' HO layout in a storefront window with sun exposure takes a complete beating as it is exposed to wide variation in humidity and temperature. I've had sun kinks bad enough to derail a train - and that's Atlas C100 snap-track, ballasted in place. You can do a lot to design for it, but you sure can't ignore it. Sooner or later a layout will experience that kind of heat/humidity variance, even if only during transport. My portable modules that are no longer than 4' get hot summer car trips to shows and it happens there too. That's one of several reasons why I chose Peco C55, it will still expand, but it's not going to break the actual track - it will tear off the roadbed first at the curves or just expand out the ends.
He's not doubting how much it expanded. But a 30" piece of flex by itself only need 1/64"-1/32" of expansion or wood retraction to buckle as much as what you show in that picture. If you don't have enough expansion gaps and have rail runs longer than 30", even the most minimal expansion will cause what you're seeing. Jason
