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Introduction

This section provides guidance for assessing road improvement activities with an implementation cost over $1 million per activity. These activities target a specific increase in levels of service as part of a roading network.

Guidance for the assessment of low cost, low risk improvement activities costing less than $1.0 million to implement is provided separately.

For general information about developing an assessment profile including relevant reference frameworks, see Developing an assessment profile.

 

Prior requirements for assessment

Before an investment proposal is assessed against the Investment Assessment Framework (IAF), a business case must be developed, which the Transport Agency assesses to ensure it: 

  • is robust and has been developed using business case approach (BCA) principles
  • meets the requirements for being included in the National Land Transport Programme (NLTP) and is eligible for NLTP funding.

The activity must be included in a regional land transport plan (RLTP).

For further information about prior requirements, see Developing an assessment profile.

Results alignment

For road improvement activities, the results alignment can be low, medium, high or very high (see below).

For further information on results alignment assessment see Developing an assessment profile which includes definitions of terms used. Definitions of high and medium crash risk are provided below.

 

  • Requirements for a low rating

    A road improvement activity may be given a low results alignment rating if the activity addresses one or more of the following criteria:

    Strategic priority Criteria for a low rating
    Safety
    • Addresses safety gaps with reference to the One Network Road Classification (ONRC)
    Access – thriving regions, liveable cities
    • Addresses identified resilience gap or impediments to accessing social and economic opportunities
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  • Requirements for a medium rating

    A road improvement activity may be given a medium results alignment rating if the activity addresses one or more of the following criteria:

    Strategic priority Criteria for a medium rating
    Safety
    • Addresses safety issues presenting a medium crash risk, affecting communities subject to medium safety risk, and/or in Safer Journeys area of medium concern
    Access – thriving regions
    • Addresses an identified gap in an approved regional economic development (RED) programme
    • Addresses a significant resilience gap or impediment to access on regionally important social and economic connections
    • Supports priority elements in agreed integrated land use and multi-modal plans in regions
    • Makes best use of key corridors that prioritise regional freight and tourism
    • Provides operational efficiencies to reduce the costs of meeting appropriate levels of service without impacting benefits adversely
    Access – liveable cities
    • Addresses significant gap in access to social or economic opportunities
    • Address identified gap in access to new housing in medium-growth urban areas
    • Addresses identified resilience risk to continued operation of the network
    • Addresses significant gap in integrated intermodal and user information, and significant deficiencies in network operation
    • Provides operational efficiencies to reduce the costs of meeting appropriate levels of service without impacting adversely on benefits
    Environment
    • Enables reductions in environmental and public health harms, particularly arising from land transport-related air pollution, noise, and impact of construction and ongoing use of transport infrastructure on water quality and biodiversity
    • Addresses long term reductions in greenhouse gas emissions from land transport
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  • Requirements for a high rating

    A road improvement activity may be given a high results alignment rating if the activity addresses one or more of the following criteria:

    Strategic priority Criteria for a high rating
    Safety
    • Addresses safety issues presenting a high crash risk, affecting communities subject to high safety risk, and/or in Safer Journeys area of high concern
    • Addresses safety issues presenting a high societal consequence risk
    Access – thriving regions
    • Enables a significant regional economic development opportunity in an approved RED programme 
    • Addresses significant resilience gap or impediment to access on nationally important social and economic connections
    • Addresses a gap in an approved RED programme in high priority RED regions
    • Makes best use of key corridors that prioritise national freight and tourism
    • Provides significant operational efficiencies to reduce the costs of meeting appropriate levels of service without impacting adversely on  benefits
    Access – liveable cities
    • Supports high priority elements in agreed integrated land use and multi-modal plans
    • address significant gap in access to new housing  in high-growth urban areas
    • Addresses a significant resilience risk to continued operation of the network
    • Makes best use of key corridors that prioritise multi-modal use and freight
    • Provides significant operational efficiencies to reduce the costs of meeting appropriate levels of service without impacting benefits adversely
    Environment
    • Addresses significant reductions in environmental and public health harms, particularly arising from land transport-related air pollution, noise, and impact of construction and ongoing use of transport infrastructure on water quality and biodiversity
    • Addresses long term significant reductions in greenhouse gas emissions from land transport.
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  • Requirements for a very high rating

