BarstowRick has a RailImages album that gives some narrative and photographs of various curve radii and how various lengths of cars will appear on them. While this is N scale, the various radii can be extrapolated to H0 scale by multiplying by a factor of 1.83. Thanks to BarstowRick for this informative and innovative presentation. This thread is a discussion of the photos. Here is one photo fron the series: Additional search terms: track radius switch turnout Peco Atlas Kato ME unitrack