Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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Question
Chapter 10, Problem 8P
To determine
The saturation flow rate for a left turn lane that operates in a permitted only mode under the given condition.
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Students have asked these similar questions
3.
Determine the LOS for pedestrians at two-phase signalised intersection with a cycle
length of 90 s. the phase serving the major street vehicular traffic gets 50s of green
whereas the phase serving the minor street vehicular traffic gets 30 s of green.
Useful formula:
dp
Table for assessing the LOS
LOS
A
B
C
D
E
F
0.5(C-g)²
C
Average delay/pedestrian (s)
>5
≥ 5-10
> 10-20
>20-30
≥ 30-45
> 45
Determine the saturation flow rate (in veh/h) for a left-turn lane that operates in a permitted-only mode, under the following
conditions.
Opposing demand flow rate = 1,100 veh/h
Lane width 11.5 ft
Heavy vehicles = 4% of the traffic stream
Approach grade -6%
No on-street parking
No bus stops
Bicycle and pedestrian traffic conflicting with this lane group is negligible:
Intersection is not in a central business district
veh/h
A six-lane freeway (three lanes in each direction) in mountainous terrain has 10-ft lanes and obstructions 1 ft from the right edge. There are five ramps within three miles upstream of the segment midpoint and four ramps within three miles downstream of the segment midpoint. The traffic stream consists of mostly commuters with a peak hour factor of 0.84, peak-hour volume of 2500 vehicles, and 4% recreational vehicles. What is the level of service? (Write the letter only)
Chapter 10 Solutions
Traffic and Highway Engineering
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- Problem 2. Consider a freeway section with three lanes in each direction and with a length of 1.25mi (2km) and a +5% grade. In this freeway, the directional peak-hour volume is 3,800 veh/h, from which 76 are trucks and 152 are transit buses. The maximum 15-min volume within the hour of analysis is 1,055 vehicles. The lane widths are 12 ft (3.6m), and shoulder widths are 10 ft (3.1m). There are 2 exit ramps and 1 entrance ramp in the 3 miles in the upstream section and 1 exit ramp and 2 entrance ramp in the 3 miles in the downstream section (consider the same ramp density if using international (km) units). All transit buses will be removed from traffic since the transit service will be replaced by a commuter rail service. However, by removing buses, new additional passage car demand is expected. It is estimated that for each removed bus, 7 new passenger cars will be added to the original traffic volume of 3,800 veh/h. Question: Determine the change in speed and traffic density before…arrow_forwardDraw the intersection diagram for a given traffic volume summary of a T intersection and design the most appropriate and logical phasing pattern for the unsignalized intersection.arrow_forwardA new section of a freeway is to be designed with a free-flow-speed of 65 mph along of 0.75 mile on 5% upgrade. The expected traffic volume is 4200 v/hr. The traffic composition is 15% trucks, 5% recreational vehicles, and 10% buses. The peak hourly factor is 0.9, the unfamiliar driver factor is 0.95. If the design requirement is to target a level of service (B), how many lanes must be provided to satisfy the design requirement?arrow_forward
- Four-phases signal with a cycle time of 80 sec, Inter Green = 4 sec/phase, lost time / phase = 2 sec. Saturation flow on all approaches are similar, but the maximum traffic flows on two of the phases are triple the maximum traffic flows on the remaining two approaches, what will be actual green time on each phase ?arrow_forwardExample 5 A signalized intersection approach with no exclusive left- or right-turning lanes has a 35-second effective green out of a 60-second cycle. This approach has 4% of trucks and the approaching grade is 3%. Assume that the ideal saturation flow is 1,900 passenger vehs/h per lane. Determine the capacity of the intersection approach.arrow_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
- A four-lane freeway with the following characteristics: ten foot travel lanes lateral obstructions at 0 feet at the roadside total ramp density is 4.5 ramps/mile rolling terrain The roadway has a current peak demand volume of 3500 veh/h. The peak hour factor is 0.95 and there are no trucks, buses, or RVs in the traffic stream because the roadway is classified as a parkway and such vehicles are prohibited. At what level of service will the freeway operate during its peak period of demand?arrow_forwardAnalyze the unsignalized intersection below and calculate the optimum cycle length if the intersection will be signalized. Approach E W N S Maximum no. of lanes 5 5 4 4 Direction Through left Through left Through left Through left N Total volume pcu/hr 1,480 370 860 586 1,360 494 2,030 265 Sat. flow rate pcu/hr/lane 2,400 1,700 2,400 1,700 2,200 1,800 2,200 1,800arrow_forwardC] An urban freeway in an area with rolling terrain has 8 lanes (4 in one direction). It has 12-ft lanes and 4 ft shoulder clearance. The peak hour volume in peak direction is 6000 vph, with 8% trucks, and a peak hour factor of 0.90. On average there is one diamond interchange every 2 miles. Determine the following for the peak direction under study: (a). Passenger-car equivalent flow rate (pcphpl); (b). Estimated free-flow speed for prevailing conditions; (c). Average passenger car speed; (d). LOS.arrow_forward
- During the peak hour, an urban freeway segment has a traffic flow of 6,000 veh/h, with 4,000 vehicles with one occupant and 2,000 vehicles with two occupants. The freeway has five lanes, four of which are unrestricted opening to all vehicles regardless of vehicle occupancy and one lane that is restricted for use by vehicles with two occupants. Link performance functions for the length of this freeway segment are tu = 30+ 0.5vu for the unrestricted lanes and tr = 20+2vr for the restricted lane, where t’s are in minutes and v’s are in 1,000 vehicles. Solve for the distribution of traffic among the lanes using the SO principle and compare the savings in person hours relative to a UE solution, assuming that the compliance is perfect and that no single-occupant vehicles use the restricted lanes.arrow_forwardA six-lane freeway (three lanes in each direction) in mountainous terrain has 10-ft lanes and obstructions 5 ft from the right edge. There are zero ramps within three miles upstream of the segment midpoint and one ramp within three miles downstream of the segment midpoint. The traffic stream consists of mostly commuters with a peak hour factor of 0.84, peak-hour volume of 2500 vehicles, and 4% recreational vehicles. What is the level of service?arrow_forwardAn existing urban freeway with 4 lanes in each direction has the following characteristics. Traffic data: Peak hour volume (in the peak direction): Trucks: PHF = 0.93 Geometric data: LOS A LOS B LOS C LOS D LOS E LOS F Lane width: Shoulder width: Total ramp density: Terrain: rolling 11 ft 6 ft 1.8 ramps per mile Determine the LOS in the peak hour. (Assume commuter traffic and assume no RVs.) mean speed density 7,010 veh/h 10% of peak hour volume Show the demand flow rate (in pc/h/In), mean speed (in mi/h), and density (in pc/mi/In) for the given conditions. demand flow rate 2199 pc/h/In 54 X mi/h 41 X pc/mi/Inarrow_forward
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