GR5 N GR6 - TRANSPO

Travel demand forecasting

Travel demand forecasting

is the process of predicting future travel patterns and volumes to aid in transportation planning and decision-making.

Trip Generation

Estimating the number of trips that will be produced and attracted by different land uses in each area.

Trip Distribution

Determining where trips are likely to go, identifying origins and destinations.

Mode Choice

Predicting which modes of transportation (e.g., car, bus, walking, biking) will be used.

Route Assignment

Identifying the routes travelers are likely to take.

Trip Generation

It refers to the process of estimating the number of trips originating from or destined to a particular land use, such as residential, commercial, industrial, or recreational areas.

Zonal Based Model

aggregates trip generation data at a spatial level, usually dividing a study area into traffic analysis zones (TAZs).

Household Based Model

focuses on estimating trip generation at the level of individual households or types of households.

Regression Model

are statistical tools used to estimate the number of trips generated by different land uses based on observed relationships between trip-making and various independent variables.

Trip Rate Analysis

is a method used in trip generation to estimate the number of trips that a specific land use will generate based on standardized trip rates.

Cross-Classification Model

is a method used to estimate the number of trips generated by households or individuals based on their characteristics.

The FHWA Simplified Trip Production Procedure

is a method used in transportation planning to estimate the number of trips generated by different land uses, particularly in urban areas.

Trip Distribution

is a process by which the trips generated in one zone are allocated to other zones in the study area.

Gravity Model

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

The Fratar Model

the total trips for each zone are distributed to the international movements, as a first approximation, according to relative attractiveness of each movement

Mode Choice

is concerned with the trip-maker's behavior regarding the selection of travel mode. The reasons underlying this choice vary among individuals, trip type, and the relative level of service and cost associated with the available modes.

Mode Characteristics

This is a factor influencing mode choice, such as travel time, cost, and convenience, play a crucial role in the trip-maker's mode choice

Traveler Characteristics

The socioeconomic status of the trip-maker, including income, age, and access to private transportation, affects their mode choice behavior.

Trip Characteristics

The purpose and nature of the trip, such as commuting to work or a social outing, can influence the preferred mode of travel.

Utility Function

measures the degree of satisfaction that people derive from their choices. It is typically expressed as a linear weighted sum of the independent variables, such as travel time and cost.

Disutility Function

represents the generalized cost or impedance associated with each choice. It is the negative of the utility function, as people perceive travel time and cost as losses.

Attribute-Specific

This approach assumes that people perceive goods and services in terms of their attributes, which are weighted identically across choices.

Mode-Specific

This approach assigns different weights to the same attributes for different modes.

Probability Calculation

The multinomial logit model calculates the probability of choosing mode K as the ratio of the exponential of the utility of mode K to the sum of the exponentials of the utilities of all competing modes.

Independence of Irrelevant Alternatives (IIA)

states that the ratio of the probabilities of two alternatives is a function of the difference in their utilities and is not affected by the utility of any other alternative in the choice set.

Limitations

The IIA property can lead to counterintuitive results, such as the "blue bus/red bus" problem, where the introduction of a new mode with the same utility as an existing mode does not affect the shares of the original modes

The Incremental (or Pivot-Point Logit Model)

is used in situations where a base set of choices (or utilities) is already known or available, and the decision maker is making a choice based on deviations or changes from these known conditions.

Independence of Irrelevant Alternatives (IIA)

The probability of choosing between two modes is unaffected by the introduction of a third mode.

Maximum Likelihood Estimation

most common technique used to estimate logit models, which seeks to find the combination of model parameters that maximizes the likelihood of replicating the observed mode choices.

Commuting Patterns

Mode choice models are often used to understand and predict ____________, as the choice between driving, taking the bus, or using rail transit can vary significantly based on individual, trip, and mode characteristics.

Leisure Travel

Mode choice models can also be applied, the choice of mode may be influenced by factors such as cost, convenience, and the purpose of the trip.

Urban Travel

particularly important for understanding and predicting the use of public transportation, walking, and cycling, as well as the role of private vehicles

Trip Assignment

The last phase of the four-step transportation-forecasting process is concerned with the trip maker's choice of path between pairs of zones by travel mode and with the resulting vehicular flows on the multimodal transportation network.

