Traffic Flow and Analysis of Roads
Traffic Flow
- study of the movement of individual
drivers and vehicles between two
points and their interactions with one
another.
To represent traffic flow, relationships have
been established among three main
characteristics:
Flow, Density, and Velocity
- Assist traffic engineers in planning,
designing, and evaluating the
effectiveness of traffic engineering
measures on highway systems.
Time-Space Diagram
- Useful device for defining the
elements of traffic flow.
- Graph that describes the relationship
between the location of vehicles in a
traffic steam and the time as the
vehicles progress along the highway.
Flow (q)
- Equivalent hourly rate at which
vehicles pass a point on a highway
during a time period less than 1
hour.
Density (k)
- Concentration
- Number of vehicles traveling over a
unit length of highway at an instant
in time.
Speed (u)
- Distance travelled by a vehicle
during a unit of time.
Time Mean Speed
- Spot speed
- Arithmetic means the speeds of
vehicles passing a point within a
given interval of time.
Space Mean Speed
- Harmonic mean of the speeds of
vehicles passing a point on a
highway during an interval of time.
Headway
- Measurement of distance or time
between vehicles in the transit
system.
Time Headway
- Difference between the time when
the front of a vehicle arrives at a
point on the highway and the time
the front of the next vehicle arrives
at the same point.
Space Headway
- Difference in position between the
front of a vehicle and the front of the
next vehicle (in meters).
Fundamental Diagram of Traffic Flow
- Graphical representation that
illustrates the relationship between
traffic density, flow, and speed on a
roadway.
- Helps in understanding how these
variables interact and influence each
other, providing crucial insights for
traffic engineers to optimize road
capacity and improve traffic
management.
- Diagram’s three main zones: Free
Flow; Congested Flow; and
Breakdown, each indicating different
states of traffic conditions.
