Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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Question
Chapter 9, Problem 7P
To determine
The number of lanes required to provide LOS C.
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An urban freeway is to be designed using the following information.
AADT = 52,500 veh/day K (proportion of AADT occurring during the peak hour): 0.12
D (proportion of peak hour traffic traveling in the peak direction): 0.65
Trucks: 8% of peak hour volume
PHF = 0.94
Lane width: 12 ft
Shoulder width: 10 ft
Total ramp density: 0.5 interchange/mile; all interchanges are to be cloverleaf interchanges
Terrain: rolling
Determine the number of lanes in the peak direction required to provide LOS C. (Assume commuter traffic and assume no RVs.)_______ lanes
Show all calculations required. (Calculate your answers for the peak direction only. Enter fHV, the peak hour volume in veh/h, the free flow speed in mi/h, the demand flow rate in pc/h/ln, the mean speed in mi/h, and the density in pc/mi/ln.)
fHV ________
peak hour volume___________veh/h
free flow speed_______ mi/h
demand flow rate___________ pc/h/ln
mean speed_________ mi/h
density_____________ pc/mi/ln.
An urban freeway is to be designed using the following information.
AADT = 52,500 veh/day
K (proportion of AADT occurring during the peak hour):
D (proportion of peak hour traffic traveling in the peak direction):
Trucks:
PHF = 0.94
Lane width:
Shoulder width:
Total ramp density:
Terrain:
3
Determine the number of lanes in the peak direction required to provide LOS C. (Assume commuter traffic and assume no RVs.)
lanes.
0.12
0.65
8% of peak hour volume
demand flow rate
12 ft
10 ft
0.5 interchange/mile; all interchanges are to be cloverleaf interchanges
rolling
HV'
Show all calculations required. (Calculate your answers for the peak direction only. Enter fy, the peak hour volume in veh/h, the free flow speed in mi/h, the demand flow rate in pc/h/In, the mean speed in mi/h, and the density in pc/mi/ln.)
fHV
peak hour volume
0.893
free flow speed
mean speed
density
6300
X
Your response differs from the correct answer by more than 10%. Double check your calculations. veh/h
1500
X
Your…
A four-lane basic freeway segment on level terrain is being redesigned. The current roadway
has 12 ft lanes with 4 ft shoulders. The proposed alignment would expand to six 11-ft lanes
with 2 ft shoulders. The road carries 3000 vehicles in the peak hour in one direction, with 925
coming in the peak 15 minutes. The truck mix is 70/30 and makes up 10% of traffic. What is
the density and LOS (level of service) before and after the proposed change?
Chapter 9 Solutions
Traffic and Highway Engineering
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- A 5% upgrade on a six-lane freeway (three lanes in each direction) is 1.25 mi long. On this segment of freeway, the directional peak-hour volume is 3800 vehicles with 2% large trucks and 4% buses (no recreational vehicles), the peak- hour factor is 0.90, and all drivers are regular users. The lanes are 12 ft wide, there are no lateral obstructions within 10 ft of the roadway, and the total ramp density is 1.0 ramps per mile. A bus strike will eliminate all bus traffic, but it is estimated that for each bus removed from the roadway, seven additional passenger cars will be added as travelers seek other means of travel. a.) What is density, before the bus strike? b.) What is the volume-to-capacity ratio, before the bus strike? c.) What is the level of service of the upgrade segment before the bus strike? d.) What is density, after the bus strike? e.) What is the volume-to-capacity ratio, after the bus strike? f.) What is the level of service of the upgrade segment after the bus strike?arrow_forwardAn existing urban freeway with 4 lanes in each direction has the following characteristics. Traffic data: Peak hour volume (in the peak direction): 7,110 veh/h Trucks: 10% of peak hour volume PHF = 0.93 Geometric data: Lane width: 11 ft Shoulder width: 6 ft Total ramp density: 1.8 ramps per mile Terrain: rolling Determine the LOS in the peak hour. (Assume commuter traffic and assume no RVs.) LOS A LOS B LOS C LOS D LOS E LOS F Show the demand flow rate (in pc/h/ln), mean speed (in mi/h), and density (in pc/mi/ln) for the given conditions. demand flow rate pc/h/lnmean speed mi/h density pc/mi/lnarrow_forwardA two-lane rural highway carries a peak hour volume of 465 (vph) and has the following characteristics: Roadway: 60mph design; 11 foot lanes, 2 foot shoulders; rolling terrain; 60% no-passing zones; length = 3 miles. Traffic: 70/30 directional split; 4% trucks; 2 percent recreational vehicles; 1 percent buses; PHF = 0.95 a) What Level of Service will the highway operate under during peak periods? b) What is the capacity of the highway? Explain why this is less than 2,800 (vph)?arrow_forward
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