How large?

Full size, a 22 degree curve is equivalent to 514 foot radius (approx).

In HO, about 71" radius and N, about 38"

I'd guess that you need 16 pieces of 22 degree curved track sections to make a circle. The radius or diameter apparently isn't mentioned.

Regards, Greg.P.

Reminds me of the road signs showing a traffic island (roundabout) that show it as a "C" (instead of an "O"). Presumably to mean you can't, or shouldn't, go round the complete circle.

Not if you own a hammer or 16 pieces of 0.5 degrees track sections! =8^)

I'd tend to try it just to check the accuracy of their signage!

Regards, Greg.P.

Greg, in N. America, the "degree" of a curve refers to its curvature. It's the angle subtended by a 100ft tangent - makes laying out a curve very easy. The higher the degree, the tighter the radius.

Trivia: At one time, CPR had a 23 degree curve at Boston Bar, BC. It was the tightest mainline standard gauge curve in N. America, and for all I know in the world.

The 22 degrees refers to the degree of curvature, defined (at least in the US) as the degrees of arc of a circlular curve that would intersect the ends of a chord of 100 feet (a "chain" - a surveyor's tool). European track surveyors use a similar approach, but the chain is a metric unit.

It does not refer to the degrees of arc of piece of sectional track. See the site below for an explanation and a formula to convert degrees of curvature:

Sure, but the questioner didn't give enough information for you to conclude what it was he really wanted to know.

I believe it's a 100 ft. chord, not a tangent.

Correct.

To get the radius of a full size curve, divide 5730 by the Degrees of Curvature. For model railway use, divide this value by the appropriate scale. The reference that I got this info. from, and which I cannot remember the name of, said that the one hundred feet chord is used on railway layout, but for road design, an arc of one hundred feet is used, which sounds less convenient than a chord measurement. Regards, Bill.