9. ROAD CONSTRUCTION

SECTION 9 Code of Practice for Development TAURANGA DISTRICT COUNCIL Road Construction

0148692.01 Print Date: May 2002 VERSION 1

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9. ROAD CONSTRUCTION

MINIMUM REQUIREMENTS

9.A General 9.A.1 The road hierarchical system shall provide a clear physical distinction between each type of road based on function, convenience, traffic volume, vehicle speed, public safety and amenity. The design period for all roads within Tauranga District shall not be less than 20 years. Projected traffic flows will be made available on request. The volumes on roads in a road hierarchy vary with City size. What may be an Arterial in Tauranga may be a Collector in Sydney. Generally it is possible to decide what is a Local road and what is an Arterial or Strategic road and then to consider the rest as filling functions between the two. 9.A.2 Each development shall ensure that vehicular access is available to allotments. Associated roading shall be designed to link to the existing roading network and be capable of accommodating the projected traffic volumes and the relevant type of vehicle movements. 9.A.3 Where improvements to the existing roading network require greater than the minimum 8 metre carriageway width (or that standard which is required to serve the proposed subdivision), Council shall reimburse the consent holder for the cost of the additional works required, subject to competitive pricing, an agreed cost share and the allocation of Council funding through each Annual Plan/Budget process. 9.A.4 The functions of roads is to provide a safe, efficient and effective traffic corridor for vehicles, pedestrians and cyclists as part of the living environment. Unless the movement of vehicles is well controlled, the positive healthy living environment can soon be eroded. Roading layout designs are to incorporate methods which will foster this and hence minimise the need for retrospective installations, ie utilise speed reduction devices such as thresholds and squeeze/pinch points. (Refer TDC District Plan Sections 7.1.1.3 and 19.3.1.9)

C1 Road Heirachy Definitions (These are used in LIM and PIM reports on properties adjoining Strategic and Arterial Routes). Strategic Route State Highway managed by Transit on behalf of the Crown. Through traffic function of road predominates. Heavy vehicles higher proportion of traffic access function of minor concern. The primary function is to service large traffic volumes. Arterial Route (Regional) Arterial Route (District) Principal traffic routes between parts of a region or district which connect Strategic Routes to major traffic generators. Traffic function predominates with property access of lesser concern. Traffic volumes over 8000vpd. Collector Route Connects roads of higher hierarchy which carry traffic from local roads to Arterial Routes and Strategic Routes. Traffic function importance but property access of equal importance. Sub Collector Routes Less through traffic than a collector but still a significant traffic function as well as an access function. Local Roads Roads which predominantly cater for local residents and access to private property. Through traffic should be discouraged.



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MEANS OF COMPLIANCE

9.B General 9.B.1 Unless otherwise demonstrated and approved, the legal road width, carriageway width and grades shall be in accordance with Drawing R1. Any road to be vested in Council must have a minimum legal road width of 12m.

The consent holder should be aware that additional road reserve widths may be required for particular intersection treatments. These widths may not be able to be determined at resource consent stage and hence any resource consent approval does not pre-empt the need for any boundary adjustments at engineering drawing approval stage. 9.B.2 To consider how a road carriageway width may be determined, the following need to be taken into account: 1 likelihood of opposing traffic. 2 likelihood of parking on both sides of the road continuously. 3 likelihood of vehicles turning into driveways. 4 Space for cyclists. The standard Austroads lane width is 3.5m. In multi-landed roads or confined urban areas widths as narrow as 2.8m can function satisfactorily if the transitions are managed and there are no vehicle entries from them. The standard parking lane is 2.5m, the standard flush median 3.0m and the cyclist lane 1.5 to 2.0m. The following table forms the basis for the widths in the Tauranga Code. Also refer R1 – “Access Criteria”.



