Answer Happy

Question 4 20 pts Suppose an emergency turn around is designed as a horizontal curve with a radius of 300 ft based on the roadway centerline. The road has 1 lane, which is 14 feet wide, and no shoulders. trees are located 10 feet from the roadway (turn around) edge. The design speed is 20 mph. If standard values of reaction time and deceleration apply (you may use AASHTO tables provided): 1. What sight distance is required for safe operations at 20 mph? Report your answer to the nearest integer. feet 2. What is the value of the middle ordinate needed to provide adequate sight distance based on the tree location? Report your answer in feet to one decimal place. feet 3. Based on the distance of the trees from the roadway edge, what sight distance is available? Report your answer in feet to one decimal place. feet 4. Is this turn around reasonably safe? Type yes or no. Table 3-1. Stopping Sight Distance on Level Roadways Stopping Sight Metric Brake Braking Design Reaction Distance Speed Distance on Level (km/h) (m) U.S. Customary Brake Braking Reaction Distance Stopping Sight Distance Distance Design Speed Calculat- Design Calculat- Design Distance on Level (ft) (ft) (m) ed (m) (m) (mph) ed (ft) (ft) 20 13.9 4.6 18.5 20 15 55.1 21.6 76.7 80 30 20.9 10.3 31.2 35 20 73.5 38.4 111.9 115 40 27.8 18.4 46.2 50 25 91.9 60.0 151.9 155 50 34.8 28.7 63.5 65 30 110.3 86.4 196.7 200 60 41.7 41.3 83.0 85 35 128.6 117.6 246.2 250 70 48.7 56.2 104.9 105 40 147.0 153.6 300.6 305 80 55.6 73.4 129.0 130 45 165.4 194.4 359.8 360 90 62.6 92.9 155.5 160 50 183.8 240.0 423.8 425 100 69.5 114.7 184.2 185 55 202.1 290.3 492.4 495 110 76.5 138.8 215.3 220 60 220.5 345.5 566.0 570 120 83.4 165.2 248.6 250 65 238.9 405.5 644.4 645 130 90.4 193.8 284.2 285 70 257.3 470.3 727.6 730 75 275.6 539.9 815.5 820 80 294.0 614.3 908.3 910 Note: Brake reaction distance predicated on a time of 2.5 s; deceleration rate of 3.4 m/s² [11.2 ft/s²] used to determine calculated sight distance.