Solution Manual Traffic Engineering 5th Edition Roess & Prassas & McShane |isbn 978-0134599717.

All Chapters Covered
W W




SOLUTIONS

, th
Traffic Engineering, 5 Edition W W




Roess, R.P., Prassas, E.S., and McShane, W.R.
W W W W W W




Solutions to Homework No. 2
W W W W




Problem 5‐1 W




A volume of 1,200 veh/h is observed at an intersection approach. Find the peak flow rate
W W W W W W W W W W W W W W W W




within the hour for the following peak-
W W W W W W




hour factors: 1.00, 0.90., 0.80, 0.70. Plot and comment on the results.
W W W W W W W W W W W




The peak flow rate of flow is computed as v = V/PHF. The table below summarizes the resul
W W W W W W W W W W W W W W W W W




ts for the information given. A plot follows.
W W W W W W W




Even with the same hourly volume,
W W W W W W




a small difference in PHF leads to a
W W W W W W W




n enormous difference in peak flo
W W W W W




w rates. Traffic engineers must be
W W W W W W




able to deal with this peaking char
W W W W W W




acteristic on a regular basis. W W W W




@@
SeSiesim
smiciicsiosloaltaiotinon

,Problem 5‐2 W




A traffic stream displays average vehicle headways of 2.4s at 55 mph. Compute the de
W W W W W W W W W W W W W W




nsity and rate of flow for this traffic stream.
W W W W W W W W




A headway can be converted to a flow rate as follows:
W W W W W W W W W W




v = 3600 = 3600 = 1,500 veh/hr/ln
W W W W W W W




h 2.4

Knowing both flow rate and speed (given), the density may now be computed as:
W W W W W W W W W W W W W




D = v = 1500 = 27.3 veh/hr/ln
W W W W W W W




S 55



Problem 5‐3 W




A freeway detector records occupancy of 0.26 for a 15- minute period. If the detector is
W W W W W W W W W W W W W W W




3.5 ft long, and the average vehicle has a length of 18 ft. what is the density implied by this
W W W W W W W W W W W W W W W W W W W W




measurement?

Density is obtained from occupancy as follows:
W W W W W W




Such a high value is indicative of highly congested conditions within a queue.
W W W W W W W W W W W W

, Problem 5‐4 W




The following traffic count data were taken from a permanent detector location on a maj
W W W W W W W W W W W W W W




or state highway. From this data, determine (a) the AADT, (b) the ADT for each month. (c)
W W W W W W W W W W W W W W W W W




the AAWT, and (d) the AWT for each month. From this information, what can be discerned
W W W W W W W W W W W W W W W W




about the character of the facility and the demand it serves?
W W W W W W W W W W




The table below illustrates the computation of monthly ADT and AWT values.
W W W W W W W W W W W




The AADT is computed as the total annual volume divided by 365 days, or:
W W W W W W W W W W W W W




AADT = 2,365,000 = 6,479 veh/day
W W W W W




365

The AAWT is computed as the total weekday volume divided by 260 days, or:
W W W W W W W W W W W W W




AAWT = 2,067,000 = 7,950 veh/day
W W W W W




260




@@
Se
Sie
sm icic
ism sioslo
altaiotinon