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? (Mannering 53) Mannering, Fred L., Scott Washburn. Principles of Highway Engineering and Traffic, 6th Edition. Wiley, 2016-09-15. VitalBook file. The citation provided is a guideline. Please check each citation for accuracy before use. (Ans: 88%; Hint for frl, use average speed)

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? (Mannering 53) Mannering, Fred L., Scott Washburn. Principles of Highway Engineering and Traffic, 6th Edition. Wiley, 2016-09-15. VitalBook file. The citation provided is a guideline. Please check each citation for accuracy before use. (Ans: 88%; Hint for frl, use average speed)

Traffic and Highway Engineering

5th Edition

ISBN:9781305156241

Author:Garber, Nicholas J.

Publisher:Garber, Nicholas J.

Chapter3: Characteristics Of The Driver, The Pedestrian, The Bicyclist, The Vehicle, and The Road

Section: Chapter Questions

Problem 25P

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A car is traveling at 76 mi/hr down a 3% grade on poor, wet pavement. The car's braking efficiency is 90%. The brakes were applied 320 ft before impacting an object. The car had an antilock braking system, but the system failed 200ft after the brakes had been applied (wheels locked). What speed was the car traveling at just before it impacted the object? (Assume theoretical stopping distance, ignore air resistance, and let Frl=0.015)
A car is traveling up a 3% grade, with the speed of 85mph, on a road that has good, wet pavement. A deer jumps out onto the road and the driver applies the brakes 290-ft from it. The driver hits the deer at a speed of 20mph.If the driver did not have antilock brakes, and the wheels were locked the entire distance, would a deer-impact speed of 20mph be possible? (Hint: check the braking efficiency) [Use Theoretical Stopping Distance]
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A car traveling at 45 mph on a poor, wet pavement has a braking efficiency of 87%. The brakes were applied 100 feet before hitting an obstacle in the road. The road is uphill for 40 feet and then is level for the remainder of the way. The car had a maximum coefficient of road adhesion in the sloped portion of the poor, wet roadway and but as soon as it started going on the level portion its coefficient of road adhesion reduced to 0.3. Assuming that the car struck the obstacle at 30 mph, what was the grade of the hill? Assume practical stopping distance equation applies.
Problem 2. A car hits a tree at an estimated speed of 25 mph on a 3 % upgrade. If skid marks of 120 ft are observed on dry pavement (coefficient of braking friction, fb =0.35) followed by 250 ft (fb =0.25) on a grass stabilized shoulder, estimate the initial speed of the vehicle just before the pavement skid began.
A car is traveling at 70 mi/h on a level section of road with good, wet pavement. Its antilock braking system (ABS) only starts to work after the brakes have been locked for 100 ft. If the driver holds the brake pedal down completely, immediately locking the wheels, and keeps the pedal down during the entire process, how many feet will it take the car to stop from the point of initial brake application? (The braking efficiency is 80% with the ABS not working and 100 % with the ABS working. Use theoretical stopping distance and ignore air resistance. Let frl = 0.02 when the brakes are locked, but complete the frl once the ABS becomes active.)
The driver of a vehicle saw a stray dog 40 meters away and decided to hit the brakes instantaneously. If the distance of the vehicle from the dog is 15 meters after the vehicle had stopped, what is the average skid resistance of the pavement if the vehicle is travelling at a speed of 65 kph?
a vehicle was stopped in 2.1 seconds by fully jamming the brakes and the skid mark measured 10 meters. Determine the average skid resistance on the level pavement surface.
Q1) Choose the correct answer.. 1-The first stage in traffic engineering studies is.. A. Traffic volume studies B. Spot speed studies C. Speed and delay studies D. Origin and destination studies 2.For the movement of vehicles at an intersection of two roads, without any interference, the type of grade separator generally preferred to, is A. Partial Cloverleaf B. Trumpet C. Diamond Interchange D. Full Cloverleaf 3. Pick up the incorrect statement from the following.. A. The speed on urban roads 120-130 km/hr. B. There is no control on the urban roads Access. C. The urban roads are use for long distance. D. Level of service for urban roads A and B. 4. The main objective of traffic volume studies.. A. To decide priority for improvement of roads. B. For geometric design. C. For computing roadway capacity. D. To plan traffic operation. 5. The minimum space headway increases with A. Increase in length of vehicle. B. Increase in width of vehicle. C. Increase in weight of vehicle. D. Increase…
A car is driving at 75 mph down a 4.0 % grade on poor, wet pavement. The car's braking efficiency is 90%. The driver saw an object which is 480 ft away and applied the brake, and his reaction time was 1.0 second. The car's antilock braking system (ABS) works. Just after seeing the object, which of the following is closest to the distance (in ft) traveled before applying the brake? (Assume theoretical stopping distance ignore air resistance and let yb= 1.04 and fr = 0.015). 153 ft B) 127 ft 135 ft