Introduction to Transportation Modeling
Expert-defined terms from the Professional Certificate in Transportation Modeling course at London School of Business and Administration. Free to read, free to share, paired with a globally recognised certification pathway.
Activity #
Based Model (ABM): A type of transportation model that focuses on the activities of individuals, such as work, school, and shopping, and how these activities influence their travel behavior. ABMs estimate the travel demands of individuals and households, rather than aggregating travel demand to zones or traffic analysis zones (TAZs) as in traditional four-step models.
Assigned Traffic (Link Traffic) #
The traffic volume assigned to a link or road segment in a transportation model. This value is determined through the model's assignment process, which matches travel demand to the transportation network based on the shortest path, travel time, or other factors.
Demand Modeling #
The process of estimating travel demand, including the number of trips, trip purpose, trip length, and departure time, for a given transportation system or network. Demand modeling is typically based on data from surveys, censuses, and other sources, and is used to inform transportation planning and decision-making.
Disaggregate Modeling #
A type of transportation model that estimates travel behavior at the individual or household level, rather than at the aggregate level. Disaggregate models, such as activity-based models, consider the characteristics and preferences of individual travelers, and are often more detailed and accurate than aggregate models.
Four #
Step Model: A traditional type of transportation model that consists of four main steps: trip generation, trip distribution, mode choice, and traffic assignment. The four-step model estimates travel demand, trip distribution, mode choice, and traffic flow for a given transportation system or network, and is widely used in transportation planning and decision-making.
Gravity Model #
A type of transportation model that estimates trip distribution, or the number of trips between origin and destination zones, based on the size of the zones and the distance between them. The gravity model is based on the concept of gravitational attraction, where the number of trips between two zones is proportional to the product of their sizes and inversely proportional to the square of the distance between them.
Mode Choice Model #
A type of transportation model that estimates the probability of travelers choosing a particular mode of transportation, such as a car, bus, or train, based on their characteristics and preferences, as well as the characteristics of the available modes. Mode choice models are used in the four-step model and other transportation models to estimate the distribution of travel demand across different modes of transportation.
Multimodal Modeling #
A type of transportation model that considers the use of multiple modes of transportation, such as cars, buses, trains, and bikes, in a single model. Multimodal models are used to estimate the interactions between different modes of transportation and to inform transportation planning and decision-making.
Network Model #
A type of transportation model that represents the transportation system or network as a set of nodes and links. Network models are used to estimate traffic flow, travel time, and other factors on the transportation network, and are widely used in transportation planning and decision-making.
Simulation Model #
A type of transportation model that uses mathematical and computational methods to simulate the behavior of a transportation system or network over time. Simulation models are used to estimate the impacts of different scenarios, such as changes in demand, supply, or infrastructure, on the transportation system or network.
Stochastic Model #
A type of transportation model that includes randomness or uncertainty in its calculations. Stochastic models are used to estimate the probability of different outcomes, such as travel time or traffic flow, and are often used in transportation planning and decision-making to account for the variability and uncertainty in travel demand and transportation systems.
Supply Model #
A type of transportation model that represents the supply side of the transportation system, including the infrastructure, vehicles, and operations. Supply models are used to estimate the capacity, performance, and efficiency of the transportation system, and are widely used in transportation planning and decision-making.
Trip Generation Model #
A type of transportation model that estimates the number of trips, trip purpose, and trip length for a given area, such as a zone or traffic analysis zone (TAZ). Trip generation models are based on data from surveys, censuses, and other sources, and are used in the four-step model and other transportation models to estimate the demand for travel in the transportation system or network.
Trip Distribution Model #
A type of transportation model that estimates the number of trips between origin and destination zones in a transportation system or network. Trip distribution models, such as gravity models, are based on the size of the zones and the distance between them, and are used in the four-step model and other transportation models to estimate the distribution of travel demand in the transportation system or network.
Travel Demand Modeling #
The process of estimating travel demand, including the number of trips, trip purpose, trip length, and departure time, for a given transportation system or network. Travel demand modeling is based on data from surveys, censuses, and other sources, and is used to inform transportation planning and decision-making.
Travel Time Model #
A type of transportation model that estimates the travel time for a given trip, based on the characteristics of the trip, the transportation system or network, and other factors. Travel time models are used in the four-step model and other transportation models to estimate the travel time for different modes of transportation and to inform transportation planning and decision-making.
Transportation Planning Model #
A type of transportation model that is used to inform transportation planning and decision-making. Transportation planning models include the four-step model, activity-based models, simulation models, and other types of models, and are used to estimate travel demand, trip distribution, mode choice, traffic flow, and other factors in the transportation system or network.
Transportation System Model #
A type of transportation model that represents the transportation system or network as a whole, including the infrastructure, vehicles, operations, and travel demand. Transportation system models are used to estimate the performance, efficiency, and sustainability of the transportation system, and are widely used in transportation planning and decision-making.
Traffic Assignment Model #
A type of transportation model that estimates the traffic flow, travel time, and other factors on the transportation network, based on the travel demand and the characteristics of the network. Traffic assignment models, such as the all-or-nothing model and the capacity-restrained model, are used in the four-step model and other transportation models to estimate the traffic flow and travel time on the transportation network.
Zonal Model #
A type of transportation model that represents the transportation system or network as a set of zones or traffic analysis zones (TAZs). Zonal models, such as the four-step model, are based on data from surveys, censuses, and other sources, and are used to estimate the travel demand, trip distribution, mode choice, and traffic flow in the transportation system or network.