4B, 4C, AND 4D Flashcards
The decision to travel for a given purpose
TRIP GENERATION
These
generated trips from each zone are then distributed to all other zones based on
the choice of destination
TRIP DISTRIBUTION
There are several methods to distribute trips
among destinations; and two such methods are:
GROWTH FACTOR MODEL
GRAVITY MODEL
a method which responds only to relative growth
rates at origins and destinations, and this is suitable for short term trend
extrapolation.
GROWTH FACTOR MODEL
start from assumptions about trip making
behavior and the way it is influenced by external factors
An important aspect of
the use of __________ is their calibration, that is the task of fixing their
parameters so that the base year travel pattern is well represented by the model.
GRAVITY MODELS
The most widely used and documented trip distribution model, which states that the number of trips between two zones is directly proportional
to the number of trip attractions generated by the zone of destination and
inversely proportional to a function of time of travel between the two zones.
GRAVITY MODEL
are used primarily to
distribute trips between zones in the study area and zones in cities external to the
study area
GROWTH FACTOR MODELS
The most popular growth factor model.
FRATAR METHOD
process by which the trips between traffic analysis zones in study
area are allocated to available modes.
MODE CHOICE
aspect of the demand analysis process that determines
the number (or percentage) of trips between zones that are made by automobile
and by transit.
MODE CHOICE
4 TYPES OF MODE CHOICE MODELS
- DIRECT GENERATION MODELS
- TRIP END MODELS
- TRIP INTERCHANGE MODELS
- LOGIT MODELS
Transit trips can be generated directly, by estimating either total person trips or
auto driver trips.
DIRECT GENERATION MODELS
determine the percentage of total person or auto trips that will use transit,
estimates are made prior to the trip distribution phase based on land-use or
socioeconomic characteristics of the zone. This method does not incorporate the
quality of service
TRIP END MODELS
In this method, system level-of-service variables are considered, including relative
travel time, relative travel cost, economic status of the trip maker, and relative
travel service.
TRIP INTERCHANGE MODELS
An alternative approach used in transportation demand analysis is to consider the
relative utility of each mode as a summation of each modal attribute. Then the
choice of a mode is expressed as a probability distribution.
LOGIT MODELS
The process of allocating given set of trip interchanges to the specified transportation
system is usually referred to as
TRAFFIC ASSIGNMENT
TYPES OF TRAFFIC ASSIGNMENT MODELS
- ALL OR NOTHING ASSIGNMENT
- INCREMENTAL ASSIGNMENT
- CAPACITY RESTRAINT ASSIGNMENT
- USER EQUILIBRIUM ASSIGNMENT
- STOCHASTIC USER EQUILIBRIUM ASSIGNMENT
- SYSTEM OPTIMUM ASSIGNMENT
the trips from any origin zone to any destination zone are loaded onto
a single, minimum cost, path between them. This model is unrealistic as only one path
between every O-D pair is utilized even if there is another path with the same or nearly
same travel cost.
ALL OR NOTHING ASSIGNMENT
based on Wardrop’s first principle, which states
that no driver can unilaterally reduce his/her travel costs by shifting to another route.
USER EQUILIBRIUM ASSIGNMENT
based on Wardrop’s second principle, which states
that drivers cooperate with one another in order to minimize total system travel time.
This assignment can be thought of as a model in which congestion is minimized when
drivers are told which routes to use.
SYSTEM OPTIMUM ASSIGNMENT
is the last stage of traffic demand modeling.
TRAFFIC ASSIGNMENT
