Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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Chapter 13, Problem 4P
To determine
(a)
The net user benefits per year.
To determine
(b)
The comparison of calculated value with that of typical highway studies
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Q2: a. Show how to determine the number of lanes for a rural highway required to
serve a current volume 5000 veh/day. The following data are to be used: annual
growth rate = 4%, design and construction period = 22 years, percent of trucks =
10 (pc equivalent factor = 2), design capacity of lane = 900 pc/hr/lane and the
directional distribution factor = 75%.
Consideration is being given to increasing the toll on a bridge now carrying
4500 veh/day. The current toll is $1.35/veh. It has been found from past
experience that the daily traffic volume will decrease by 400 veh/day for
each 25¢ increase in toll. Therefore, if x iš the increase in toll in cents/veh,
the volume equation for veh/day is V= 4500 - 400 (x/25), and the new
toll/veh would be T = 135 + x. In order to maximize revenues, what would
the new toll charge be per vehicle, and what would the traffic in veh/day
be after the toll increase?
For this exercise, you are to design a roadway that is to carry 100,000 people a day (excluding
truck occupants) – 50,000 in design direction. The vehicles that carry these people include; (1)
personal vehicles (average occupancy of 1.2 people per car) 2-2 kip single axles, and (2) buses
with 2-22 kip single axles (assume they are filled with an average of 40 passengers). There are
also trucks on the roadway and all trucks have 1-40 kip triple axle, 1-32 kip tandem axle, and 1-8
kip single axle. You know that the soil CBR is 6, the initial PSI is 4.5 and the TSI is 2.5. Other
values to be used:
All drainage coefficients = 1.0
Reliability = 90%
Overall standard deviation of traffic = 0.50
Concrete Modulus of Elasticity = 5.5 million lb/in2
Concrete Modulus of Rupture = 750 lb/in2
PCC load transfer coefficient = 3.0
Design a rigid and flexible pavement, to last 15 years, for a four-lane road (four lanes in design
direction) with 400 trucks per day in the design direction, and…
Chapter 13 Solutions
Traffic and Highway Engineering
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- A bridge has been constructed between the mainland and an island. The total cost (excluding tolls) to travel across the bridge is expressed as C- 50 + 0.5V, where V is the number of veh/hr and Cis the cost/vehicle in cents. The demand for travel across the bridge is V- 2500 - 10C. (a) Determine the volume of traffic across the bridge. (b) If a toll of 25 cents is added, what is the volume across the bridge? What volume would be expected with a 50 cent increase? 155 (c) A tollbooth is to be added, thus reducing the travel time to cross the bridge. The new cost function is C- 50 + 0.2V. Determine the volume of traffic that would cross the bridge. (d) Determine the toll to yield the highest revenue for demand and supply function in part (a), and the associated demand and revenuearrow_forwardAverage demand on a rural roadway ranges from zero to 600 veh/day when the cost per trip goes from $1.75 to zero. (a) Calculate the net user benefits per year (in dollars) if the cost decreases from $1.50 to $0.75/trip (assume a linear demand function). $ 29 x Your response is within 10% of the correct value. This may be due to roundoff error, or you could have a mistake in your calculation. Carry out all intermediate results roundoff error. (b) Compare the value calculated in (a) with the benefits as calculated in typical highway studies. (Enter the benefits in dollars as calculated in typical highway studies.) $ 88000 x Your response is within 10% of the correct value. This may be due to roundoff error, or you could have a mistake in your calculation. Carry out all intermediate results E roundoff error.arrow_forwardTwo routes connect an origin-destination pair with performance functions t₁ = 5 + (x₁/2)² and t₂ = 7+ (x2/4)² (with t's in minutes and x's in thousands of vehicles per hour). It is known that at user equilibrium, 75% of the origin-destination demand takes route 1. What percentage would take route 1 if a system-optimal solution were achieved, and how much travel time would be saved?arrow_forward
