2 A temporary diversion has been constructed on a highway of

2) A temporary diversion has been constructed on a highway of-2% gradient. Determine the speed limit that should be imposed on the diversion if drivers can see the warning sign at a distance of 400 ft. The sign is located 75 ft from the diversion. The posted speed limit on the highway is 65 mph (4 points) Note: SSD = 1.47u1+ ul -u2 Where: SSD-stopping sight distance; u-design speed: G = grade of roadway (percent of grade/100)

Solution

Solution:-

Given

Initial speed (u₁) = 65 mph

Grade = 2 %

SSD = 400 + 75 = 475

Let t = 1.5 second

SSD = 1.47 ut + (u₁² – u₂²)/(30(.35 – G))

475= 1.47 * 65 *1.5 + ( 65² – u₂²)/(30*(.35 – 0.02))

u₂ = 30.68 mph Answer

Speed at time of diversion (u₂) = 30.68 mph Answer