Traffic Assignment

In this step, the estimated trips from each zone are assigned a specific transportation routes based on mode choice and available transportation infrastructure.

Person Trip

A trip by one person in any mode of transportation. This is the most basic and universal measure of personal travel.

Transit Assignment Models

are used to estimate the number of passengers that use transit segments and routes in a transit network as a function of transit level of service and fare

Vehicle Trips

A trip by a single privately-operated vehicle regardless of the number of persons in the vehicle.

Diurnal (Time-of-Day)

are used to estimate travel by hour of the day by splitting the daily demand into its hourly components

Internal-Internal Trips (I-I)

For trips that both start and end within the defined area, different factors are applied based on the purpose of the trip (e.g., commuting, shopping, recreation).

External Trips

For trips involving movement in or out of the area

External-Internal (E-I)

Trips starting outside the area and ending inside.

Internal-External (I-E)

Trips starting inside and ending outside.

External-External (E-E)

Trips that begin and end outside but pass through the area.

Trip Direction

It is desirable that the assignment of trips (especially by the time of day) retains the ·direction of these trips.

Morning Peak Travel Pattern

During the morning rush hours, most trips head toward major activity centers— places where people need to be in the morning, like workplaces, schools, shopping areas, and markets.

Evening Peak Travel Pattern

In the evening, the travel pattern typically reverses as people head away from these centers to return home or go to other destinations after work or school

Diversion-Curve Model

It is used to predict how many drivers will choose a freeway over an alternative route based on factors that affect the ease or difficulty of travel (called impedance)

Fixed Facilities

This refers to major roads that don’t change location, like arterials, expressways, and freeways. These are included in the network model, while local and minor streets are often excluded for simplicity.

Nodes

(like intersections and interchanges), each is given a unique numerical code

Links

road segments between nodes, each is described by the codes of its start and end nodes.

Nodes and Links

are used to represent the fixed facilities

Judicious Coding Scheme

helpful to assign codes to nodes in a way that reflects their type or function

Special Connections

Specific links can represent on-ramps and off-ramps that connect different road types.

Interzonal Flows

This term refers to the demand for travel between pairs of zones (denoted as I and J. it captures how many trips are made between different geographic areas or zones in a transportation network.

Link Flows

This term specifically refers to the flow of traffic on a particular link (or segment) of the transportation network, identified as (i, j). It is the sum of all interzonal flows that utilize that link as part of their route.

Uppercase letters (e.g., I, J, for zones and Q for interzonal flows)

are used to represent the broader concepts of zones and interzonal flows

Lowercase letters (e.g., i, j for nodes and q for link flows)

are used to represent specific points in the transportation network and the flows on the links connecting these points

User Equilibrium

whereupon each user goes on the shortest path

System Equilibrium

whereupon the total cost of using the system is minimized.

Stochastic Equilibrium

The way each user assigns himself or herself on a path that he or she thinks is the shortest.

Minimum Path Algorithms

The basic minimum tree algorithm begins at the node of origin and proceeds outward, successively eliminating links that clearly do not belong on any minimum path emanating from the origin

Free All-or-Nothing Traffic Assignment

allocates the entire volume interchanging between pairs of zones to the minimum path calculated on the basis of free-flow link impedances.

Capacity-Restrained Traffic Assignment

Several iterative assignment techniques address the convergence between the link impedances assumed prior to assignment and the link impedances that are implied by the resulting link volumes

Capacity-Restrained Methods

techniques that employ capacity restraints

Capacity Function

The relationship between link flow and link impedance

AUTO MOBILE OWNERSHIP

Considered as one of the key determinants of transport behavior and is included in virtually every model of trip generation and mode choice.

TRIP-GENERATION MODEL

A usual method for model estimation is regression. These are often segmented by either gender or level of automobile ownership. Common factors used are the number of automobiles available and household structure

Trip-Based Model

also commonly known as four-step models, are so called because the primary unit of analysis is the trip interchange (i.e. origin-destination pair) between two geographic locations

Journey-Based Model

refers to a method of analyzing and simulating travel patterns by focusing on complete journeys, from the starting point to the destination, rather than isolating individual segments of the trip

Tour-Based Model

arrange travel into units called tours

Tours

are travel events that start at one location and return to that same location.