What Is a Traffic Impact Assessment?

You will encounter both terms. Historically, development assessments often focused heavily on traffic generation, road capacity, parking and vehicle access, which is why “traffic impact assessment” remains widely used.

Transport for NSW now uses the term Transport Impact Assessment in its current Guide to Transport Impact Assessment.

The change reflects a broader approach to development-related transport planning that considers the movement and safety of different transport users rather than assessing a proposal only in terms of additional cars.

The current Transport for NSW guide includes guidance on:

• Multimodal transport network impacts.
• Site access and design.
• Travel demand management.
• Trip generation.
• Parking provision and design.
• Pedestrian and cycling movement.
• Public transport.
• Freight and servicing.
• Road safety.

Transport for NSW’s current guide superseded the Guide to Traffic Generating Developments 2002 and the Updated Traffic Surveys Technical Direction (TDT 2013/04a) from 4 November 2024.

“Traffic Impact Assessment” is not an incorrect phrase — it remains commonly used, while “Transport Impact Assessment” is the terminology adopted in current TfNSW guidance.

The scope depends on the proposed development and the level of transport impact expected.

A Transport Impact Assessment may consider:

• The location and scale of the proposed development.
• Existing transport conditions around the site.
• Future transport conditions and committed network changes.
• The number of trips the development is expected to generate.
• The modes people are expected to use to reach the development.
• When those trips are likely to occur.
• How trips are distributed across the surrounding transport network.
• Vehicle access to and from the site.
• Internal vehicle circulation.
• Parking provision and parking design.
• Loading, deliveries and servicing.
• Waste collection arrangements.
• Pedestrian access and movement.
• Cycling access and facilities.
• Public transport accessibility.
• Accessibility for people with disability.
• Car-share and electric-vehicle arrangements where relevant.
• Road-safety conditions.
• Nearby intersections, driveways and transport facilities.
• The potential effect of the proposal on surrounding transport users.
• Measures that could reduce or manage identified transport impacts.

Transport for NSW’s current guide says the level of assessment should be proportionate to the expected transport impact of the proposed development. Not every TIA must analyse every item listed above.

The exact structure depends on the development, consent authority and required level of assessment.

A Transport Impact Assessment can include:

• Background and description of the proposed development.
• Relevant planning and transport context.
• Existing land uses and transport networks surrounding the site.
• Existing and planned transport infrastructure.
• Baseline transport conditions.
• Existing road-safety conditions.
• Accessibility by different transport modes.
• Estimated trips generated by the proposed development.
• Expected mode share.
• Transport-network impact analysis.
• Site-access arrangements.
• Internal movement and circulation.
• Parking and servicing.
• Pedestrian and cycling arrangements.
• Measures proposed to manage transport impacts.
• Findings and recommendations.

Transport for NSW’s methodology treats a development within its wider transport context rather than examining the site in isolation. Nearby intersections, paths, driveways, public transport facilities and other developments can therefore be relevant to the assessment.

One important part of a transport assessment is estimating how many trips a proposed development is likely to generate. This is not necessarily the same as simply predicting additional cars.

A modern transport assessment can consider trips by different modes, including:

• Private vehicles.
• Walking.
• Cycling.
• Public transport.
• Taxi and rideshare.
• Freight and servicing.
• Other relevant transport modes.

The consultant may consider when trips occur, where they are likely to come from or travel to and how they interact with the surrounding transport network. Trip-generation assumptions depend on factors including the proposed land use, scale and location.

Transport for NSW’s current guide includes land-use trip-generation guidance but also emphasises the need for professional judgement rather than a one-size-fits-all approach.

Transport for NSW’s current guide distinguishes between a Transport Impact Assessment (TIA) and a Transport Impact Statement (TIS).

A TIA is the more comprehensive assessment.

A Transport Impact Statement can be used for a development expected to have relatively low trip generation and relatively low impact on the surrounding transport network. Transport for NSW recommends consultation with the consent authority to confirm the methodology before a TIS is prepared.

A TIS generally records factual project information such as:

• Site location and context.
• Proposed land use.
• Development scale.
• Access arrangements.
• Trip generation.
• Trip distribution.

This means a smaller development should not automatically be assumed to require the same level of technical assessment as a major residential, commercial, retail, industrial or mixed-use proposal.

Transport for NSW’s current guide should be consulted for current methodology. Do not rely on hard-coded legislative size or capacity thresholds, because planning legislation, referral arrangements and thresholds can change. Direct users to current Transport for NSW guidance and the relevant consent authority for the requirements applying to their project.

