Please write legible and do not skip steps. A road with a 4.2% grade has a stopp
ID: 1866585 • Letter: P
Question
Please write legible and do not skip steps. A road with a 4.2% grade has a stopping sight distance of 300 feet. Assuming a PRT of deceleration rate of 11.2 ftis2, The design speed of the road is most nearly o A 30 mph o B-25 mph QUESTION 7 ? 55 mph ?D40 mph 5 p QUESTION 8 At an intersection, drivers can see 250 feet to the left and 300 feet to the right. If tg 6 5 seconds for right turns and tg-75 seconds for left turns, which is most nearly the maximum design speed of the cross street to maintain intersection sight distance? e A 20 mph o8 30 mph o C 25 mph o D. 35 mph QUESTION S A fexible pavement system comprised of Hot Max Asphalt and an aggregate base has a structural number of 75. Given the following information, the depth in inches of the HMA is most nearly Layer Layer Coefficient (a) Depth (in) Hot Mix Asphalt (HMA) 052 Aggregate Base 10 in 12in 16 in 0.13 18 B.Explanation / Answer
7)
SSD=300 feet
gradient=4.2%
t=2.5sec
a=11.2ft/sec2
SSD=1.47Vt+V2/30(a/g-G)
300=1.47xV(2.5)+V2/30(11.2/32.2-0.042)
0.108V2+3.675V-300=0
V2+34.02V-2777.77=0
V=38.37 mph, other one is negative so not considered
V=40 mph (approximately)
8)
250 feet to the left
300 feet to the right
Tg=6.5 seconds (right)
Tg=7.5 seconds (left)
d=1.47Vt
250=1.47XVx7.5
V=22.67 m.p.h
d=1.47XVXt
300=1.47xVx6.5
V=31.3 p.p.h
Consider the lower speed which is approximately 20 mph
9)
SN=a1d1+a2d2
7.5=0.52(d1)+0.13(18)
d1=9.92 in
which is approximately 10 in