Transport Assessment and Modelling

Transport Impact Assessment (TIA)

TIA is a process of compiling and analysing information on the impacts a development or infrastructure proposal may have on roads and transport networks.

The assessment includes general impacts relating to transport management, such as road efficiency and safety. It also considers specific impacts on all road users, including on-road public transport, pedestrians, cyclists and heavy vehicles.

Guidelines

The ACT TIA Guidelines provide practitioners and stakeholders involved in land-use  and transport planning a reference document for managing TIAs resulting from land-use development proposals. The guidelines aim to promote a common understanding of the process aligned with the national transport management guidelines. They can be tailored to the ACT’s statutory requirements, policies and strategies.

While the Austroads Guide to Traffic Management Part 12: Integrated Transport Assessments for Developments provides guidance on how a TIA should be undertaken, the ACT TIA Guidelines focus on what is required. Specifically, they aim to:

• outline the necessary matters to be considered in a TIA and provide a more transparent process
• ensure that sustainable transport goals and strategies are incorporated into the TIA process
• provide development thresholds to indicate when larger development proposals need a TIA.

The 2025 updated ACT TIA Guidelines are now available on the Standards, codes and guidelines page.

Data request and fees

From 1 July 2023 fees were introduced for transport and traffic data related requests. These fees are published on the City Services website.

Please email your request for data to TCCS.DCDevelopmentCoordination@act.gov.au. We will provide a link to the online application form where payment for the data request can be made. Following receipt of payment, we will notify you via email that your data request has been assigned to a project lead who will commence processing your request.

For information on timeframes for processing data requests, please see General Advisory Note 07 (PDF 331.1 KB).

Links

Austroads Guide to Traffic Management Part 12: Integrated Transport Assessments for Developments

ACT Traffic Microsimulation Modelling Guidelines (PDF 1.3 MB)

Guidelines for SIDRA Analysis (PDF 331.1 KB)

ACT Government ACTmapi

Canberra Strategic Transport Model (CSTM)

The CSTM is the overarching strategic transport model for Canberra. Its primary function is to forecast travel demand for future land use and infrastructure scenarios and to provide estimates of traffic growth for operational models.

The CSTM is a trip-based 4-step multi-modal transport planning model hosted in TransCAD platform. It simulates where Canberrans are moving to and from based on trip purposes and land use, how Canberrans make the trips using generalised costs and trip propensities (e.g. by car, public transport and/or bicycle), and which routes of the network Canberrans are likely to take.

The CSTM was recalibrated based on 2016 ABS Census demographic and journey to work data, updated trip rates from the 2017 Household Travel Survey and traffic conditions. It comprises base case model scenarios for 2016, 2021, 2026, 2031 and 2041. In addition to ACT districts, it covers the NSW districts of Queanbeyan to the east and Yass Valley to the north.

The model simulates peak traffic based on assumptions including land-use (population, employment, retail space and enrolments), transport network (road, public transport, and bicycle) and transport cost parameters (parking, fuel costs and bus fares).

The basic CSTM outputs include volume-capacity (congestion) plots, plots showing forecast AM (8:00-9:00) and PM (5:00-6:00) peak volumes of car traffic, public transport passenger volumes and bicycle volumes in various model years, and origin-destination matrices by trip purposes and mode.

CSTM Enhancements and Recalibration

In early 2022 we commissioned CSTM Enhancement Stage 1 to progress model improvements. These include:

• CSTM input data updates (zone structure and land use, transport networks – roads, public transport, park and ride, active travel, and cost parameters (value of time, parking costs)
• assignment improvements – volume delay functions, multi-class traffic assignment  presenting traffic flows per trip purpose, and capacity constrained PT assignment
• updated model validation

At present, a recalibration of the CSTM based on 2023 conditions including the ABS Census demographics and journey to work data and travel trends based on 2022 Household Travel Survey is underway. The CSTM Recalibration and Enhancement Project is anticipated for completion by the first half of 2024.

Household Travel Survey Dashboard

The CSTM has been recalibrated using data from the 2017 ACT Household Travel Survey. The survey collected information about how, where and when members of a selected household travel over a single day.

A total of 1,785 households and 4,611 people in the ACT and Queanbeyan contributed to the survey and completed a travel diary for a single specified day.

The survey outcomes help inform transport planning and policy development for the ACT and Queanbeyan area.

A 2022 Household Travel Survey completed in August 2023, inform the recent CSTM recalibration. A total of 2,078 households and 5,106 people in the ACT and Queanbeyan contributed to the survey.

Data request and fees

From 1 July 2023 fees were introduced for transport and traffic data related requests. These fees are published on the City Services website.

Please email your request for data to TCCS.DCDevelopmentCoordination@act.gov.au. We will provide a link to the online application form where payment for the data request can be made. Following receipt of payment, we will notify you via email that your data request has been assigned to a project lead who will commence processing your request.

For information on timeframes for processing data requests, please see General Advisory Note 07 (PDF 331.1 KB).

