QUESTION 2 Under what traffic conditions will you be able to use the Greenshields model but not the Greenberg model? Give reason for your answer. The table below shows data on speeds and corresponding densities on a section of a rural collector road. If it can be assumed that the traffic flow characteristics can be described by the Greenberg model, develop an appropriate relationship between the flow and density. Also determine the capacity of this section of the road. Speed (mi/h) Density (veh/mi) 60.0 46.0 40.8 39.3 35.7 32.6 30.8 28.4 24.7 18.5 20 32 38 40 45 50 53 57 65 80

QUESTION 2 Under what traffic conditions will you be able to use the Greenshields model but not the Greenberg model? Give reason for your answer. The table below shows data on speeds and corresponding densities on a section of a rural collector road. If it can be assumed that the traffic flow characteristics can be described by the Greenberg model, develop an appropriate relationship between the flow and density. Also determine the capacity of this section of the road. Speed (mi/h) Density (veh/mi) 60.0 46.0 40.8 39.3 35.7 32.6 30.8 28.4 24.7 18.5 20 32 38 40 45 50 53 57 65 80

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 21P

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Question 2 Because the new travel time rate (TTR) from the additional traffic (e.g., 300vph) exceeds the minimum acceptable local standard of 2.0 min/mile, it is proposed to increase the road capacity by 900vph/lane by adding one lane in each direction. Calculate the new travel time rate and traffic volume using: a. The traditional method of traffic impact analysis, and b. The above-mentioned pivot point analysis method. c. Compare the results of the two methods and comment on their significance.
1. A study of freeway flow at a given site has yielded a relationship speed-density calibrated as follows: S = 57,5(1 - 0,008 D) For this relationship, specify: (a) free flow velocity, (b) congestion density, (c) velocity-flow relationship (d) flow density relationship, and (e) capacity. 2. Answer all the questions in Problem 1 for the calibrated density-velocity relationship the following: S = 61.2e^-0015D
The traffic demand for a six-lane urban arterial road (three lanes per direction) is given in the table below. The relationship between flow and density for this road follows GreenShiled's model, with a free flow speed of 105 km/h and a jam density of 92 veh/km/lane. Two of the three lanes of the EB direction were closed at 5:00 AM for maintenance. The two lanes were re-opened at 8:00 AM, allowing the traffic to be released at capacity conditions. a) What is the maximum length of the queue upstream of the bottleneck? b) At what time the queue upstream of the bottleneck will be fully dissipated? c) What is the furthest point upstream of the bottleneck that will be impacted by the lane closure? d) Draw the shock wave diagram showing shock wave speeds, critical times, and distances. Time 5:00 6:00 AM 6:00 7:00 AM 7:00 8:00 AM 8:00 9:00 AM 9:00 10:00 AM 10:00 11:00 AM Demand (vph) 2000 4000 6400 6000 3600 3000
AADT of 1650 veh/hr. 12 crashes over 2 year period four of which were injury crashes. if the RMVM = 2.236, then what is the length in miles of this highway?
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Use linear regression to fit the highway speed/density data shown here to the Greenshields model, and use it to determine: a. The mean free flow speed b. The jam density The capacity The speed at max flow R² of this data
H.w Try only ten): 1. The flow is zero on the highway only if the density equals to zero. 2. Density is the number of vehicle passing during a given width of lane of roadway. 3. If an accident occure during the way, it could be say that it is uninterreputed flow. 4. Mobility for arterial road is grater than the mobility of local road. 5. 85 th percentile of spot speed cumulative curve represents the highway speed limit. 6. One of the most important of on street parking is mechanical garage. 7. As angle of parking increase, more accidents would be occure. 8. At jam density, density of flow is zero. 9. PHF of rural region is less than the PHF in urban region. 10.Stopping time delay occure ar intersection. 11.Future traffic includes only generated and developed traffic. 12.As the tunover duration of the parking increase, operation of the parking increases also.
An existing Class I two-lane highway is to be analyzed to determine the two-way level of service, given the following information: Traffic data: PHV _ 600 veh/h 60% in the peak direction 8% trucks 2% recreational vehicles PHF = 0.86 No-passing zones: 40% Geometric data: Rolling terrain BFFS _ 55 mi/h Lane width _ 11 ft Shoulder width _ 2 ft 8 access points per mile
The table below shows data on speeds and corresponding densities on a section of a rural collector road. If it can be assumed that the traffic flow characteristics can be described by the Greenberg model, develop an appropriate relationship between the flow and density. Also determine the capacity of this section of the road.
QUESTION 9 The adjustment for the access point density is based on empirical studies indicating that for each access point per mile, the estimated FFS decreases by 0.25 mi/h, regardless of the type of median. Note that these access points are those that influence traffic flow and that access points that go unnoticed by drivers are not included in the calculation of the access point density. Therefore, what is the expected reduction (mph) in FFS when the access density is 4 access points per mile. (enter a positive value)
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