Question

9:381 LTE Problem 1 A crest vertical curve is to be designed to join a +2% grade with a-2% at a section of a two-lane highway. Determine the minimum length of the curve if the design speed of the highway is 60 mph and SL. Assume that a-9.34 ftsec' and that the perception-reaction time is 2.5 sec. Problem2 A crest vertical curve is to be designed to join a +3% grade with a-2% grade at a section of a two-lane highway. Determine the minimum length of the curve if the design speed of the highway is 60 mph, ScL and a perception-reaction time of 2.5 sec. The deceleration rate from braking (a) is 11.2 ft sec Problem 3 An existing vertical curve on a highway joins a +4.4% grade with a .44% grade. If the length of the curve is 275 ft.. what is the maximum safe speed on this curve? What speed should be posted if 5 mph increments are used? Assume a-11.2 ftisec perception-reaction time 2.5 see, and SL Problem A sag vertical curve is to be designed to join a .5% to a .296 grade. If the design speed is 40 mph, determine the minimum length of the curve that will satisfy all criteria. Assume a-11.2 ftsee and a perception-reaction time of 2.5 sec Problem5 A crest vertical curve joining a +3% and a-4% grade is to be designed for 75 mph. If the tangents intersect at station 345+00 at an elevation of 250 ft, determine the stations and clevations of the BVC and EVC. Also calculate the elevation on the curve at stations 340+00 and 352+00. Problem 6 A sag vertical curve joins a-3% grade and a +3% grade. If the PVI of the grades is at Sta. 435+50 and has an elevation of 235 ft, determine the station of the BVC and EVC for a design speed of 70 mph. Also, compute the elevation of the curve at 432-00 and 438+00 Problem7 Two semi-trailers are traveling down a 5.5% grade at 40 mph on a two-lane highway in the same lane. Truck A has new tires Truck B has worn tires. The roadway is paved with Portland cement concrete. Driver A suddenly slams on the brakes to make a panic stop. Assume it takes Driver B 1.5 see. to react to Driver A. Friction factors for new tires-0.76; won tires-0.33 What is the new distance between trucks A and B? Problem 8 A-4.3% grade intersects a +3.7% grade at Sta. 50-00 and clevation 532 20 ft. The top of the culvert clevation at Sta 50+00 is $40.00 ft. Six feet of clearance is required. What minimum of length of vertical curve will provide for necessary cover?

Answer 1