WHAT’S NEW?

A quick guide to the new features available in Aimsun 8

October 2013 © 2005-2013 TSS - Transport Simulation Systems

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Contents

ABOUT THIS DOCUMENT 4

Copyright 4

Trademark 4

AIMSUN 8 HIGHLIGHTS 5

1. FOUR-STEP MODEL FOR DEMAND MODELLING 6

Trip Generation 6 Generation/Attraction Data Set Attribute 6 Generation/Attraction Data Set 6 Generation/Attraction Area 6 Generation/Attraction Scenario and Experiment 6

Trip Distribution + Modal Split 6 Distribution Data Set 7 Distribution + Modal Split functions 7 Distribution Area 7 Parking Area 7 Distribution Scenario 7

Public Transport Assignment 7 PT cost functions 7 Public Transport Stops 7 Public Transport Stations 7 PT Network layer and PT Sections 7 PT Assignment Scenario 8

Four-step Model 8 Four-step Model Scenario and Experiment 8

Four-step Model related objects 8 Transportation Mode 8 Time Period 8 Centroid Vector and Trip Generation/Attraction Vector 9

2. OTHER MODEL DEVELOPMENTS 10

Macroscopic model improvements 10 New Macro Assignment methods 10 User-defined function components 10 Control Plan Generator 10 Supernodes 10

Dynamic simulators improvements 11 Traffic Control statistics 11 Traffic Management statistics 11 Path statistics by vehicle type 11 Number of Vehicles missing a turning in a Replication 11

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Specific Traffic Demand for the Warmup period 11 Vehicles Generation Times saved as a Traffic Arrivals Pattern 11 Traffic Demand defined using a Traffic Arrivals Pattern 11 Flow and Flow-ALINEA meterings in mesoscopic simulations 11 New lane selection model in mesoscopic simulations 12 Optimization of threads implementation in microsimulator 12 New Giveway Model in meso and micro simulators 12 Two-way Overtaking Model 12 Adaptive traffic control systems 12

Link analysis improvements 12 Link analysis available during a simulation 12 Link analysis user interface 12

Path assignment improvements 12 Path assignment files size 12

3. PLATFORM IMPROVEMENTS 13

Traffic Profile 13

Matrix operations 13 Redistribute Operation 13 Correction Operation 13 Apply Traffic Profiles Operation 14

Matrices allow negative values 14

Graphical Outputs 14 Diagram View Style 14

3D Improvements 14

Dynamic bookmarks can be copied and pasted 14

Paste at Original Location 14

Move section objects from one section to another 14

Welcome window additional information 14

Print layout 14

4. PROGRAMMING IMPROVEMENTS 15

Microsimulator API 15 Read Pre-emption parameters 15 Time stopped in a Public Transport Stop 15 Read and set green meterings by lane parameters 15 Read Node Statistics 15 Functions relative to pedestrians 15

Scripting 15 New Python version 15 Pre-Run and Post-Run Scripts in Experiments 15

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About this document

In this document we summarise some of the key developments in version 8 of the Aimsun environment and their application to your modelling work.

Our aim is to keep you informed of any changes so that you can continue to get the best from Aimsun. As always, please be aware that product data is subject to change without notice.

TSS-Transport Simulation Systems has made every effort to ensure that all the information contained within this manual is as accurate as possible. It should be stressed however, that this is a draft version of the latest Aimsun Users’ Manual and as such, some of the contents may be subject to change..

As always, we welcome your feedback (support@aimsun.com) in our continued improvement and addition of new features to Aimsun.

Copyright

Copyright © 1992-2013 TSS-Transport Simulation Systems, S.L.

All rights reserved. TSS-Transport Simulation Systems products contain certain trade secrets and confidential and proprietary information. Use of this copyright notice is precautionary and does not imply publication or disclosure.

Trademark

Aimsun is a trademark of TSS-Transport Simulation Systems S.L. Other brand or product names included in this document are trademarks or registered trademarks of their respective holders.