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Local Street (over 30 households) [access both sides] Approx 300 – 2000 vpd

8m 1 thru lane and 1 parking lane and 1 cyclist

Sub Collector (through Road serves 200 lots or more) [access both sides] Approx 2000 - upwards

10m 1 parked car, 1 cyclist, 2 thru lanes or 2 thru lanes, 2 parked cars

Collector (through Road) [access both sides]

12m to 15m

2 parked cars, 2 thru lanes, or 1 parked cars, 2 cyclists, 2 through lanes

Arterial Roads and Strategic Roads [access both sides]

15m to 19m

2 parked cars, 2 cyclists, 2 thru lanes, 1 turning median

9.B.3 Early consideration is to be given to streetscape in the determining of the roading layout design to ensure that landscaping is adequately provided for at the outset.

9.C Geometrical Design

9.C.1 Gradients of all roads shall comply with those shown in Drawing R1. In particular cases, steeper gradients may be permitted over short lengths, but Council reserves the right to impose special conditions of construction. Grades shall be as long as possible with vertical curves provided to comply with Austroads “Guide to Traffic Engineering Practice” and “Rural Road Design Guide to Geometric Design of Rural Roads”. Wherever practicable the gradient within 30m of intersections on local streets should not exceed 10% and should preferably be less than 3%.

9.C.2 Normal crossfall shall be 3% for urban roads, and 4% for rural roads in both directions from the crown. However, when widening an existing carriageway or in steep terrain, crossfalls may vary from 2% to 4% in urban roads, and 5% in rural roads from the crown, coupled with a lateral shift in crown position of up to one quarter of the effective road width. Single crossfall carriageways will be permitted.



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9.C.3 Super-elevation shall be applied to curves on all roads where the speed environment exceeds 70kph and to approved arterial roads and shall be calculated using Austroads ‘Rural Road Design Guide to the Geometric Design of Rural Roads’ Zoning Road Type Max Super. Urban 12m carriageway and above 3% Rural All roads exceeding 400m 7%

9.C.4 The minimum longitudinal grade of kerb and channel shall be 1 in 200 and be parallel on both sides of the road other than on transitions into super-elevation. 9.C.5 Minimum horizontal curve radii shall be designed to reflect the intended road use and anticipated traffic speed.

C1 On occasions flatter gradients may be approved on application in specific cases to Group Manager of City Services C2 Where radii are to be restricted application is to be make to Group Manager of City Services

Horizontal curves in urban zones may be circular with a minimum centerline radius of 80m for all industrial streets, subcollector, collector and primary streets. For local streets the radius may be reduced progressively to a minimum of 15m as the traffic volume decreases. Extra widening is required on curves whose radii is less than 60m. This is assessed at between 0.5m to 1.5m and the road reserve width may need to be increased accordingly.

Reverse curves are to be separated by a length of straight as set out in Austroads “Guide to Traffic Engineering” or “Rural Road Design” to allow for a satisfactory rate of super-elevation reversal.

At intersections the kerbline shall be as on Drawing R22 and cul-de-sac turning circles conforming to Drawing R4. Specific design will be required at major intersections and round-a-bouts to meet the tracking curve requirements as set out in ‘New Zealand On Road Tracking Curves’ published by LTSA October 1995.



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9.C.6 The standard formation, crossfall and position of services is as detailed on Drawing R2. Variations from standard crossfall may be permitted, in steep terrain or when widening existing carriageways, in accordance with the Table below. Berm crossfalls in excess of 5% will be considered on a specific design basis with site access subject to individual design.

Max range of crossfall Berm 2% -20% Footpath 2%

C3 NZS 4121:1985 stipulates a 2% footpath crossfall. Any variation from this will require specific approval. It is envisaged that this will achieve a practical solution.

9.C.7 Cut and fill batters to roads shall be constructed within private property with a maximum grade of 1:5, commencing at the road boundary. Where circumstances dictate a steeper grade is necessary a geotechnical assessment of the slope shall be provided together with specific access design. Any retaining wall designed to support the road or footpath shall be constructed within the road reserve.

