Curved turnouts - at least the Walters/Shinohara and Peco seem to have no more trouble than regular turnouts. And they can save considerable space in tight situations. I would much prefer to use curved turnouts than drop my minimum radius below 18 inches.
Less than 18 inches will likely be trouble on your turntable approach tracks. Larger steam locomotives and 6 axle diesels often (but not always) have trouble with 18" radius curves, much less anything tighter. Again, I would sacrifice a turntable approach track or roundhouse stall rather than tighten radius there.
In the yard, a 15" radius will work with 40ft and shorter freight cars - but you cannot couple or uncouple on such sharp curves. Longer freight and passenger cars will not take kindly to less than 18" radius either. Rule of thumb is that 15/16" radius is pretty much limited to switching locomotives and 40ft or less freight cars in HO.
Another way to help yourself is to cut back the turnouts. Almost all commercial turnouts have extra track beyond the frog, and in front of the points. This can usually be cut back almost to the frog or points where/when needed without serious consequences.
yours in tracking
Less than 18 inches will likely be trouble on your turntable approach tracks. Larger steam locomotives and 6 axle diesels often (but not always) have trouble with 18" radius curves, much less anything tighter. Again, I would sacrifice a turntable approach track or roundhouse stall rather than tighten radius there.
In the yard, a 15" radius will work with 40ft and shorter freight cars - but you cannot couple or uncouple on such sharp curves. Longer freight and passenger cars will not take kindly to less than 18" radius either. Rule of thumb is that 15/16" radius is pretty much limited to switching locomotives and 40ft or less freight cars in HO.
Another way to help yourself is to cut back the turnouts. Almost all commercial turnouts have extra track beyond the frog, and in front of the points. This can usually be cut back almost to the frog or points where/when needed without serious consequences.
yours in tracking