Governor Phil Murphy • Lt. Governor Tahesha Way

Department of Transportation

Design Control For Radius of Horizontal Curve with Sight Obstruction

U.S. Customary English Units

See Roadway Design Manual Figure 4-A

This program calculates the Radius of a Horizontal Curve, using the measured Horizontal Sightline Offset (HSO) and required Stopping Sight Distance (S).

R = ((HSO)2+(S/2)2)/2HSO

Enter HSO and S
HSO = Horizontal Sightline Offset (ft.)
 S = See Table Below (ft.)
R = Radius (ft.) to the center line of the inside lane
Design Speed S = Sight Distance
Mph Stopping Distance Minimum
25 155
30 200
35 250
40 305
45 360
50 425
55 495
60 570
65 645
70 730


Last updated date: October 9, 2020 11:26 AM