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Aimsun 8 highlights

Four-step Model for Demand Modelling

Aimsun 8 introduces three main features that, together with previously existing features, complete the Four-step model that supports the Demand Modelling process at the macroscopic level:

Trip Generation Trip Distribution + Modal Split

Public Transport Assignment Each one of these features has its own Scenario and Experiment. A new global macroscopic Scenario, called Four-step Model Scenario, is available so that the user can define the whole process in an Experiment through steps in a work flow diagram.

Aimsun Expert edition and Aimsun Professional for Travel Demand Modelling edition will grant access to all the Four-step model features.

Dynamic simulation outputs

Aimsun 8 introduces new outputs in dynamic simulations related to traffic control and traffic management.

Print layouts

As a help when creating the final report for a project, from 8.0.1 onward, print layouts can

be defined prior to printing allowing to compose a graphic scene on a page, including

elements such as views of the network, legends, text, Time Series graphs or images.

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1. Four-step model for Demand Modelling Demand Modelling and Demand Forecasting are now supported in Aimsun 8 with the completion of the Four-step Model. Aimsun Expert edition and Aimsun Professional for Travel Demand Modelling edition will grant access to all the Four-step model features. A Four-step Model Scenario and Experiment collect all the steps and data interaction in the process in a work-flow diagram. The main steps in this model are:

Trip Generation

Trip Distribution

Modal Split (which in Aimsun 8 is simultaneous with Trip Distribution)

Traffic Assignment New objects like Transportation Modes, Time Periods, Vectors, Areas, Generation/Attraction and Distribution Data Sets, Public Transport Sections and Stations, Distribution + Modal Split and Public Transport functions, etc., have been added to Aimsun in order to manage all the data these new features require.

Trip Generation The Trip Generation/Attraction calculation is the first step in the Demand Modelling process. It consists in calculating the total number of trips generated and attracted by each zone (represented by a centroid in Aimsun). Results will be Generation/Attraction vectors.

Generation/Attraction Data Set Attribute The user will define the list of Attributes that will be taken into account for the Generation/Attraction process.

Generation/Attraction Data Set A Generation/Attraction Data Set must be created for each set of Census or Socio-economic data that we want to make available in Aimsun. A G/A Data Set applies for a Centroid Configuration and consists of a list of G/A Data Set Attributes. From 8.0.1 onward, an Import folder has been added to the Generation/Attraction Data Set, in order to read the corresponding zonal data from a file.

Generation/Attraction Area Zones are classified by the type of Generation/Attraction Area. All zones of the same Area Type share the same Generation/Attraction factors for the process execution.

Generation/Attraction Scenario and Experiment The Generation/Attraction process is managed by a Scenario and its corresponding Experiment. It will be executed for a particular Time Period, the selected Purposes and Transportation Modes, and with the selected Generation/Attraction Data Set as input data.

Trip Distribution + Modal Split Trip Distribution + Modal Split is the next step after Trip Generation. Distribute the trips in the Generation/Attraction vectors into O/D Matrices.

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Distribution Data Set Socio-economic data used in Trip Distribution will belong to a Distribution Data Set.

Distribution + Modal Split functions These functions model the resistance to make a trip with each of the available Transportation Modes. They give a friction factor used to distribute total trips among O/D pairs.

Distribution Area Zones are classified into Distribution Area types and a Distribution + Modal Split function is paired with each Distribution Area.

Parking Area Parking restrictions and costs are given for each area, and each zone belongs to a different Parking Area.

Distribution Scenario The Distribution + Modal Split process is managed by a Scenario where the user chooses the Time Period, the G/A vectors (which determine the Transportation Modes used), their corresponding Skim matrices (containing O/D costs) and the rest of parameters.

Public Transport Assignment In Aimsun 8, the Demand for Public Transport (PT) can be assigned. The trips in the Demand will use only the PT facilities and choose their routes using connectors from centroids to PT Stops and PT Lines, eventually making Transfers between lines.