- The demand and supply function for a bridge are the following where C is cost in cents and V is volume in veh / h . Demand V = 1500 - 10C Supply or cost function: C = 120 + 0.5V (a) What is the equilibrium volume of traffic and the associated cost? (b) 20 cents of toll is added to the cost function, what will be the new cost function and the equilibrium volume?arrow_forwardA toll bridge carries 10,000 veh/day. The current toll is $3.00/vehicle. Studies have shown that for each increase in toll of 50 cents, the traffic volume will decrease by 1000 veh/day. It is desired to increase the toll to a point where revenue will be maximized. Let V be the Volume X be the increase in toll charge (a) Write the expression for travel demand on the bridge related to toll increase and current volume. (b) Determine the increase in toll charge (c) Determine the new toll charge to maximize revenues. (d) Determine traffic in veh/day after toll increase. (e) Determine total revenue increase with new toll.arrow_forward3. Three routes connect an origin-destination pair with performance functions: ti=20 +0.51 t₂ = 4+2x2 tε = 3 +0.2x² with t in minutes and r in thousand vehicles per hour. (a) Determine the User Equilibrium flow on each route if q = 4000veh/h. (b) What is the minimum q (origin-destination demand) to ensure that all the three routes are used under user equilibrium? (c) Suppose that Route 1 is closed for repair. Find the system optimal flow on routes 2 and 3 and compute the total travel times.arrow_forward
- Two routes connect an origin and destination with performance function t; = aj + (xj/cj)2 (with t's in minutes and x's in thousands of vehicles per hour). It is known that at user equilibrium, 65% of the origin-destination demand takes route 1. How many vehicles (in thousands) will take route 1 if system optimal equilibrium is archived? Route 1 Route 2 a 7 2 3arrow_forwardTwo routes connect a city and suburb. During the peak-hour morning commute, a total of 5000 vehicles travel from the suburb to the city. Route 1 has a 50km/hr speed limit and 5km in length, Route 2 has a 55km/hr speed limit and 4 km in length. Studies show that the total travel time on route 1 increases 2 mins for every extra 500 vehicles added. Mins of travel time on route 2 increase with the square of the no. of vehicles expressed in 000’s. Determine user equilibrium travel times.arrow_forwardThe Department of Traffic is considering three improvement plans for a heavily traveled road within the city. The road improvement is expected to achieve three goals: improve travel speeds, increase safety, and reduce operating expenses for motorists. The annual dollar value of savings compared with existing conditions for each criterion and additional construction and maintenance costs is shown in Table 1. If the economic life of the road is considered to be 53 years and the discount rate is 4%, which alternative should be selected? Evaluate the two proposals based on economic evaluation criteria using the Net Present Worth (NPW) and benefit-cost ratio (BCR) methods for economic analysis.arrow_forward
- The daily counts of the current traffic volume for a rural highway for one week of May 2000 are as shown in the following table: Sat. Sun. Mon. Tues. Wed. Thur. Fri. Day Daily volume 12000 12500 10500 11500 9500 9000 8500 The traffic is composed of 70% passenger car, 20% bus, 10% truck. The percent of future traffic to current traffic is predicted to be 180% up to May 2020. Determine the required number of lanes for this highway if the lane capacity is 1300 pc/hr.arrow_forwardа. The Department of Traffic is considering three improvement plans for a heavily traveled road within the city. The road improvement is expected to achieve three goals: improve travel speeds, increase safety, and reduce operating expenses for motorists. The annual dollar value of savings compared with existing conditions for each criterion and additional construction and maintenance costs is shown in Table 1. If the economic life of the road is considered to be. Table 1: Cost and Benefits for Improvement Plans concerning Existing Conditions Alternative Construction Annual Annual Annual Annual Cost ($) Saving Cost Travel Time Operation Maintenance in Benefits($) Saving($) Cost($) Accidents($) 185.000 5000 3000 300 1500 220,000 5000 6500 500 2500 II 310,000 7000 6000 2800 3000arrow_forward8.18 Two routes connect an origin and a destination. Routes 1 and 2 have performance functions t₁ = 2 + x₁ and t₂ = 1 + x2, where the 's are in minutes and the x's are in thousands of vehicles per hour. The travel times on the routes are known to be in user equilibrium. If an observation for route 1 finds that the gaps between 30% of the vehicles are less than 6 seconds, estimate the volume and average travel times for the two routes. (Hint: Assume a Poisson distribution of vehicle arrivals, as discussed in Chapter 5.)arrow_forward
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