9.C.8 Where road marking and signage are required as an integral part of the roading function, it is the consent holders responsibility to provide these facilities.

9.C.9 As part of the engineering plan approval, satisfactory design drawings for signs and road markings are to be prepared in accordance with the following documents:

• Manual of Traffic Signs and Markings (TNZ/LTSA) Part I and II Traffic Signs Edition 3, 1995

• Transit NZ-P/12, Specification for Pavement Markings: April 1994.

Council will arrange the necessary authority for the works and engage at the consent holders expense an approved contractor should the consent holder not wish to undertake to install the signage.



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9.D Structural Design of Pavement 9.D.1 All roads shall be designed as structural pavements to have a minimum performance life of 20 years before major pavement reconstruction may be necessary. It is recognised that as a result of wear and tear, loading and natural occurrences, resurfacing to maintain the pavement condition may be required within the design life. For various surface types, an indicative life cycle time period (based on historical data) is shown in Figure 9.D.1.

Surfacing Type Use Category - VPD (From TDC RAMM Tables) 1 2 3 4 5 Vehicles per day VPD <100 100-499 500-1,999 2,000 -

10,000 >10,000

Lifecycle Years:Historical Data

MULTI APPLICATION TYPE Initial waterproofing First Coat Seal (grade 4 or other) 2 1 1 1 1 Secondary coats or otherwise Slurry Seal 10 8 6 4 3 Grade 5 Seal 10 10 8 6 6 Grade 4 Seal 14 12 10 10 7 Grade 3 Seal 16 14 12 10 8 Grade 2 Seal N/A N/A N/A 10 8 Thin Asphaltic Concrete 16 16 16 14 12 SINGLE APPLICATION TYPE Twin Coat Grade 3/5 Seal 15 12 10 10 N/A Concrete or Clay pavers 20

(expected) 20 (expected)

20 (expected)

N/A N/A

Figure 9.D.1

The intent of roadway pavement design shall be: • To achieve a structurally sound pavement to prevent punching

shear, horizontal shear, delamination and surface rutting. • To achieve a finished surface stiffness which ensures that the

pavement design life and surfacing performance indicators will be met.

• To achieve an aesthetic surface that does not produce excessive tyre noise.



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Adequate attention to, and measurement of subgrade performance together with specified unbound pavement aggregates complying with the Transit New Zealand Ltd (TNZ) standard specifications that will provide adequate pavement strength. The consent holder shall provide test results to show that the correct assessment of the subgrade characteristics and appropriate pavement design has been made to produce a surface stiffness that meet the requirements of this code.

9.D.2 The following information shall be submitted in conjunction with the engineering design drawings for approval.

• All soil test information obtained to provide a basis for pavement design, with a reference to origin of design method. Important aspects for consideration are the soils density, moisture content, and shear strength. Where substantial cuts and fill are anticipated, the range of CBR’s are to be aligned with the Geotechnical Investigation Report. Final design shall be confirmed at subgrade approval.

• Copy of design calculations used to determine pavement thickness.

When a stabilising agent is to be used, the designer shall submit a range of relevant test results, and calculations, including the percentage use of the stabilising agent and an indication of the likely CBR value to be achieved by the stabilisation.



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9.D.3 Roadway Pavement Design Processes All new and reconstructed roads shall be designed in accordance with: − Austroads Pavement Design

• a Guide to the Structural Design of Road Pavements 1992 • supplementary ARR6 Report number 21 - design of new

pavements for light traffic • Transit New Zealand Supplement November 1995

and all subsequently issued amendments. Design of roads by other methods is permitted only with the consent of the Group Manager of City Services. Where alternative design processes are proposed, consent to adopt the design method shall be “project specific” and be obtained prior to approval and shall include: • The basis of the pavement design approach and technical

references in support of its use. • Commentary as to the reasons that the Austroads Pavement

Design is not used. • An outline of site data collection and schedule of field laboratory

testing to be undertaken as appropriate. • An outline of design and construction compliance with the

pavement stiffness characteristics given in section 9G. Acceptance or non-acceptance of the design proposal will be made on a “project specific” basis.