PT cost functions In a PT Trip, there are several costs to account for. A pedestrian will leave the centroid through a connector, then wait at the PT Stop, then enter a PT vehicle paying a fare, then spend some time in-vehicle, then maybe make a transfer, walk, wait again, etc. All these steps have a cost and Aimsun 8 has newly defined functions to model them:

PT Waiting Time function (time at the stop)

PT Boarding function (fare)

PT Delay function (in-vehicle time)

PT Transfer function (transfer penalty)

Public Transport Stops The Public Transport Stop editor in Aimsun 8 includes a new tab folder (Model) which contains information related to the Public Transport Assignment: the Waiting Time and Boarding functions to be used, and walking times from this PT Stop to any other in the network.

Public Transport Stations This new object groups a set of Public Transport Stops and contains information on connection times and walking times. Connection times, when specified, will override the waiting time for the following line to be boarded when making a transfer.

PT Network layer and PT Sections When defining PT Lines as usual, in Aimsun 8, for each segment of line between one stop and the next one, a PT Section will be automatically created as well. PT Sections are afterwards

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editable, and contain the cost for the in-vehicle time in that segment, that is, a PT Delay function must be selected for each PT Section. Also, a new layer to which the PT Sections will belong, called PT Network, will be automatically created. This layer must be active in order to see the PT Lines and PT Assignment graphical results.

PT Assignment Scenario The PT Assignment is managed by its own Scenario, which contains the algorithm parameters.

Four-step Model

Four-step Model Scenario and Experiment A Four-step Model Experiment, contained in a Four-step Model Scenario, can be used to manage the whole Four-step Model process. The user can define the input data and which experiments to execute. Each box in the diagram is related with an input or a process (experiment) to be executed. The user can choose to execute the processes up to a certain point in the diagram, or a single box (provided all the previous necessary steps have been already executed).

Four-step Model related objects Transportation Mode A new object is available in Project->New->Demand Data->Transportation Mode. A vehicle type belongs to one Transportation Mode.

Time Period A new object is available in Project->New->Demand Data->Time Period.

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Centroid Vector and Trip Generation/Attraction Vector In addition to O/D Matrices, now vectors are also supported in a Centroid Configuration. We have also defined a new container for Generation/Attraction outputs: the Generation/Attraction vector, which consists of two columns: one for Generation Values and one for Attraction Values.

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2. Other model developments

Macroscopic model improvements Aimsun 8 enjoys improved assignments results (for user-defined components). We have also developed more efficient storage of the paths information. Aimsun Expert, Aimsun Advanced and Aimsun Professional for Travel Demand Modelling editions will grant access to all the Macroscopic model features. We have integrated the following enhancements into Aimsun’s macroscopic modelling capabilities:

New Macro Assignment methods Apart from the already available Frank & Wolfe method for the Equilibrium Traffic Assignment, we have introduced some other methods Aimsun 8:

All-or-Nothing Assignment: this method looks for the shortest paths in free flow and returns free flow costs and paths.

Incremental Assignment: in this kind of assignment, it is the user who fixes the % of trips that will be loaded to the new calculated shortest paths and discharged from the rest of the previous paths at each iteration.

MSA Assignment: this method is similar to Frank & Wolfe except that the step lambda is not optimised but fixed to 1/n where n is the iteration number.

Stochastic Assignment: this method is recommended for bicycle assignment. It takes into account the flows obtained in another macro experiment, calculates the k-shortest paths and assigns demand to them based on a utility function.

