discussions

Question 1

The number of vehicles (n) passing some
designated roadway point in a given time interval
(t)

Answer 1

Flow (q)

Question 2

• Units typically vehicles/hour
• Volume typically refers to flow in an hour

Answer 2

Flow (q)

Question 3

Flow is constantly _____

Answer 3

varying

Question 4

peak 15-minute flow
within the hour of interest.

Answer 4

Analysis flow rate

Question 5

How much space do you leave
between vehicles?

Answer 5

• 2 chevrons!
• Depends on speed
• Varies for each person

Question 6

The distance (ft) between successive
vehicles in a traffic stream, as measured
from front bumper to front bumper

Answer 6

Spacing

Question 7

the number of vehicles over a length of
freeway

Answer 7

Density

Question 8

– Measured by loop detectors
– The percent of time the loop is covered by a
vehicle

Answer 8

Occupancy

Question 9

The time (in seconds) between successive
vehicles, as their front bumpers pass a
given point.

Answer 9

Headway (h)

Question 10

The average speed of vehicles that pass
by a specific point in space over a specific
time period

Answer 10

TMS

Question 11

Time necessary for a vehicle to travel a
length of roadway

Answer 11

SMS

Question 12

– Taken at a specific point
– Average of instantaneous speeds

Answer 12

Time mean speed

Question 13

– Harmonic speed
– Look at a segment of roadway
– Average speed of all vehicles in that segment

Answer 13

Space mean speed (u)

Question 14

• Arithmetic mean of speeds observed at some
  point
• Easy to measure

Answer 14

Time Mean Speed

Question 15

• It is the harmonic mean
• Used in traffic models, but harder to measure

Answer 15

Space Mean Speed

Question 16

• The number of vehicles (n)
  occupying a given length (l)
  of a lane or roadway at a
  particular instant
• Unit of density is vehicles
  per mile (vpm).

Answer 16

Density (k - konzentration)

Question 17

• Number of vehicles in
  length of segment
• Inverse of average spacing

Answer 17

Density (k)

Question 18

• A model for the relationship
  between flow, density, and
  speed
• Represents idealized
  behavior and fundamental
  relationships
• Useful for traffic analysis

Answer 18

Traffic Flow Theory

Question 19

The speed at which vehicles will travel
unimpeded

Answer 19

Free-flow speed (uf)

Question 20

The density of vehicles in stopped traffic

Answer 20

Jam density (kj)

Question 21

The maximum flow a section of roadway can
maintain

Answer 21

Capacity (qm)

Question 22

______ can easily be measured by remote
sensing, but has historically been difficult to
measure
– Use occupancy obtained from loop-detectors

Answer 22

Density

Question 23

TMS more easy to measure than SMS
– Use correction or approximation
– Easy to measure with remote sensing (GPS)

Answer 23

true

Question 24

• Flow is easy to measure
• Occupancy is measure of density
• Only need to measure 2 of 3

Answer 24

true

Question 25

_____________ decreases when a car is on top of it.

Answer 25

Loop inductance

Question 26

Single loops can measure:

Answer 26

– Occupancy (O): % of time loop is occupied per interval – Volume (N): vehicles per interval

Question 27

How do you estimate speed from a single loop detector?

Answer 27

* You know how long it took the object to pass over the detector * You know the percent of time (in a short interval) the loop was covered by a vehicle

Question 28

PHF

Answer 28

peak hour factor

Question 29

used to account for the variation of traffic flow within the peak hour itself

Answer 29

peak hour factor (PHF)

Question 30

defined as the maximum hourly rate at which persons or vehicles can reasonably be expected to transverse a point or uniform section of a lane or roadway during a given time period under prevailing roadway, traffic, and control conditions.

Answer 30

Capacity

Question 31

a qualitative description of how a certain facility is performing.

Answer 31

level of service (LOS)

Question 32

PHPM

Answer 32

Philippine Highway Planning Manual

Question 33

uses qualitative measures that characterize operational conditions within a traffic stream and perception of these conditions by motorists and passengers.

Answer 33

LOS concept

Question 34

defined as the number of vehicles in a given length of road at an instant point in time.

Answer 34

Density

Question 35

the time interval between passage of consecutive vehicles at a specified point on the road with a unit of time per vehicles.

Answer 35

Time headway

Question 36

the distance between two vehicles measure from the front bumper of a vehicle to that of another.

Answer 36

Spacing

Question 37

It can only be measure, however, if a detector is installed at a specific point on the carriageway. It is defined as the total time of a detector is occupied divided by the total time of observation.

Answer 37

time occupancy

Question 38

the motion or propagation of a change in density and flow

Answer 38

Shock wave

Question 39

occur when there is a change in the travel condition on the roadway that affect the stream flow.

Answer 39

shock wave

Question 40

are associated with a particular vehicle in the stream slowing down or stopping

Answer 40

Shock waves

Question 41

might be associated with the pressure being released and a traffic jam dissipating

Answer 41

shock wave