View all publications

6 Tier 1 Preliminary Assessment

The Tier 1 assessment is a qualitative assessment. The objectives are to compile background information, identify key issues and determine the appropriate level of assessment. It is recommended that a Tier 1 preliminary assessment be undertaken at the beginning of a project, before the design phase, and before consultation with the regional council or other interested parties.

The Tier 1 assessment should consider the receiving environment and the nature and scale of the proposal, focusing on the:

  • scale of the development

  • alternatives

  • airshed designation under the Standards

  • existing air quality

  • physical geography of the receiving environment

  • sensitivity of the receiving environment

  • any relevant objectives, policies or rules in the regional or district plan.

These factors are discussed further below. The level of detail required will vary depending on the proposal. Some projects that are unlikely to result in significant increases in emissions will not require a Tier 2 or 3 assessment. Section 6.1 suggests thresholds to identify these projects, as well as basic reporting recommendations.

For projects that require further assessment, the main purpose of the Tier 1 assessment is to identify key issues early in the process. For significant projects a preliminary assessment may allow options to be ranked. The important point is that air quality issues be identified and addressed as early as possible in the project, and a preliminary or qualitative assessment provides the opportunity to do this.

6.1 Proposals that do not require further assessment

A Tier 1 assessment will be all that is required for any project that does not result in significantly increased emissions. Table 6.1 suggests quantitative assessment thresholds to help determine whether further assessment of a project is required.

Note: an air quality assessment is not necessary for any project that will not result in a significant increase in emissions at any location.

For projects that do not require further assessment, a formal Tier 1 assessment report may not be required. Where a report is necessary (eg, to meet funding requirements), an assessment for this type of activity should include:

  • a description of the project

  • a summary of any traffic data used to determine whether further assessment is required

  • a description of the receiving environment, including air quality, topography and meteorology

  • an assessment of the sensitivity of the receiving environment, including the location of any sensitive receptors in relation to the project.

6.1.1 Suggested thresholds to determine whether further assessment is required

Table 6.1 suggests thresholds to determine whether a Tier 2 or 3 assessment is required. These thresholds are intended as a guide only: the extent of the air quality assessment is a matter for judgement. For example, even if a project is well below the suggested thresholds, it may be appropriate to undertake more detailed air quality assessment in areas where there is a high level of community concern about air quality or new roads. The basis for the suggested assessment thresholds is discussed in Appendix 1. The thresholds are conservative, and are based on limited information. There is currently no other policy or guidance available to help agencies identify projects that do not require assessment, so these thresholds have been suggested as a first step. It is likely that thresholds will change over time as practitioners become more experienced in transport assessments and the availability of project monitoring improves.

Assessment against thresholds should be undertaken for all new roading projects. For changes to existing roads or road networks, this assessment should be undertaken for all roads or links where the project is likely to result in a significant increase in emissions. The assessment will need to demonstrate that the assessment area includes all roads or links that are directly or indirectly affected by the project.

The suggested thresholds rely on estimated traffic as a proxy for air quality effects. In cases where the estimated traffic is close to the thresholds described in Table 6.1, a Tier 2 assessment should be considered, particularly if there are sensitive receptors such as residential houses, childcare or health-care facilities close to the proposal.

To assess a project against the suggested thresholds, traffic information will be required for all links and intersections affected by the project, including:

  • annual average daily traffic (AADT)

  • level of service (or average speed)

  • traffic composition (for current and future conditions, where available)

  • traffic forecasts.

In relation to the last point, the future assessment years may depend on the availability of traffic demand models, but should include a long-term forecast (at least 10 to 20 years). Where local traffic forecasts are not available, the default traffic growth rates provided by the Project Evaluation Manual (Transfund, 2004) should be used. If it is likely that the Tier 1 traffic thresholds will be exceeded in future, then a Tier 2 assessment should be considered.

Table 6.1: Suggested thresholds to identify projects that do not require further assessment

Location to be assessed

Steps to complete assessment

Notes

STEP 1: Determine whether the project requires assessment

New roads

Go to Step 2

 

Changes to traffic on existing roads due to land-use changes, or permanent changes to the road network or infrastructure

Are there any parts of the project being assessed where there will be:

  • any significant increase in traffic, or

  • any significant decrease in level of service, or

  • any significant increase in the proportion of heavy duty vehicles (> 3.5 tonnes)?

Determining whether the change is significant is a matter for judgement. If there is doubt, a Tier 2 assessment will quickly determine whether changes are significant.

Action: Proceed to STEP 2 for these projects. Projects that do not require assessment include temporary diversions, maintenance works, and any project that is not likely to increase emissions.

STEP 2: Evaluate traffic information to identify possible 'hot spots'

Busy roads

Identify links where traffic is likely to be greater than 7,000 vehicles per day.

 

Congested roads

Identify any links that may be congested, where traffic is likely to be greater than 3,000 vehicles per day.

Concentrations are often higher where traffic is slow-moving with stop/start driving. Use local knowledge and/or results of traffic modelling to identify likely areas of congestion.

Busy intersections

Identify any busy intersections with more than 7,000 vehicles per day, regardless of level of congestion.

Where two or more roads intersect, the traffic flows should be added to give a combined total.

Roads with a high flow of buses and/or heavy-duty vehicles

Identify any links where the flow of heavy duty vehicles (> 3.5 tonnes) is likely to be more than 500 vehicles per day.

 

Action: For any links or intersections identified in STEP 2, proceed to a Tier 2 assessment. If there are no links or intersections identified in STEP 2, no further assessment is required.

6.2 Information required for a Tier 1 assessment

This section describes the information requirements for a Tier 1 preliminary assessment of projects that will require further assessment.