A Transport Impact Assessment is not required for every development application. The need and level of assessment depend on the development, site, access arrangements, expected transport impacts and applicable planning requirements.

An assessment may be required or useful where:

• A development is expected to generate substantial additional trips.
• A large residential, commercial, retail, industrial or mixed-use development is proposed.
• New or significantly altered vehicle access is proposed.
• The development may affect an important road or intersection.
• Parking demand or parking design requires detailed assessment.
• Loading, servicing or waste collection could affect surrounding roads.
• Significant pedestrian or cycling movements are expected.
• The development is close to major public transport or relies heavily on public transport access.
• Road-safety issues need to be assessed.
• A proposal may affect a classified road or other important transport infrastructure.
• The consent authority specifically requires a transport study.
• A planning instrument or referral requirement triggers transport assessment.

City of Sydney provides one council example. Its current document requirements include a transport impact study for certain larger residential and non-residential developments and where the consent authority considers a proposal may generate significant traffic impacts. Do not reproduce City of Sydney’s current numeric thresholds as general NSW thresholds — requirements vary between consent authorities and can change.

Some development applications require consultation, concurrence or another form of referral involving a NSW Government agency or other body. The exact process depends on the development, applicable planning legislation and the infrastructure or State interest involved.

NSW introduced a new Development Coordination Authority referral framework in 2026. The new framework consolidates referral requirements and identifies three broad forms of referral:

• Consultation.
• Concurrence.
• Integrated development.

Current referral requirements are set out through the NSW planning framework and should be checked for the particular development. See the Development Coordination Authority referral framework page for current information.

Transport for NSW’s Guide to Transport Impact Assessment remains the primary current technical guidance for preparing and reviewing transport impact assessments. Transport for NSW does not personally review every development that met an old Schedule 3 or historic referral threshold.

Traffic and Transport Impact Assessments are commonly prepared by consultants specialising in traffic engineering and transport planning. You may encounter professional descriptions including:

• Traffic engineer.
• Transport engineer.
• Transport planner.
• Traffic and transport consultant.

The appropriate expertise depends on the project and complexity of the assessment.

Larger or more complex developments can require experience in areas such as:

• Transport modelling.
• Intersection analysis.
• Road-safety assessment.
• Parking design.
• Active transport.
• Public transport.
• Freight and servicing.
• Travel-demand management.

No particular professional title is universally mandated for every TIA unless the consent authority or applicable requirement specifies it. When requesting a quote, provide the consultant with the actual council, planning or referral requirement so they can determine the correct scope and methodology.

It can, but not every assessment requires the same type or amount of survey data. Depending on the project, a consultant may need information such as:

• Intersection traffic counts.
• Vehicle turning movements.
• Parking occupancy.
• Pedestrian movements.
• Cycling movements.
• Public transport information.
• Site-access movements.
• Existing travel patterns.

The need for new surveys depends on the assessment and whether suitable current data already exists. Where new surveys are required, timing can matter. Traffic conditions during school holidays, public holidays, unusual events, major roadworks or other atypical periods may not represent normal conditions. The consultant should determine what data is appropriate for the project.

The current Guide to Transport Impact Assessment superseded the former Updated Traffic Surveys Technical Direction, so the older document should not be used as the primary current guidance.

Often, where parking is relevant to the proposed development. The assessment may consider:

• Number of parking spaces proposed.
• Parking demand.
• Parking layout and circulation.
• Accessible parking.
• Visitor parking.
• Bicycle parking.
• Motorcycle parking where applicable.
• Car-share arrangements.
• Electric-vehicle facilities.
• Interaction between parking, pedestrians, cyclists and service vehicles.

However, parking requirements are not determined solely by the Transport for NSW guide. Council development controls, planning instruments, the building use and other applicable requirements can all affect the parking assessment.

Site access is an important component of many Transport Impact Assessments.

Depending on the development, the consultant may consider:

• Driveway location.
• Entry and exit movements.
• Sight distance.
• Interaction with surrounding roads.
• Internal circulation.
• Queuing.
• Swept paths for design vehicles.
• Loading areas.
• Delivery vehicles.
• Waste collection.
• Emergency access.
• Pedestrian and cyclist conflicts.

Larger developments may also require separate documentation such as servicing plans, delivery plans, travel plans or construction traffic-management documentation. Not every one of these services is included in every TIA.

Yes, where relevant to the development and assessment scope. Transport for NSW’s current guide treats road safety as an important consideration when assessing transport impacts.