9.D.4 Specific Design The pavement design is based on the subgrade strength and an assessment of the effects that Traffic Loading will have on it. The design process based on road types shall be:

ROAD TYPE DESIGN PROCESS DESIGN MANUAL Cul-de-sac CBR (%) on surface Austroads supplement - Local Road deflection control Design of new Sub Collector (distributor)

and design traffic ESA’s pavements for light traffic

Industrial/ Commercial Road

Interlayer strain analysis by CIRCLY

Austroads 1992 - Structural Design of

Principal / Collector Arterial Road

Road Pavements



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ESA’s/lane are to be assessed on the number of allotments served by the road. The initial construction traffic and the traffic once in use is to be included in the calculation of the number of ESA used for design. The ESA/lane shall be assumed for each road considered for conformation with the category adopted. Where the ESA/lane exceeds that assigned to each road category the next higher class of road shall be used.

C4 New design (Australia) ESA is ‘Equivalent Standard Axle’ which refers to a transmitted load of 80kN. Old design (New Zealand) EDA is ‘Equivalent Design Axle’ which refers to a transmitted load of 8.2 tonne.

Refer to Drawing R5 for a CBR based pavement process. Refer to the Austroads - “Pavement Design” for design process using interlay strain analysis. Design by surface deflection control is a permitted alternative to mechanistic design by the CBR method. Designers shall establish the stiffening characteristics of sub base and basecourse aggregate and shall specify sufficient thickness to achieve deflection characteristics on the surface of the basecourse in compliance with Section 9G of this Code.

An indication of the stiffening affects of unbound aggregate is: Estimated Deflection On Surface (mm)

Subgrade Deflection

(mm)

Thickness of Unbound Aggregate

150mm 200mm 300mm 400mm 500mm 2 1.6 1.4 1.1 <1.0 3 2.3 1.9 1.5 1.2 1 4 2.9 2.45 1.8 1.4 1.25 5 3.5 2.8 2.1 1.7 1.4 6 4 3.3 2.4 1.85 1.55

Subgrade characteristics for pavement design are not determined until landform earthworks are undertaken. For the purposes of engineering approval assumed values can be applied based on judgement and experience on the basis that confirmation tests and/or assessments are made to confirm the design when the pavement subgrade is exposed. Tauranga District Council shall be notified when the subgrade testing/assessments are to be made. Designers shall establish their own criteria for design and determination of unbound aggregate thickness for a deflection based design process. The table above is only a guide.



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9.D.5 Determination of Subgrade Characteristics In the Tauranga District there are basically two predominant soil types: − sands − volcanic ash. Designers shall be fully conversant with the sensitive nature of the volcanic ash soils when subjected to traffic loading and shall take full account of these characteristics in designing pavement thicknesses. Important factors are: • The site soil/fill soil subgrades will be subjected to intensive

construction traffic loads. Volcanic Ash soils remould, lose shear strength and become more flexible with repeated trafficking.

• The Volcanic Ash Soils have an ability to substantially regain shear strength and stiffness where, after remoulding, they are left in an un-trafficked state. The time durations to achieve regain of strength and stiffness varies according to the nature of the Ash, its water content and permeability.

• Measurement of the subgrade soil characteristics whether by deflection of CBR shall reflect the disturbed remoulded characteristic.

• The CBR value shall be determined by soaked laboratory tests or field tests.

• Scala Penetration Test derived CBR parameters by reference to ad hoc relationships between these properties are not to be used as the only determining correlation for use in pavement design.

• Soil uniformity between points of measured CBR and deflection values is to be determined by Pilcon Shear Vane performed at depth 125mm below the subgrade surface. Peak and remoulded undrained shear strength shall be measured and appropriate statistical analysis undertaken to identify the design characteristic set by the status of the road. See table below.

