Complete Solution Manual for Traffic Engineering, 5th Edition by Roess, Prassas & McShane | All Chapters Covered | Verified Solutions

All Chapters Covered
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SOLUTIONS

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Traffic Engineering, 5 Edition j j


Roess, R.P., Prassas, E.S., and McShane, W.R.
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Solutionsto HomeworkNo. 2 j j j j




Problem 5‐1 j




A volume of 1,200 veh/h is observed at an intersection approach. Find the peak flow rate withi
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n the hour for the following peak-
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hour factors: 1.00, 0.90., 0.80, 0.70. Plot and comment on the results.
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The peakflow rate of flow iscomputed asv = V/PHF. The table below summarizes the results fo
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r the information given. A plot follows.
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Evenwiththesamehourly volume, a
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small difference in PHF leads to an e
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normous difference in peak flow rat
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es. Traffic engineers must be able to
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deal with this peaking characteristic
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on a regular basis.
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,Problem 5‐2 j




A traffic stream displays average vehicle headways of 2.4s at 55 mph. Compute the densit
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y and rate of flow for this traffic stream.
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A headway can be converted to a flow rate as follows:
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v = 3600 = 3600 = 1,500 veh/hr/ln
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h 2.4

Knowingboth flow rateand speed (given), thedensity may now be computed as:
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D = v = 1500 = 27.3 veh/hr/ln
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S 55



Problem 5‐3 j




A freeway detector records occupancy of 0.26 for a 15- minute period. If the detector is
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3.5 ft long, and the average vehicle has a length of 18 ft. what isthe density implied by this meas
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urement?

Density is obtained fromoccupancy as follows:
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Such a high valueis indicative ofhighly congested conditions within a queue.
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, Problem 5‐4 j




The following traffic count data were taken from a permanent detector location on a major st
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ate highway. From this data, determine (a) the AADT, (b) the ADT for each month. (c) the AAW
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T, and (d) the AWTfor each month. From this information, what can be discerned about the ch
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aracter of the facility and the demand it serves?
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Thetablebelow illustratesthe computation ofmonthly ADT and AWT values.
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The AADT is computed as the total annual volume divided by 365 days, or:
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AADT = 2,365,000 = 6,479 veh/day
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365

The AAWT is computed as the total weekday volume divided by 260 days, or:
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AAWT = 2,067,000 = 7,950 veh/day
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260




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