U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
Diagram of an east/west roadway with a curve that causes it to be come a north-northwest/south-southeast roadway. The curve is divided into thirds by length, with the second third of the curve depicting the partial deflection angle comprised of two straight lines that intersect at an angle of about 60 degrees.
Two vehicles are drawn on the roadway in the area of the curve, one behind the other as they appear to navigate the curve. Both vehicles are circled. The circles have arrows extending to two compasses. The leading vehicle's compass is labeled Compass Heading 2 and the following vehicle's compass is labeled Compass Heading 1. Each compass is a circle with an arrow mounted in the center of the circle and the 90, 180, and 270 degree marks labeled.
Compass Heading 1 depicts an angle of about 100 degrees, and compass heading 2 depicts a heading of about 160 degrees.
A label on the diagram reads as follows:
Partial deflection angle = Compass heading 2 - (minus) Compass heading 1
Partial deflection angle = 160 minus 100
Partial deflection angle = 60 degrees.