The scale of the development

The assessment should include a description of the project, including traffic data. Relevant information to assess the scale of the development will include the amount of traffic, the level of service and the proportion of diesel vehicles. Key questions to ask include:

  • Will the project cause an increase in traffic volumes at any location?

  • Will the project change the composition of traffic or flow dynamics at any location? For example, will existing roads linked to the new project experience an increase in the proportion of heavy traffic, or an increase in the level of congested flow?

  • Is the project of sufficient scale to affect air quality across the airshed?

Alternatives

The Tier 1 assessment should consider alternatives including:

  • alternative locations that may be less sensitive

  • alternative locations for any likely hotspots (eg, intersections) that may be less sensitive

  • alternative transport schemes (eg, a different mix of road / public transport / traffic demand management).

Airshed designation under the national environmental standards for air quality

At the time of publication, 69 areas throughout New Zealand have been gazetted as airsheds under the provisions of the Standards. Of these, around 30 are likely to exceed the national ambient air quality standard for PM10 and are therefore subject to controls on the granting of resource consents. It is likely that any development within these airshed areas that shows any significant increase in PM10 emissions will require a Tier 3 assessment. For up-to-date information on airshed designations, contact the appropriate regional council.

The existing air quality

Existing air quality is an important consideration in any air quality assessment. The Tier 1 preliminary assessment should determine what information is available (if any) on existing air quality, and how this compares to relevant air quality criteria.

The physical geography of the receiving environment

The physical geography of an area can affect the dispersion of pollutants, and is a particularly important consideration in dispersion modelling. The preliminary assessment should identify whether there are any significant topographical features that may affect dispersion.

Features such as coasts and mountainous terrain require more complex predictive modelling techniques than, for example, flat inland sites. These considerations are well covered in the Good Practice Guide for Atmospheric Dispersion Modelling (Ministry for the Environment, 2004), which is a companion guidance to this document.

Plan and transport strategy requirements

The Tier 1 assessment should include a review of the relevant regional and district plans, and regional transport strategy to identify any relevant objectives, policies or rules.

The sensitivity of the receiving environment

Adverse effects on air quality can be exacerbated by the sensitivity of the receiving environment. An assessment of the sensitivity of the receiving environment requires an assessment of land use and the likely sensitivity of the local population to air emissions. Table 6.2 provides a general classification of the sensitivity of various land uses to discharges of contaminants into air. Because land uses are the key criteria for classifying the sensitivity of the receiving environment, district plan zonings can have a large influence on an area’s sensitivity. Higher sensitivity land uses will require a higher level of assessment. Key questions to ask include:

  • Are there any facilities (schools, hospitals, etc) or sensitive receiving environments located within close proximity to the project (200 m)?

  • What is the distance to these sensitive locations (or receptors)?

  • Are any of these sensitive locations (or receptors) close to potential hotspots?

Table 6.2: Types of land use/location and the sensitivity of the receiving environment

Land use

Reasons for sensitivity

Rating

Hospitals, schools, childcare facilities, rest homes

People of high sensitivity (including children, the sick and the elderly) are exposed.

People are likely to be exposed continuously (up to 24 hours, seven days a week).

High

Residential

People of high sensitivity (including children and the elderly) are exposed.

People cherish a stress-free environment at home and have the view that “my house is my castle”.

People may be present at all times of the day and night, both indoors and outdoors.

Visitors to the area are unfamiliar with any discharges and are more likely to be adversely affected (which can cause embarrassment to residents and raise awareness of the problem).

High

Open space recreational

These areas are used for outdoor activities and exercise, in circumstances where people tend to be more aware of the air quality.

People of all ages, physical conditions and sensitivity can be present.

High

Tourist, cultural, conservation

These areas can have high environmental values, so adverse effects are unlikely to be tolerated.

High

Commercial, retail, business

These areas have a similar population density to residential areas as people of all ages and sensitivity can use them.

Commercial activities can also be sensitive to other uses (eg, food preparation affected by volatile organic compounds emissions from paint manufacture).

There can be embarrassment factors for businesses with clients on their premises.

Medium to high

Rural residential / countryside living

Population density is lower than in residential areas, so the opportunity to be adversely affected is lower. However, people of high sensitivity can still be exposed at all times of the day and night.

Often people move into these areas for a healthier lifestyle and can be particularly sensitive to perceived health risks.

Medium to high

Rural

A low population density means there is a decreased risk of people being adversely affected.

People living in and visiting rural areas generally have a high tolerance for rural activities and their associated effects. Although these people can be desensitised to rural activities, they are still sensitive to other types of activities (eg, industrial activities).

Low

Heavy industrial

Adverse amenity effects tend to be tolerated as long as the effects are not severe.

Many sources discharge into air, so there is often a mix of effects.

People who occupy these areas tend to be adult and in good physical condition, so are more likely to tolerate adverse effects, particularly if the source is associated with their employment.

Low

Light industrial

These areas tend to be a mix of small industrial premises and commercial/retail/ food activities. Some activities are incompatible with air quality impacts (such as paint sprayers requiring a dust-free environment), while others will discharge to air.

Low

An air quality assessment is not necessary for any project that will not result in a significant increase in emissions at any location.

A Tier 1 preliminary assessment should be undertaken at the beginning of a project.

A Tier 1 assessment will be all that is required for any project that does not result in significantly increased emissions at any location. Table 6.1 provides suggested thresholds to identify these projects. Note, however, that these may be superseded as more information becomes available.

If there is any doubt, the assessment should proceed to Tier 2, or be discussed with the regional council.