When planning a new development, transport considerations can have a significant influence on design, consenting, and the long-term operation of the site. Understanding these requirements early can help developers avoid redesigns, additional costs, and delays later in the project.

A traffic impact assessment provides the technical information needed to understand how a proposed development may interact with the surrounding transport network. It can also help identify practical solutions before potential transport issues become obstacles during the approval process.

This guide explains what a traffic impact assessment involves, when one may be required, and what developers should consider when preparing a project in New Zealand.

What Is a Traffic Impact Assessment?

A traffic impact assessment examines how a proposed development could affect the surrounding transport environment. The scope will depend on the location, scale, and nature of the development.

Rather than simply considering how many additional vehicles a project may generate, an assessment can examine site access, parking, vehicle manoeuvring, pedestrian and cyclist movements, nearby intersections, road safety, and the capacity of the surrounding network.

The findings are generally documented in a traffic impact report, providing councils and other stakeholders with clear technical evidence about the transport effects of the proposal.

Learn more about Traffic Planning Consultants' Traffic Impact Assessment service.

When Might a Traffic Impact Assessment Be Required?

Not every development requires the same level of transport assessment. A relatively small project may only require targeted advice, while a larger residential, commercial, industrial, or mixed-use development could require detailed analysis.

An assessment may be appropriate when a project is expected to generate additional traffic, alter an existing vehicle crossing, introduce a new access, change parking arrangements, or affect the operation of surrounding roads.

Council requirements and the characteristics of the site will also influence what information is necessary. Engaging a traffic engineering consultant early can help establish the appropriate level of assessment before substantial design work is completed.

What Information Is Assessed?

A traffic impact assessment begins with understanding the proposed development and the existing transport environment.

This can involve reviewing existing traffic volumes, road characteristics, nearby intersections, public transport, walking and cycling facilities, parking conditions, and existing access arrangements.

The proposed development can then be assessed against these conditions to understand how it may change travel demand or network operation.

Depending on the project, traffic modelling may also be used to assess intersections, forecast future conditions, or compare different development scenarios.

Understanding Traffic Generation

One of the key considerations is how much traffic a development is expected to generate.

Different land uses produce different patterns of vehicle movement. Residential developments, for example, generally experience different peak periods and travel behaviour from retail, industrial, or education facilities.

Traffic generation estimates help determine whether additional vehicle movements can be accommodated by the surrounding network and whether further analysis or improvements may be required.

Importantly, the assessment should consider the characteristics of the actual development rather than relying on traffic numbers in isolation.

Site Access and Vehicle Movements

A development needs to provide safe and practical access for the vehicles expected to use it.

A traffic assessment may consider the location and width of vehicle crossings, sight distance, turning movements, loading requirements, internal circulation, and interactions with pedestrians and cyclists.

Vehicle tracking can be particularly useful for testing whether cars, trucks, service vehicles, or emergency vehicles can manoeuvre through the proposed layout.

Identifying access problems during design is considerably easier than discovering that a driveway, loading bay, or garage does not function properly after construction.

Traffic Planning Consultants provides broader traffic engineering support for access and site design.

Parking and Loading Requirements

Parking can have a major influence on both site design and project economics.

A transport assessment can consider expected parking demand, the proposed number and layout of spaces, accessible parking, bicycle facilities, loading areas, and how vehicles circulate between these facilities.

The appropriate solution will depend on the development and its location. Providing more parking is not automatically better, particularly where space could be used more productively.

For some developments, travel demand management can help manage private vehicle demand and support alternative ways of travelling to the site.

Considering Road Safety

A development may comply with dimensional standards while still creating practical safety concerns.

Transport assessments therefore consider how the proposal affects different road users, including motorists, pedestrians, cyclists, and people using public transport.

Issues such as restricted visibility, complicated access arrangements, vehicle conflicts, or unsafe crossing movements should be identified before the design is finalised.

Where a project requires a more formal independent safety review, a road safety audit can examine potential risks at different stages of design and delivery.

How Traffic Assessments Support Resource Consent

Transport effects can form an important part of a resource consent application.

A clear assessment gives the relevant authority technical evidence explaining how the development is expected to operate and how potential adverse effects will be addressed.

If significant questions are left unanswered, further information may be requested during the consent process. This can create additional work for planners, architects, engineers, and other members of the project team.

Preparing the appropriate transport information early helps reduce uncertainty and gives decision-makers a clearer understanding of the proposal.

Common Traffic Issues That Can Delay a Development

Some of the most expensive transport problems are relatively simple issues discovered too late.

These can include an unsuitable access location, inadequate manoeuvring space, insufficient visibility, poorly positioned loading facilities, conflicts between vehicles and pedestrians, or assumptions about traffic generation that cannot be supported.

Resolving these matters after a design has been substantially completed can affect multiple disciplines and require significant changes.

Early traffic planning allows these constraints to be identified while the project still has flexibility.

When Should a Traffic Consultant Be Engaged?

Ideally, transport advice should begin during feasibility or early concept design.

At this stage, a consultant can identify major constraints, review proposed access arrangements, provide preliminary advice on parking and circulation, and determine whether detailed assessment is likely to be required.

This does not necessarily mean undertaking a comprehensive assessment immediately. The objective is to ensure transport considerations inform the design rather than being addressed once everything else has already been decided.

For developers, that early advice can protect both the financial viability of the project and the consent programme.

Planning for Construction Traffic

The transport impacts of a project do not begin when the development opens. Construction itself can introduce heavy vehicle movements, temporary access changes, deliveries, road closures, and additional interaction with pedestrians and surrounding properties.

Where these impacts are significant, a temporary traffic management plan may be required to establish how traffic will be safely managed during the works.

Considering construction requirements alongside the permanent design can prevent practical problems from emerging once contractors arrive on site.

Getting the Assessment Right From the Beginning

A good traffic impact assessment should do more than satisfy a consent requirement. It should help the wider project team understand how the development will function and identify opportunities to improve the design.

Early assessment can support safer access, better site layouts, more efficient parking, smoother consent applications, and fewer surprises during construction.

Traffic Planning Consultants provides traffic engineering, traffic planning, modelling, safety, and transport assessment services for developments throughout New Zealand.

Whether a project is still at feasibility stage or preparing for consent, early specialist advice can help establish the transport requirements before they become expensive constraints.

Contact Traffic Planning Consultants to discuss the transport requirements for your development.