User-defined function components In Aimsun 7, the function components in VDF and TPF were already introduced, through the use of 4 key words (tTime, distance, vToll, fToll). When defining a subfunction by any of these names, a new column in the Assignment’s Outputs folder was created, with the values of the subfunction for each section or turning, the same in the Path Assignment folder with the paths values and skim matrices. In Aimsun 8, the list of components is not restricted to these four words; users can create their own list of key words and they will generate new outputs when the corresponding subfunctions are defined in the used functions. Also, derived components can be defined (for example, if we created a component TravelTime and a component Distance, we can define another component Speed as a derived component Distance/TravelTime and there is no need to declare it in the function when the first two are already there.

Control Plan Generator A Control Plan (fixed or actuated) can be calculated based on the results of a static traffic assignment for one or several nodes. Also, on a single intersection the control plan can be calculated based on flows entered manually by the user.

Supernodes In order to represent complex junctions and roundabouts in a more realistic way, the concept of Supernodes has been introduced. This new object represents one or more nodes and allows to define Turn Penalty Functions and Junction Delay Functions for each movement of the Supernode. After a Macro Assignment the statistics of each movement of a Supernode can be consulted and represented in the same way as for a Turn.

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Dynamic simulators improvements Aimsun Expert, Aimsun Advanced, Aimsun Professional Micro, Aimsun Standard and Aimsun Small editions will grant access to the Microscopic Simulator features. Aimsun Expert, Aimsun Advanced and Aimsun Professional Meso editions will grant access to the mesoscopic features. Aimsun Expert and Aimsun Advanced editions will grant access to the Hybrid simulator features.

Traffic Control statistics Microscopic, mesoscopic and hybrid simulations give outputs about the traffic control at each intersection. Those outputs include green time and green percentage by signal group, by turning and by phase. For actuated control plans the activation and deactivation reason are also gathered.

Traffic Management statistics Microscopic, mesoscopic and hybrid simulations give outputs about the vehicles affected by any traffic management action. It is now possible to analyse how many vehicles have been rerouted, forced a turning movement, …

Path statistics by vehicle type Microscopic, mesoscopic and hybrid simulations give now outputs about the paths used in a simulation by vehicle type. In previous versions of Aimsun these outputs where only given by vehicle type when the costs were by vehicle type. In Aimsun 8 they are available for any dynamic simulation.

Number of Vehicles missing a turning in a Replication Microscopic, mesoscopic and hybrid simulations give as a global output the number of vehicles that have missed a turning in the whole network. In previous versions of Aimsun this output was only available at a node level.

Specific Traffic Demand for the Warmup period Microscopic, mesoscopic and hybrid simulations can have a traffic demand for the warm-up period different than the first part of the stationary period traffic demand as it used to be.

Vehicles Generation Times saved as a Traffic Arrivals Pattern Information about the simulation time when vehicles were generated during a microscopic, mesoscopic and hybrid simulation can now be stored to be later on used as an input for another dynamic scenario.

Traffic Demand defined using a Traffic Arrivals Pattern The traffic demand for a microscopic, mesoscopic and hybrid simulation can now be defined using a previously stored Traffic Arrivals Pattern. These Traffic Arrivals can be combined with a set of O/D Matrices and simulation vehicles will be generated following both informations.

Flow and Flow-ALINEA meterings in mesoscopic simulations In Aimsun 8, mesoscopic simulations are allowed to simulate with flow and flow-ALINEA meterings.

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New lane selection model in mesoscopic simulations In Aimsun 8, mesoscopic simulations consider a new lane selection model that reduces stochasticity.

Optimization of threads implementation in microsimulator The implementation has been fully parallelized to substantially increase the benefits of using threads in the simulation.

New Giveway Model in meso and micro simulators The new giveway model allows a detailed calibration of the aggressiveness of the giveway for each turn.

Two-way Overtaking Model We have developed a model to simulate the overtaking maneuvers on two-lane, two-way rural roads. This model covers the desirability evaluation, decision and execution process.

Adaptive traffic control systems SCATS-RMS adaptive traffic control systems is now supported in the microscopic simulator.

Link analysis improvements Link analysis available during a simulation In Aimsun 8, link analysis is available at any point of a dynamic simulation and not only after finishing it as it used to be.