    A road improvement activity will only be given a very high results alignment rating if the activity addresses one or more of the following criteria:

    Strategic priority Criteria for a very high rating
    Safety
    • Implements a speed management approach focusing on treating the 10 percent of the network that will result in the greatest reduction in deaths and serious injuries (DSI)
    • Targets areas of high collective risk with high DSI reduction measures that achieve a DSI reduction of at least 40% .
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Cost–benefit appraisal

The Transport Agency requires approved arganisations and the Transport Agency (state highways) to use the Transport Agency's Economic evaluation manual procedures and templates to determine the benefit–cost ratio (BCR) for road improvement activities.

Non-monetised benefits and additional benefits should also be considered where appropriate.

For further information on cost–benefit appraisal including calculating the BCR and resulting rating see Developing an assessment profile.

 

Safety risk definitions for results alignment

Risks change over time, and up-to-date trends should be monitored to ensure safety programmes are addressing the biggest risks. 

See Safety risk definitions for results alignment for details.

 

Resilience thresholds for results alignment

The Transport Agency has set threshold levels for investment activities to address resilience. These take into account the expected duration and frequency  of the road closure, the road's classification and any alternative routes. These thresholds can be used to determine when it is appropriate to propose investment activities to overcome resilience problems.

 

  • Route closures and results alignment

    Results alignment is based on the number of route closures.

    The table of acceptable closures provides the annual rate [note 1 below] for each road class when there is a viable alternative route. If there is no viable alternative route [note 2 below] the acceptable number of closures in the table  is decreased by a factor of 2.5 (ie for a regional or arterial road the number of acceptable closures becomes 4 instead of 10 closures per year for the two to four hour closure period).

    The resilience gap for results alignment is:

    o    low if all values of the number of road closures are lower than the values shown in the table (adjusted for whether a viable alternative route exists)

    o    medium if one or two values are greater than or equal to the values shown in the table (adjusted for whether a viable alternative route exists)

    o    high if three or more values are greater than or equal to the values shown in the table (adjusted for whether a viable alternative route exists).

    Notes:

    1. Average values are taken over at least a five-year period
    2. A viable alternative route is defined as:
      1. unlikely to be affected by the same or related event that disrupts the availability of the original route
      2. available to all vehicles (including high productivity motor vehicles)
      3. has the capacity to carry the volume of traffic diverted from the original route
      4. the additional travel time is no more than two hours.
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  • Table of acceptable closures

    The table below shows the acceptable number of road closures per year for ONRC road classes when there is an alternative route.

     

    Closure period

    ONRC  classification

    National high volume

    National

    Regional/

    arterial

    Primary/secondary collector

    Access/access low volume

    2–4 hrs

    1

    4

    10

    19

    30

    5–12 hrs

    0.5

    2

    5

    9.5

    14.8

    13 hrs–2 days

    0.2

    1

    2

    3.8

    5.9

    3–5 days

    0.1

    0.2

    0.5

    0.9

    1.5

    6–14 days

    0.04

    0.08

    0.2

    0.4

    0.6

    15–49 days

    0.02

    0.04

    0.10

    0.19

    0.30

    50–120 days

    0.01

    0.01

    0.025

    0.047

    0.074

    More than 120 days

    0.004

    0.004

    0.010

    0.019

    0.030

     

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Mitigation of road-traffic noise

Structural mitigation can be considered when road-traffic noise levels, as predicted by strategic mapping undertaken in accordance with the Guide to state highway noise mapping [PDF, 729 KB] (Draft) November 2013, exceed 65dB LAeq(24hr) at protected premises and facilities (PPF).

