FLH PDDM Chapter 9 - Eastern Federal Lands Highway Division

9.4.A. Geometric Design. (continued)a. Stopping Sight Distance. A roadway design requires minimum stopping sight distance at all points,and where economically justified more liberal stopping distances are desirable.Minimum stopping distance is the least distance required to bring a vehicle to a stop under prevailingvehicle and climatic conditions. It depends on the initial speed of the vehicle, the perception and reactiontime of the driver, and the coefficient of friction between tires and roadway for the prevailing conditions.The coefficient of friction is much lower for wet pavements; therefore, wet rather than dry pavementconditions apply for establishing minimum values.Design controls for SSD are in the Green book, pages 117 to 125, 219, 223, and 283 to 293. Also seeTables 9-4 and 9-5 in this chapter.9 - 27