You are working on a 1-km highway extension project that requires the construction of a 4-m tall soil embankment with a top width of 15-m and 2H:1V slopes. A borrow-pit (i.e., a place where soils are excavated, to then be placed elsewhere for construction projects) has been identified with e = 0.74, emax = 0.9, emin = 0.5. To avoid excessive road deformations, the soil will be compacted to a relative density of DR = 90% when placed in the embankment. Your boss estimates that extracting 100,000 m^3 of material from the borrow-pit should be enough for this project. Is your boss correct, or is more material than that needed? To decide, answer these questions: a) What volume of soil, as placed, is required to build the embankment? [Tip: draw the embankment] b) What is the void ratio of the material when placed in the embankment? c) What is the relative density of the material in the borrow-pit? d) When soil is extracted from the borrow-pit and then compacted it the embankment, how do…

There are 20 cars traveling at constant speeds on a 1 mile long ring track and the cars can pass each other freely. On the track 25% of the cars are traveling at 20 mph, 50% of the cars are traveling 10 mph, and the remaining 25% of the cars are traveling at an unknown speed. It was known that the space mean speed of all the cars on the track is 20 mph. (a) What is the speed that the remaining 25% of cars are traveling at? (b) If an observer standing on the side of the track counted the number and measured the speed of all cars that passed her for one hour, what is the time-mean speed of all the cars the observer counted? (c) What is the flow rate measured by the observer? (d) What is the car density on the track? Does density times space mean speed equal flow rate?

2.21 A small truck is to be driven down a 4% grade at 70 mi/h. The coefficient of road adhesion is 0.95, and it is known that the braking efficiency is 80% when the truck is empty and decreases by one percentage point for every 100 lb of cargo added. Ignoring aerodynamic resistance, if the driver wants the truck to be able to achieve a minimum theoretical stopping distance of 275 ft from the point of brake application, what is the maximum amount of cargo (in pounds) that can be carried?

An observer standing beside a one-lane road counted in 5 minutes 20 cars traveling at 30 mph, 30 cars traveling at 50 mph and 10 cars traveling at 60 mph. (a) What is the space and time-mean speeds of the observed cars? (b) What is the average headway of the cars? [

2.20 A driver is traveling at 90 mi/h down a 3% grade on good, wet pavement. An accident investigation team noted that braking skid marks started 410 ft before a parked car was hit at an estimated 45 mi/h. Ignoring air resistance, and using theoretical stopping distance, what was the braking efficiency of the car?

5.2 Assume that you are an observer standing at a point along a three-lane roadway. All vehicles in lane 1 are traveling at 30 mi/h, all vehicles in lane 2 are traveling at 45 mi/h, and all vehicles in lane 3 are traveling at 60 mi/h. There is also a constant spacing of 0.5 mile between vehicles. If you collect spot speed data for all vehicles as they cross your observation point, for 30 minutes, what will be the time-mean speed and space-mean speed for this traffic stream?

There are 20 cars traveling at constant speeds on a 1 mile long ring track and the cars can pass each other freely. On the track 25% of the cars are traveling at 20 mph, 50% of the cars are traveling 10 mph, and the remaining 25% of the cars are traveling at an unknown speed. It was known that the space mean speed of all the cars on the track is 20 mph. (a) What is the speed that the remaining 25% of cars are traveling at? (b) If an observer standing on the side of the track counted the number and measured the speed of all cars that passed her for one hour, what is the time-mean speed of all the cars the observer counted? (c) What is the flow rate measured by the observer? (d) What is the car density on the track? Does density times space mean speed equal flow rate?

e t a S t 1 d ? f a V f 1 2.20 A driver is traveling at 90 mi/h down a 3% grade on good, wet pavement. An accident investigation team noted that braking skid marks started 410 ft before a parked car was hit at an estimated 45 mi/h. Ignoring air resistance, and using theoretical stopping distance, what was the braking efficiency of the car? 2.21 A small truck is to be driven down a 4% grade at 70 mi/h. The coefficient of road adhesion is 0.95, and it is known that the braking efficiency is 80% when the truck is empty and decreases by one percentage point for every 100 lb of cargo added. Ignoring aerodynamic resistance, if the driver wants the truck to be able to achieve a minimum theoretical stopping distance of 275 ft from the point of brake application, what is the maximum amount of cargo (in pounds) that can be carried?

2.32 A driver is traveling at 52 mi/h on a wet road. An object is spotted on the road 415 ft ahead and the driver is able to come to a stop just before hitting the object. Assuming standard perception/reaction time and practical stopping distance, determine the grade of the road.