A driver traveling down a 4% grade collides with a roadside object in rainy conditions, and is issued a ticket for driving too fast for conditions. The posted speed limit is 65 mi/h. The accident investigation team determined the following: The vehicle was traveling 40 mi/h when it struck the object, braking skid marks started 205 ft before the struck object, the pavement is in good condition, and the braking efficiency of the vehicle was 93%. Using theoretical stopping distance, assuming aerodynamic resistance is negligible, and with the coefficient rolling resistance approximated as 0.015, should the driver appeal the ticket? Why or why not?

A driver traveling down a 4% grade collides with a roadside object in rainy conditions, and is issued a ticket for driving too fast for conditions. The posted speed limit is 65 mi/h. The accident investigation team determined the following: The vehicle was traveling 40 mi/h when it struck the object, braking skid marks started 205 ft before the struck object, the pavement is in good condition, and the braking efficiency of the vehicle was 93%. Using theoretical stopping distance, assuming aerodynamic resistance is negligible, and with the coefficient rolling resistance approximated as 0.015, should the driver appeal the ticket? Why or why not?

Traffic and Highway Engineering

5th Edition

ISBN:9781305156241

Author:Garber, Nicholas J.

Publisher:Garber, Nicholas J.

Chapter6: Fundamental Principles Of Traffic Flow

Section: Chapter Questions

Problem 9P

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part a, assuming decelerat on rate is unknown bu the friction factor=0.2. 2. A driver traveling down a 4% grade collides with a roadside object. The roadway has a posted speed limit is 60mph. The driver mentioned he strictly followed the speed limit. The accident investigation team indicates: braking skid marks started 300 ft before the struck object. a. If the friction factor was measured as 0.2, estimate the speed of the vehicle when it struck the object. b. Estimate the minimum required friction factor so the 300 ft skid marks can allow the driver to safely stop before he would strike the object.
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, a. If the car’s antilock braking system was effective (no sliding wheels on the pavement), what would the crash speed be?
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? If the car’s antilock-braking system was effective (no sliding wheels on the pavement), what would the crash speed be?
A vehicle hit a big tree near the edge of highway pavement. Based on the conditions of damages on the vehicle, the estimated speed when the vehicle hit the tree was 20 mile/hr. The observed skid mark on the pavement was 350 ft. The grade of the highway is 3% downward and F=0.35. What is the initial speed of the vehicle right before the driver pushed the brake ?
II. A student trying to test the braking ability of her car determined that she needed 19.5 ft more to stop her car when driving downhill on a road segment of 5% grade than when driving downhill at the same speed along another segment of 3.5% grade. Determine the speed at which the student conducted her test and the braking distance on the 5% grade if the student is traveling at the test speed in the uphill direction. - 30 points
A car is approaching toward an intersection with speed 45 mph. The road has a downhill grade of 1%. When the car is at a distance of 250 ft from the intersection, the signal turned yellow. If the driver applies brake and the reaction time of the driver is 1.5 s, will the driver be able to come to a complete stop? Justify your answer with calculations. Assume braking friction coefficient of 0.35.
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 student trying to test the braking ability of her car determined that she needed 19.5 ft more to stop her car when driving downhill on a road segment of 5% grade than when driving downhill at the same speed along another segment of 3.5% grade. Determine the speed at which the student conducted her test and the braking distance on the 5% grade if the student is traveling at the test speed in the uphill direction.
QUESTION 2 An intersection has a speed limit of 35 mph and the intersection is 33 ft wide. Our "design vehicle" is 20 ft long and can brake at 11.2 ft/sec2. If PIEV time is 1.4 seconds, what is the value of minimum safe clearance time (in seconds)?
On an accident inspection, average skid marks were found to be 65’. The damage inspection hinted at a speed range of 25-35mph at impact. If f=0.7, level roadway, and posted speed was 45mph, what is, in your opinion, the possible cause of the accident?
The length of a highway is 550 m when a head-on vehicle collision occurred. Police reports show that neither human error nor vehicle malfunction was the cause of the collision. Check if the length of the highway is sufficient for an overtaking maneuver. *Accident Report: Speed of Overtaking Car = 96 kph, Speed of Overtaken Car = 88 kph, Perception-reaction Time = 2.5 sec, Average acceleration = 2.4 m/sec2, Time of the passing vehicle occupying the left lane = 10.4 sec, Distance between the passing vehicle at the end of its maneuver and the opposing vehicle = 84m.
A two-lane highway (two 12-ft lanes) has a posted speed limit of 45 mi/h and one section has both horizontal and vertical curves, as shown in the figure below. A recent daytime crash (driver traveling eastbound and striking a stationary roadway object) resulted in a fatality and a lawsuit alleging that the 45 mi/h posted speed limit is an unsafe speed for the curves in question and was a major cause of the crash. Evaluate and comment on the roadway design if superelevation and radius, as well as SSD and K (rate of curvature) values of the road was adequate in safety provisions. Use g = 32.2 ft/sec2. Use 1.47 as conversion factor from mi/h to ft/s. Formula of rate of curvature is K = L/A hint: compare values of fs, SSD, and K with allowable values listed below allowable fs for 45 mi/h at e = 7.0%: 0.15 allowable SSD for 45 mi/h = 360 ft allowable K at 45 mi/h = 79