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New features

Aimsun Next 23

New features

Aimsun Next 23

Aimsun Next 23 builds on our commitment to transportation network analysis and optimization. Many of the new features focus on efficiency with a view to enhancing the building and running of large-scale, multi-modal models for cities, highways, and regions.

The advances in efficiency are key for large-scale modeling: from reducing run times by redesigning how we manage time series, to freeing up memory by unloading results between runs, to adding the ability to evaluate cost functions in parallel. 

We’ve also introduced functionality that makes travel demand modeling more convenient, improved the microscopic and mesoscopic behavioral models, and enhanced the usage of Aimsun Next as a testing and simulation tool for traffic signal controllers.

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What’s new in Aimsun Next 23

01 Improved handling of time series

Large-scale modeling

We have redesigned the way time series are internally managed, which should significantly reduce the runtime and the time it takes to close a model after running it or retrieving the outputs of a past run.

02 Unload results from memory

Large-scale modeling

You can unload results before starting another run, to free up memory and therefore preventing pagination, thus reducing the runtime with large models.

03 DUE outputs to monitor convergence and stability

Large-scale modeling

The Dynamic User Equilibrium (DUE) assignment can output a comprehensive set of statistics that allow you to monitor in detail both the convergence and the stability of the solution: RGap by OD pair, flow and cost by link per iteration. These outputs are extremely valuable during the calibration of the model.

04 More flexibility when warm-starting a DUE

Large-scale modeling

In previous versions, a Dynamic User Equilibrium (DUE) could only load a single path assignment item generated by either a static assignment or a DUE with the same route choice interval. In Aimsun Next 23, a DUE can take as input a path assignment plan containing multiple static and/or DUE path assignment items.

Both DUE and Stochastic Route Choice (SRC) can now load path assignment items whose warm-up duration and/or route choice intervals don’t match the current dynamic traffic assignment (DTA): in DUE the percentages in the input path assignment are aggregated into the new intervals, while in SRC the vehicles following the input paths use the intervals of the path assignment item.

05 Monitor how the adjustment changes the prior demand

Large-scale modeling

The OD adjustments now provide all the outputs required by UK DfT’s TAG to monitor the changes to the prior demand brought about by the adjustment process: trip length distribution with mean and standard deviation, scatter plot of trip ends, scatter plot of cell values, and sector to sector differences.

06 Lane selection model for roundabouts

Behavioral models

We have developed a new lane selection model for roundabouts in microscopic, mesoscopic and hybrid simulations. The model calculates the valid lanes for vehicles approaching a roundabout (within look-ahead distance from the entry turn) by taking into account which exit the vehicle wants to take. This capture the fact that in reality vehicles taking the first exit tend to use the outer lane, while vehicles taking the last exit tend to use the inner lane.

07 Look-ahead for yield and stop signs

Behavioral models

The visibility distance of a yield or stop sign can now extend to upstream sections. In previous versions it was truncated at the entrance of the section with the sign.

08 Acceleration aggressiveness in the MFC model

Behavioral models

The Microscopic Free-flow aCceleration (MFC) model now includes the parameter acceleration aggressiveness, which is what defines a driver’s driving style and gear-shifting (only used with combustion engines). This allows you to decouple the acceleration behavior from the car-following headway.

09 Read the skims directly from a path assignment result

Travel demand modeling

A new box called Path Assignment can be added to four-step experiments. This allows you to use any path assignment produced from a Transit Assignment or Static Assignment to feed the Four-Step model with skims without creating skim matrices.

10 Calculate free-flow skims with the shortest path calculator

Travel demand modeling

The Shortest Path tool now has the option to generate and save cost and distance skim matrices for a given Centroid Configuration. In previous versions you had to run an assignment to get these skims.

11 Run part of the four-step model

Travel demand modeling

You can now run a single step of the four-step experiment, or a step and all the ones using its outputs. This is particularly useful during calibration or when running tests, as you can run just a portion of the experiment.

12 Save loop outputs in the four-step model

Travel demand modeling

The four-step model experiment loop results can now be stored in the database. This option allows you to restore loop results without rerunning the model.