Links

2017 ACT and Queanbeyan-Palerang Household Travel Survey

2022 ACT and Queanbeyan-Palerang Household Travel Survey

Mesoscopic/Microscopic traffic models

While strategic transport models inform forecast travel demand for the whole transport system, operational traffic models consider detailed vehicular movement and their impacts on the road network operation. These includes mesoscopic, microscopic and intersection models.

Operational models use travel demand forecast data from the Canberra Strategic Transport Model (CSTM). They simulate the movement of individual vehicles through the road transport network either by public transport (light rail and/or buses) or cars.

They include information on:

• the road transport network
• traffic controls (including intersection controls, parking, traffic signal, control timing and coordination)
• the number of vehicle trips Canberrans make by motorised modes in peak periods.

City and Inner North Reference Model (CINRM)

The CINRM is a hybrid mesoscopic and microscopic model. Its primary function is to simulate detailed traffic impacts at a local level. This helps to inform infrastructure planning including development approvals, engineering design and community consultation.

CINRM is a detailed digital representation of the road transport network of the City and Inner North. It is based on the earlier City to Woden (C2W) model developed for the Canberra Light Rail Project with updated zoning boundaries aligned with CSTM.

CINRM was calibrated to 2019 conditions, with demand from the CSTM updated to reflect a 2019 base year model. It also has corresponding future year model scenarios for 2021, 2026 and 2031. This enables assumptions to be reflected as single source of truth and for individual project cases to be better understood. The main CINRM outputs include traffic flow, traffic delay, level of service and travel times within the City and Inner North for each reference model.

The model represents the weekday AM (7:15-9:15) and PM (4:15-6:15) two-hour peak periods. The model run involves a 15-minute warming/cooling period and a 30-minute shoulder period at each side of the peak hour. While the AM peak hour of 8:00-9:00 am is the same for CSTM and CINRM, CINRM shows a more detailed PM peak hour of 4:45-5:45 pm compared to CSTM’s PM peak hour of 5:00-6:00 pm.

Woden Valley Reference Traffic Model (WVRTM)

The WVRTM comprises base year 2021 and future year 2026 and 2031 reference models for morning and afternoon peak hour traffic periods. The WVRTM aims to support a place-based approach and assessment of the ACT Government’s delivery sequencing of transport infrastructure in the wider Woden Valley precinct.

These reference models include the future traffic growth and committed infrastructure projects such as the Light Rail Stage 2B between Commonwealth Avenue and Woden Town Centre.

The WVRTM has expanded to include:

• the Athllon Drive Duplication project
• the Light Rail extension to Mawson
• the proposed Athllon Drive high density development of 645 dwellings outlined in the 2024-25 Land Release Program.

The expansion of the study area further south was to capture the travel route choice patterns to and from the far southern suburbs such as Tuggeranong, Gowrie and Wanniassa.

Gungahlin Reference Traffic Model (GRTM)

The GRTM comprises a base year model calibrated to 2022 conditions and future base year models for 2026 and 2031. The GRTM aims to provide the ACT Government with accurate and simulation-based road and intersection performance outputs as forecast traffic volumes, travel times, queue lengths and congestion delays.

The GRTM will assist assessment of land use and transport impacts. It will inform evidence-based infrastructure planning and prioritisation of road network upgrades. This includes intersection signal configuration improvements required to accommodate development intentions in Gungahlin.

Guidelines

The ACT Traffic Microsimulation Modelling Guidelines (PDF 1.3 MB) provide guidelines on model development, calibration and validation, and documentation of results. They also provide guidance on input parameters, calibration, and validation criteria, expected outputs, and the required reporting structure.

The guidelines aim to facilitate an easier and more systematic process to assess microsimulation model quality and model outputs. This helps to ensure that traffic models and reports produced by different people or organisations will achieve a certain level of consistency that is acceptable to the Directorate.

Data and SCATS (Sydney Coordinated Adaptive Traffic System)

Data Provision

As part of the transport impact assessment process, the Directorate supports development proponents by providing:

• transport data from actual surveys and the Sydney Coordinated Adaptive Traffic System (SCATS)
• strategic transport model (CSTM) outputs
• SCATS traffic signals operation
• and mesoscopic/microscopic reference traffic models (CINRM, WVRTM and GRTM).

Both CSTM and mesoscopic reference traffic model outputs include congestion plots and traffic volumes and associated link characteristics (number of lanes, speed, capacity). They also both include underpinning land use data (population, employment, retail space and enrolments) and future road network improvements assumptions. Whereas, the SCATS data includes traffic volumes, traffic signals phasing operation and associated intersection parameters.

The proponent may need to undertake further transport modelling. This could include microsimulation and intersection modelling to meet the desired requirements to support the proposed development in the project scenario.

Please note that if the traffic study is related to the ACT Government project, the data will be provided free of charge. For non-ACT Government project related studies, data requests will be charged as per the fee rates outlined on the City Services website.

If the proposal is not for a project on behalf of the ACT Government, please direct your enquiry to Roads ACT via Access Canberra 13 22 81 or trafficsignals@act.gov.au.