All Chapters Covered
SOLUTIONS
@LECTJULIESOLUTIONSSTUVIA
, th
Traffic Engineering, 5 Edition
Roess, R.P., Prassas, E.S., and McShane, W.R.
Solutions to Homework No. 2
Problem 5‐1
A volume of 1,200 veh/h is observed at an intersection approach. Find the peak flow rate
within the hour for the following peak-hour factors: 1.00, 0.90., 0.80, 0.70. Plot and
comment on the results.
The peak flow rate of flow is computed as v = V/PHF. The table below
summarizes the results for the information given. A plot follows.
Even with the same hourly
volume, a small difference in
PHF leads to an enormous
difference in peak flow rates.
Traffic engineers must be able
to deal with this peaking
characteristic on a regular basis.
,@LECTJULIESOLUTIONSSTUVIA
, A traffic stream displays average vehicle headways of 2.4s at 55 mph. Compute the
density and rate of flow for this traffic stream.
A headway can be converted to a flow rate as follows:
v = 3600 = 3600 = 1,500 veh/hr/ln
h 2.4
Knowing both flow rate and speed (given), the density may now be computed as:
D = v = 1500 = 27.3 veh/hr/ln
S 55
Problem 5‐3
A freeway detector records occupancy of 0.26 for a 15- minute period. If the detector is
3.5 ft long, and the average vehicle has a length of 18 ft. what is the density implied by this
measurement?
Density is obtained from occupancy as follows:
Such a high value is indicative of highly congested conditions within a queue.
SOLUTIONS
@LECTJULIESOLUTIONSSTUVIA
, th
Traffic Engineering, 5 Edition
Roess, R.P., Prassas, E.S., and McShane, W.R.
Solutions to Homework No. 2
Problem 5‐1
A volume of 1,200 veh/h is observed at an intersection approach. Find the peak flow rate
within the hour for the following peak-hour factors: 1.00, 0.90., 0.80, 0.70. Plot and
comment on the results.
The peak flow rate of flow is computed as v = V/PHF. The table below
summarizes the results for the information given. A plot follows.
Even with the same hourly
volume, a small difference in
PHF leads to an enormous
difference in peak flow rates.
Traffic engineers must be able
to deal with this peaking
characteristic on a regular basis.
,@LECTJULIESOLUTIONSSTUVIA
, A traffic stream displays average vehicle headways of 2.4s at 55 mph. Compute the
density and rate of flow for this traffic stream.
A headway can be converted to a flow rate as follows:
v = 3600 = 3600 = 1,500 veh/hr/ln
h 2.4
Knowing both flow rate and speed (given), the density may now be computed as:
D = v = 1500 = 27.3 veh/hr/ln
S 55
Problem 5‐3
A freeway detector records occupancy of 0.26 for a 15- minute period. If the detector is
3.5 ft long, and the average vehicle has a length of 18 ft. what is the density implied by this
measurement?
Density is obtained from occupancy as follows:
Such a high value is indicative of highly congested conditions within a queue.