13 New stochastic static assignment algorithm

Travel demand modeling

We have replaced the Yen’s k-SP algorithm previously used in Stochastic Static Assignment with the ESX algorithm, which is faster and produces alternative paths with less overlap.

14 Graphical and protocol view with PDM, LISA and vs|plus controllers

OCIT traffic signal testing and simulation

OCIT is an open standard for road traffic control systems. All OCIT controllers (Yutraffic, LISA and vs|plus) support graphical and protocol views, both in manual testing and in simulation.

15 Interactive change of signal program and OCIT flags with PDM, LISA and vs|plus controllers

OCIT traffic signal testing and simulation

All OCIT controllers (Yutraffic, LISA and vs|plus) support changing signal plan and change of OCIT flags both interactively for manual testing and programmatically via the master control plan or a control plan change traffic management action.

16 Push button actuations from pedestrians

OCIT traffic signal testing and simulation

Crosswalks can be associated to push buttons and when pedestrians are waiting at them, they generate actuations that are passed to the OCIT controllers.

17 Different signal groups and actuations by pedestrian type

OCIT traffic signal testing and simulation

You can define multiple signal groups at the same crosswalk for different pedestrian types, and define multiple push buttons at the same crosswalk for different pedestrian types. This allows testing and simulation of OCIT controllers that have dedicated phases and detectors for visually impaired people.

18 Serial and parallel calling points with PDM controllers

OCIT traffic signal testing and simulation

In the Yutraffic controller you can now define that a detector should behave as Serial Reporting Point or as a Parallel Reporting Point. A Serial Reporting Point sends an R09 telegram when a transit vehicle is first detected while a Parallel Reporting Point sends a presence while any equipped vehicle is on top.

19 Cost functions in Lua

Usability

To reduce the computation time when evaluating the cost functions, they can now be written in Lua, which supports multi-thread evaluation. Python is still supported as an alternative language, and the cost functions in the template are now available in both Python and Lua.

20 “Fast access” script

Usability

To allow faster execution of a Python script, one of the available scripts in the Scripts folder can be set as Fast Access script, which can be then executed using the shortcut [Ctrl + J].

21 Split a centroid automatically

Usability

The Split Centroid tool can now decide automatically the number of split centroids to generate by looking at the existing connections. The logic will generate centroids with at most one connection per direction.

22 Filter by grouping when restoring a Real Data Set

Usability

The Real Data Set dialog allows you to restore data just for objects belonging to a grouping.

23 Traffic demand histogram

Usability

A new Traffic Demand Histogram tab shows the number of cells with different ranges of number of trips. It can be plotted for all vehicles or by vehicle types, and the ranges are configurable.

24 Combine traffic states for vehicles with OD matrices for pedestrians

Usability

You can now add pedestrian OD matrices to a traffic demand with traffic states for vehicles. This allows running a pedestrian simulation when you don’t have OD matrices for vehicles.

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Cite Aimsun Next

 

Aimsun Next 23

Aimsun (2023). Aimsun Next 23 User's Manual, Aimsun Next Version 23.0.0, Barcelona, Spain. Accessed on: July. 19, 2023. [Online].
Available: https://docs.aimsun.com/next/23.0.0/

 


 

Aimsun Next 20.0.5

Aimsun (2021). Aimsun Next 20.0.5 User's Manual, Aimsun Next Version 20.0.3, Barcelona, Spain. Accessed on: May. 1, 2021. [In software].
Available: qthelp://aimsun.com.aimsun.20.0/doc/UsersManual/Intro.html
 

Aimsun Next 23

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address = {​​​​​​​​​​​​​​​Barcelona, Spain}​​​​​​​​​​​​​​​,
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Aimsun Next 20.0.5

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PB  - Aimsun
UR  - [In software]. Available: https://docs.aimsun.com/next/23.0.0/


Aimsun Next 20.0.5

TY  - COMP
T1  - Aimsun Next 20.0.5 User's Manual
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ET - Aimsun Next Version 20.0.5
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Y2 - Accessed on: Month, Day, Year
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UR  - [In software]. Available: qthelp://aimsun.com.aimsun.20.0/doc/UsersManual/Intro.html