The criteria for road-traffic noise mitigation are:

  • the number of PPF exposed to road-traffic noise above 65 dB LAeq(24hr)
  • the number of PPF that would benefit from the mitigation.

Definition of PPF

PPF is defined in NZS6806:2010(external link). PPFs in urban areas should be located at a distance of less than 100m from the edge of the road seal. PPFs in rural areas should be located at a distance of less than 200m from the edge of the road seal.

Road particulates

The assessment methodology for road particulates provides a risk rating of low, medium or high.

To determine the risk rating, use the following tables:

  1. Table 1: Use this to assess whether there is a need to mitigate road dust for a particular section of road. The dust risk score is calculated by totalling the scores for each of the 11 individual factors.
  2. Table 2 : Use this to calculate the site dust risk score which will fall into one of three dust risk categories. Table 2 provides a first order assessment of the potential benefits gained by mitigating a section of unsealed road and indicates what action (if any) is needed to complete the decision-making process.

 

  • Table 1: Site dust risk factors and scores

     

    Risk factor/score

    0

    1

    2

    3

    4

    5

    Traffic

    5-day annual average daily traffic (AADT) of HCVs*

    0

    1–5

    6–10

    11–25

    26–50

    More than 50

    Speed limit of HCVs* (km/h)

    No HCVs

    20km/h

    50km/h or greater

     

     

     

    5-day AADT of LCVs**

    Less than 100

    101–300

    More than 300

     

     

     

    Speed of LCVs** (km/h)

    Less than 50

    50–70

    Greater than 70

     

     

     

    Receptors (within 80m of roadway)

    Number of dwellings (houses/km)

    0

    1

    2–4

    5–7

    8–10

    More than 10

    Other locations where people are likely to be exposed (eg schools, marae, or hospitals) (sensitive locations/km)

    None

    1–2

    3 or more

     

     

     

    Ecologically sensitive areas such as rare species habitats or wetlands (sensitive locations/km)

    None

    1–2

    3 or more

     

     

     

    Horticultural sensitive areas such as fruit orchards (sensitive locations/km)

    None

    1–2

    3 or more

     

     

     

    Site characteristics

    Location of roadway

    Open plains or costal area

    Some land features likely to slow winds

    Inland enclosed valley

     

     

     

    Frequency of rain days (> 5mm)

    More than 2 events per week

    0–1 event per week

    Less than one event every 2 weeks

     

     

     

    Longevity of logging route use

    Not a logging route

    1–2 years

    Longer than 3 years

     

     

     

    Notes:

    *HCV  =  heavy commercial vehicle (vehicle with gross vehicle mass greater than 3,500kg). Research report 590 uses HDV which has been amended to HCV to reflect sector terminology.

    **LCV  =  light commercial vehicle (vehicle with a gross vehicle mass of less than 3,500kg). Research report 590 uses LDV which has been amended to LCV to reflect sector terminology.

    Calculations use a five-day average of the AADT from Monday to Friday

     

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  • Table 2: Risk category and actions

     

    Total dust risk score

    Dust risk category

    Potential benefit from dust mitigation

    Action to be taken

    0–9

    Low risk

    Little or no benefit from mitigation

    End of decision-making process

    10–19

    Medium risk

    There may some benefit from mitigation

    Return to and repeat the ‘Site dust risk factors and scores’ with refined site-specific information

    20–38

    High risk

    There is likely to be a benefit from mitigation

    Complete assessment of suitable mitigation options

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  • Reference for dust risk assessment

    The Transport Agency research report 590, Impacts of exposure to dust from unsealed roads, provides a methodology to assess the level of health risk associated with individual unsealed roads. Undertaking an assessment using this methodology produces a numerical output which can then be used to determine the relative level of risk of harm to human health from unsealed roads. Approved organisations can also reference the National Environmental Standards (NES) for particulates which cover road dust, vehicle emission particulates, tyre dust, etc.

    Research report 590 uses HDV and LDV which have been amended to HCV and LCV to reflect sector terminology.

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