Solution Manual for Traffic Engineering (5th Edition by Roess, Prassas & McShane) – Complete Problem Solutions

AllChaptersCovered
c c




SOLUTIONS

, th
Traffic Engineering, 5 Edition c c




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




SolutionstoHomeworkNo. 2 c c c c




Problem 5‐1 c




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




within the hour for the following peak-hour factors: 1.00, 0.90., 0.80, 0.70. Plot and comment
c c c c c c c c c c c c c c c




on the results.
c c c




Thepeakflow rateofflow iscomputed asv =V/PHF. Thetablebelowsummarizesthe results for
c c c c c c c c c c c c c c c c c c




the information given. A plot follows.
c c c c c c




Evenwiththesamehourlyvolume, a
c c c c c c




small difference in PHF leads to an
c c c c c c c




enormous difference in peak flow
c c c c c




rates. Traffic engineers must be
c c c c c




able to deal with this peaking
c c c c c c




characteristic on a regular basis.
c c c c c




@@
SeSiesim
smiciicsiosloaltaiotinon

,Problem 5‐2 c




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




density and rate of flow for this traffic stream.
c c c c c c c c c




A headwaycan beconverted toa flowrateasfollows:
c c c c c c c c c c




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




h 2.4

Knowingbothflowrateand speed(given),thedensitymaynowbecomputed as:
c c c c c c c c c c c c c




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




S 55



Problem 5‐3 c




Afreewaydetectorrecordsoccupancyof0.26fora15-minuteperiod. Ifthedetectoris
c c c c c c c c c c c c c c c




3.5 ftlong,andthe average vehicle hasalengthof18 ft.whatisthe densityimpliedby this
c c c c c c c c c c c c c c c c c c c




measurement?
c




Densityisobtainedfromoccupancyasfollows:
c c c c c c




Suchahigh valueisindicativeofhighlycongested conditionswithinaqueue.
c c c c c c c c c c c c

, Problem 5‐4 c




The following traffic count data were taken from a permanent detector location on a major
c c c c c c c c c c c c c c




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




AAWT,and(d)theAWTforeachmonth. From thisinformation,whatcan be discerned about
c c c c c c c c c c c c c c c c




the character of the facility and the demand it serves?
c c c c c c c c c c




ThetablebelowillustratesthecomputationofmonthlyADTandAWTvalues.
c c c c c c c c c c c




The AADT is computedasthe total annual volumedivided by365 days,or:
c c c c c c c c c c c c c




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




365

The AAWT iscomputedasthe totalweekday volumedivided by260 days,or:
c c c c c c c c c c c c c




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




260




@@
Se
Sie
sm icic
ism sioslo
altaiotinon