The average speed of vehicles on a road with a downgrade of 4% is 90 kph. A traffic study was conducted to improve the braking distance (reduce the braking distance) due to a high risk of accident occurrence on this road during the night. a. If the existing braking distance is 120 m, determine what would be the recommended speed limit based on a reduction in braking distance of 20%. Use Table 1 for values of coefficient of friction f according to design speeds. You may interpolate in between values. Answer: v = 80.10 kph b. If the grade is to be reduced to achieve this reduction in braking distance, what would the new grade of the road be? Answer: G = +3.48% Table 1. Running Speed vs. Coefficient of Friction Running Speed, kph Coeff of Friction f 102 85 68 54 45 36 30 20 0.29 0.30 0.31 0.33 0.35 0.38 0.44 0.44 Source: AASHTO 1984

The average speed of vehicles on a road with a downgrade of 4% is 90 kph. A traffic study was conducted to improve the braking distance (reduce the braking distance) due to a high risk of accident occurrence on this road during the night. a. If the existing braking distance is 120 m, determine what would be the recommended speed limit based on a reduction in braking distance of 20%. Use Table 1 for values of coefficient of friction f according to design speeds. You may interpolate in between values. Answer: v = 80.10 kph b. If the grade is to be reduced to achieve this reduction in braking distance, what would the new grade of the road be? Answer: G = +3.48% Table 1. Running Speed vs. Coefficient of Friction Running Speed, kph Coeff of Friction f 102 85 68 54 45 36 30 20 0.29 0.30 0.31 0.33 0.35 0.38 0.44 0.44 Source: AASHTO 1984

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 10P

See similar textbooks

Similar questions

The average speed of vehicles on a road with a downgrade of 4% is 90 kph. A traffic study was conducted to improve the braking distance (reduce the braking distance) due to a high risk of accident occurrence on this road during the night. a. If the existing braking distance is 120 m, determine what would be the recommended speed limit based on a reduction in braking distance of 20%. Use Table 1 for values of coefficient of friction f according to design speeds. You may interpolate in between values. Answer: v= 80.10 kph b. If the grade is to be reduced to achieve this reduction in braking distance, what would the new grade of the road be? Answer: G=+3.48% Table 1. Running Speed vs. Coefficient of Friction Running Speed, kph Coeff of Friction f 102 85 68 54 45 36 30 20 0.29 0.30 0.31 0.33 0.35 0.38 0.44 0.44 Source: AASHTO 1984
Q2: One lane of 2- lane carriage of highway is closed for repairs, the free flow speed in the 2- lane portion of highway is 60 km/ hr, the observation showed that the free flow speed in the bottleneck section is also 60 km/ hr. The space headway of vehicles in stationary condition is 12.5 m. If the traffic volume is 1600 veh/ hr. Find the following (assume linear relationship between speed and density). 1. The mean speed of the traffic immediatley before the bottleneck section. 2. The queue length of vehicles after 30 minutes from the beginning of repair operation.
1.) A truck going uphill on a one lane road with 10% grade has left brake marks of 10.49 m on the pavement to avoid colliding with a car traveling down the road at 100 km/h. Assuming that the vehicles applied breaks at the same time. What minimum distance should be visible to drivers of the vehicles to avoid collision? (take µ= 0.70 and break efficiency n=0.70 for both vehicles, mass factor = 1.04, tr=2.5 seconds) a.) use practical breaking distance b.) use theoretical brake distance
The gap between 2 consecutive automobiles is 25 meters. At a certain time the front vehicle is traveling at 85 kph and the following vehicle at 60 kph. If both vehicles start accelerating at the same time, determine the gap between two vehicles after 21 seconds if the acceleration of the vehicles can be assumed to take the following forms: du / dt = 1.04 – 0.080ut (leading vehicle) du / dt = 1.03 - 0.075ut ( following vehicle)
An engineering student examining the scene of an accident, observe skid marks 30.0m long by a 1600kg car. The car skidded to a stop on a concrete highway having a coefficient of kentic with the tires of 0.75. Estimate the car speed of the beginning of the speed.
Problem 08 If the velocity of moving vehicles on a road is 24 kmph, stopping distance is 19 m and the average length of vehicles is 6 m, the basic capacity of the lane is a. 760 vehicles/hour b. 860 vehicles/hour c. 960 vehicles/hour d. 1060 vehicles/hour
A vehicle (SUV) is to overtake a bus as it enters an acceleration lane. The speed of the SUV is 80 kph initially. The bus is at the same speed as the SUV. Given the perception reaction time as 2.70 seconds and the average acceleration of the vehicle is 2.55 m/s2, solve the following: provide solution asap a. The distance (in ft) traversed during the perception and reaction time and during the initial acceleration to the point of encroachment on the left lane.b. The distance (in yard) travelled by the passing vehicle occupies the left lane if the opposing vehicle travelled at 75 kph and the time for the passing vehicle to occupy the left lane is 20 seconds. c. The minimum passing sight distance (in m) if the SUV's velocity to overtake the bus is 55.92 miles per hour while the distance between the opposing vehicle and the SUV after its !PAnguygt is 295 ft. The time for the SUV to occupy the left lane is 0.23 minutes. d. The passing sight distance (in furlong) that the SUV could move…
During a braking test, a car is brought to rest beginning from an initial speed of 54 mi/hr in a distance of 143 ft. With the same constant deceleration, what would be the stopping distance s from an initial speed of 83 mi/hr? Answer:s = i ft
Current Attempt in Progress A car is traveling around a circular track of 670-ft radius. If the magnitude of its total acceleration is 6.1 ft/sec² at the instant when its speed is 33 mi/hr, determine the rate at at which the car is changing its speed. Answer: at = ±i eTextbook and Media ft/sec²
On a two-lane road, the lane width is 3.2 m, and the shoulder widths on both sides of the road are 1 m. In a horizontal curve with a radius of 500 m, a direct speed will be formed according to the project speed Vp = 90 km / h; According to this information, answer the following questions. a- Calculate the maximum value (dmax) in the frog (%). b- Determine the Ld speed application length (m) Note : please answer both a and b... Please give me both answer... Thank you
The average speed of vehicles on an expressway is being studied. a. Suppose observation on 50 vehicles yielded a sample mean of 65 km/hr. Assume that the standard deviation of vehicle speed is known to be 6 km/hr. Determine the two-sided 99% confidence intervals of the mean speed. b. In part (a), how many additional vehicles' speed should be observed such that the mean speed can be estimated to within + 1 km/hr with 99% confidence? C. Suppose John and Mary are assigned to collect data on the speed of vehicles on this expressway. After each person has separately observed 10 vehicles, what is the probability that John's sample mean will exceed Mary's sample mean by 2 km/hr? d. Repeat part (c) if each person has separately observed 100 vehicles instead?
Vehicles are driving at 35 miles/hour in a roadway. A slow truck joins the traffic at 15 mile/hour for 1.5 miles. Assume the following q-k model and traffic parameters. Uf=60; Kj=120;qcap=1800; q=60k-0.5k^2. Using shockwave analysis, determine the following: Q1: When the truck pulls off the road, how long is the queue behind the truck? Q2: After the truck pulls off the road, how long it takes for the queue to disappear?