Depending on the project, this can include:

• Existing safety conditions.
• Vehicle access.
• Intersection operation.
• Pedestrian crossings.
• Cycling facilities.
• Conflicts between different transport users.
• Internal movement arrangements.
• Proposed changes to surrounding infrastructure.

Some developments may also require a separate Road Safety Assessment or Road Safety Audit. Those separate services are not automatically included in every Traffic Impact Assessment.

Transport for NSW’s current guide provides further detail.

There is no standard timeframe. The program depends on the project and the information required.

Factors can include:

• Development complexity.
• Availability of current traffic or transport data.
• Whether new surveys are required.
• The need for intersection or network modelling.
• Council or authority consultation.
• Whether road-safety work is required.
• Changes to the architectural design.
• Parking and servicing analysis.
• Whether additional scenarios need to be tested.
• Coordination with other consultants.

A relatively contained assessment using available data may be completed much faster than a large development requiring surveys, modelling and consultation. If transport surveys are required, ask when they can be undertaken and whether the timing is appropriate for representative conditions.

Providing relevant project information early can help the consultant define the correct assessment scope. Useful information may include:

• Site address.
• Current architectural plans.
• Site survey.
• Proposed land use.
• Floor areas or dwelling numbers.
• Proposed operating hours.
• Parking numbers and layout.
• Driveway and access arrangements.
• Loading and servicing information.
• Waste collection arrangements.
• Expected staffing, visitors or customers where relevant.
• Applicable planning controls.
• Council requirements.
• Pre-lodgement advice.
• Any government-agency correspondence.
• Existing traffic or parking studies.
• Project timeline.

If the council or another authority has specifically requested a TIA, Transport Impact Study or Transport Impact Statement, provide the exact wording rather than simply asking the consultant for “a traffic report”.

What is a traffic impact assessment?

A traffic impact assessment is a technical assessment of how a proposed development may affect transport conditions around a site. Current Transport for NSW guidance uses the term Transport Impact Assessment. The assessment can consider vehicle traffic as well as walking, cycling, public transport, parking, servicing, site access and road safety.

Is a Traffic Impact Assessment the same as a Transport Impact Assessment?

The terms are often used to describe similar development-assessment work, but current Transport for NSW guidance formally uses Transport Impact Assessment. The broader term reflects the fact that the assessment considers multiple transport modes rather than vehicle traffic alone. 'Traffic Impact Assessment' remains a commonly used industry and search term.

What is the difference between a TIA and a Transport Impact Statement?

A Transport Impact Statement is a less comprehensive assessment intended for developments expected to have relatively low trip generation and relatively low impact on surrounding transport networks. A full Transport Impact Assessment is more comprehensive. Transport for NSW recommends confirming the appropriate methodology with the consent authority.

Who prepares a traffic impact assessment?

It is commonly prepared by a traffic or transport consultant with relevant expertise. This may include a traffic engineer, transport engineer or transport planner depending on the project. The required expertise depends on the complexity of the assessment and any requirements imposed by the consent authority.

Do I need a traffic impact assessment for a development application?

Not always. The requirement depends on the development, location, expected transport impact and applicable planning requirements. A council or other consent authority may require an assessment for particular development types or where it considers the likely transport impacts significant.

Does a traffic impact assessment only look at cars?

No. Current Transport for NSW guidance takes a multimodal approach. Depending on the project, the assessment can consider pedestrians, cyclists, public transport, freight, servicing and other transport users as well as private vehicles.

Does a TIA include parking?

Often, where parking is relevant. A TIA may assess parking provision, demand and design, but the applicable parking requirements can also come from council controls, planning instruments and other project requirements.

Does a TIA include traffic counts?

It may. The need for new surveys depends on the project and the availability and suitability of existing data. Larger or more complex assessments may require traffic counts, pedestrian surveys, parking surveys or other transport data.

How long does a traffic impact assessment take?

There is no standard timeframe. A straightforward assessment may be relatively quick, while a development requiring new surveys, traffic modelling, authority consultation or multiple design iterations can take considerably longer. Ask the consultant for a project-specific program.

What replaced the old Guide to Traffic Generating Developments?

Transport for NSW's Guide to Transport Impact Assessment superseded the 2002 Guide to Traffic Generating Developments and the 2013 Updated Traffic Surveys Technical Direction from 4 November 2024. The current GTIA is the appropriate starting point for current NSW transport-impact-assessment guidance.

For information about when an assessment may be required, who prepares it and consultants operating in this category, see Traffic Impact Assessments.

Also see What Reports Do You Need for a Development Application?.