Ultimate CAD Solutions

Emme provides a uniquely flexible, open approach to modeling that allows users the freedom to leverage established techniques or create novel methods to address local needs. Emme is built to handle the rigors of complex transport systems; to account for the diverse technological, social and economic challenges facing planners today. Emme wraps these capabilities with a full-featured framework for analysis, visualization, and automation.

Emme offers efficient, robust algorithms that have earned a reputation as the gold standard in transport modeling. INRO pioneered the application of both equilibrium assignment and integrated multimodal assignment, and continues to develop innovative modeling methodologies to meet the evolving needs of Emme users.

Planners depend on the reliability of Emme models. Automation has been a critical component of Emme since inception, and INRO’s commitment to backwards compatibility has enabled planners to reliably reproduce model results for more than two decades.

Instead of fixed demand modeling procedures, Emme provides a comprehensive and flexible set of tools for matrix manipulations.

The matrix calculator evaluates algebraic and logical expressions which combine scalars, origins and destination vectors, and full matrices.
The two and three dimensional balancing procedures are perfect tools for implementing various spatial interactions or trip distribution models.
A powerful tool performs generalized “matrix-product” like operations, involving intermediate zones. It may be used to implement trip chaining models, such as park-and-ride, and for many other applications.

Emme can be used to implement virtually any zonal level travel demand forecasting model, from the classical 4-step model to multimodal assignment with direct demand functions, as well as aggregate demand models based on trip chains.

Trip generation and attraction models require zonal data, which can be stored in the Emme data bank, in the form of origin or destination matrices:

Population characteristics: places of residence, dwelling types, age,
Economic activities: number of jobs, type of industry, office surface area,

Any trip generation/attraction model can then be implemented using the matrix calculator, by evaluating expressions involving zone-based data. The required coefficients are obtained, using statistical software, by calibrating models such as econometric models, category analysis,

If necessary, productions and attractions can be balanced to each other by using the matrix calculator. For example, attractions can be normalized to productions by first computing the total number of trips produced and attracted, and then multiplying the attraction vector by the appropriate ratio.

Such inputs include production and attraction vectors, as well as an input matrix.

For a Fraters or growth model (also referred to as scaling), the input matrix would be the base year O-D demand matrix.
For a gravity model, the input matrix would be the desired deterrence function.
For an entropy model, the input matrix would contain the appropriate negative exponential values. A macro can be used to calibrate the value of the (theta) parameter; for example, the value that reproduces an observed average travel time.

In the case of multiple production types, each with its own friction matrix, and a single attraction type, the 2-dimensional balancing can be carried out using the BALMPROD macro.

Three-dimensional balancing can be used to implement refined versions of distribution models, which include an additional constraint: in addition to the productions and attractions, a third set of totals is satisfied. This makes it possible to implement a model that reproduces a given travel time distribution, or a set of screen line counts, etc.

Using three-dimensional balancing, one can obtain the friction factors for each trip category considered (for example, for each travel time interval). These friction factors can then be used as a look-up table. Alternatively, an external program can be used to fit the curve corresponding to these friction factors, by using a functional form chosen by the user.

There is no default mode choice model built into Emme: the user is free to implement any model formulation, using the matrix calculator. The model can be as sophisticated as the user wants. Many different mode choice models have been successfully implemented in Emme, including hierarchical logit models which use log-sum computations. However, the desired model should be calibrated using appropriate statistical or econometric software, which is not provided with Emme.
Parking costs can be incorporated easily, using the matrix calculator. For example, the parking cost value for each destination can be kept in a destination vector which can be added to an O-D impedance matrix.