Link analysis user interface In Aimsun 8, link analysis user interface is much more faster than previous versions getting the results.

Path assignment improvements

Path assignment files size Path assignment files have been improved to reduce their size and improve the speed when loading and storing them.

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3. Platform improvements

Traffic Profile A new object is available in Project->New->Demand Data->Traffic Profile. It contains the percentages for each interval during a time period. This information will be used by the Apply Traffic Profiles operation to generate a set of O/D Matrices from a global matrix.

Matrix operations Several new matrix operations are now available:

Redistribute

Correction

Apply Traffic Profiles

Redistribute Operation An O/D matrix has a specific cost distribution based on any of its corresponding skim matrices (for example, the O/D distances matrix). After an adjustment, this distribution might have been distorted, and it can be recovered by executing a Redistribute operation that will need the following as input: the matrix to be redistributed; its current corresponding skim matrix; the original demand matrix; the original skim matrix (these last two giving the cost distribution that you want to recover).

Correction Operation This operation will apply the same (multiplicative) changes to the current matrix that were made from an original matrix to a manipulated matrix (for example, an adjusted matrix) up to a maximum correction factor.

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Apply Traffic Profiles Operation This operation will apply the traffic profiles selected per cell, obtaining O/D matrices for each interval in the profile and with values multiplied by the percentage stated in the profile.

Matrices allow negative values Matrices have been extended not to only support trips but other kind of contents such as travel times, distances, costs, … For these reason it is allowed now to input negative values in a cell.

Graphical Outputs

Diagram View Style A new View Style is available for Diagrams (with several options to choose from: Circles, Pie, Histogram or Stacked Histogram). It can be used, for example, to visualise and compare the Generation/Attraction values with a histogram for each centroid.

3D Improvements The 3D visualization has been improved with atmospheric effects such as rain or snow. Traffic lights can now be located before or after the junction. Pedestrian crossings are drawn. Furthermore, several kinds of additional file formats can now be imported. These include importing Collada files and from Google Warehouse among others.

Dynamic bookmarks can be copied and pasted Dynamic bookmarks can be copied and pasted among different networks.

Paste at Original Location Graphical objects can be copied and pasted from one network to another keeping their original coordinates, rather than always pasting them at the center of the current 2D view.

Move section objects from one section to another Section objects such as detectors, bus stops, ramp meters or VMS can now be moved using the mouse from one section to another. This is useful after cutting a section in two or when splitting a section in several sections.

Welcome window additional information The list of recently open projects in the Welcome Window informs now about the Aimsun version used to store the model, that is, Aimsun 6.1, Aimsun 7.0 or Aimsun 8.0.

Print layout From 8.0.1 onward, print Layouts can be defined prior to printing allowing you to compose a

graphic scene on a page, including elements such as views of the network, legends, text,

Time Series graphs or images. You can then print the Print Layout, or export it to a PDF or an

image.

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4. Programming improvements

Microsimulator API

Read Pre-emption parameters New functions to read the pre-emption defined for a simulation have been added to the Microsimulator API.

Time stopped in a Public Transport Stop Information about the number of seconds a Public Transport Vehicle has been stopped at a certain Public Transport Stop can now be gathered via the Microsimulator API.

Read and set green meterings by lane parameters New functions to get and set the green time by lane ramp meters parameters have been added.

Read Node Statistics Now, all information related to the node outputs such as the number of lost vehicles, delay to calculate the level of service and number of missed turns is accessible.

Functions relative to pedestrians

Two new functions to generate Legion pedestrians in a micro simulation that is simulating pedestrians with Legion for Aimsun have been included.

Scripting New Python version The scripting in Aimsun 8 requires a newer version of Python, Python 2.7.4.

Pre-Run and Post-Run Scripts in Experiments All types of experiments can automatically execute a script before the experiment is run and after the experiment has been run.