C5 Choice of the correct subgrade characteristics with correct design and detailing and quality assurance of pavement construction should achieve the basecourse surface deflection criteria.



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9.D.6 Subgrade Improvement Where the designer wishes to use stabilisation as a method of design or where the existing subgrade is of a low bearing value and the designer wishes to strengthen it, it may be advantageous to stabilise the subgrade or the sub-base. The minimum depth to be stabilised shall be not less than 150mm. The equivalent CBR value obtained from the stabilised soil tested in the Laboratory and in situ shall be used for design to determine the overlying aggregate thickness. Alternatively, the designer may wish to improve the subgrade by undercutting and replacement with a better quality selected material. A geofabric may also be required to separate the subgrade from the selected layer if the subgrade is likely to contaminate it. Specific design to include the effect of the geotextile may be used if this can be substantiated by a measured improvement in subgrade strength.

9.D.7 Pavement Unbound Granular Material • Two basecourse quality types are required: Quality Size Code (1) Transit New Zealand All passing 40mm TNZ M/4 (AP40) (2) General Quality All passing 40mm GAP40 The GAP 40 specification limits recommended are:

Grading: Upper grading limits as for M/4 Lower grading limits 5% below the M/4 levels

Crushing resistance (10%): Not less than 11 tonne Weathering resistance: C.B. or better Sand equivalent: Not less than 25

Local variants of the above parameters may be approved by the Group Manager of City Services. Principal, Collector and Heavy Industrial Road Pavements shall

ROAD TYPE CHARACTERISTIC VALUE %LCV Cul-de-Sac Local Road

CV=µ + 1.3S 90

Sub Collector CV = µ + 1.65S 95 Industrial Commercial Road

CV = µ + 2S 97.5

Collector & Arterial CV = µ + 2S 97.5

µ = average S = standard deviation LCV = less than characteristic value



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utilise TNZ M/4 (AP40) in at least the upper 100mm layer. The remainder of the basecourse layer may be G.A.P40. Culdesacs, local roads. Local Through Road joining culdesac and short roads to Sub Collectors (serving 200 household units or more). Min widths 20.0, 10.0, grade 8.33%. Road Function – Local access to areas some through function. Connects to Secondary Network. • Where sub-base is required it can be a lower strength durable

material but must be capable of carrying the imposed loads without significant change. It shall be free of organic matter.

Grading: within broad limits the grading in the sub-base layer is not important. 9.D.8 Pavement Construction Construction shall be inaccordance with Transit New Zealand B2 specifications. The basecourse surface shall be inspected for shape before any surfacing. Basecourse shape shall be measured in relation to the lip of the channel. The tolerances of final level for the basecourse shall be:

At centreline and near pavement edge At channel Asphalt -5mm to +15mm -5mm to +5mm Two Coat Seal -5mm to +15mm 0mm to +10mm

Note: where asphalt is to be placed, the top of basecourse shall be the asphalt depth below the final level. The standard of smoothness of the completed basecourse shall be such that there is no point in the surface that varies more than 12mm from a 3m straight edge laid parallel to the centreline of the road (except within a vertical curve section) and from a cross section camber board placed at right angles to the centreline. Design consideration excepted, no area of the completed surface shall have any depression that will cause water to pond. Prior to sealing, any loose or caked material shall be removed and the surface shall be swept clean. At the time of sealing the surface shall be clean, dry, uniform, tightly



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compacted and shall present a stone mosaic appearance 9.D.9 65mm diameter under channel drains shall be installed where groundwater conditions dictate, along kerb lines, including medians, roundabouts and traffic control islands, as shown on Drawings R6, R8 and R9. Additional subgrade drainage may be required as identified in the Geotechnical Investigation Report.

9.D.10 Where wet/soft areas are encountered during road construction at or below subgrade level, suitable drainage shall be provided connecting to the under channel system. Extensive areas requiring drainage shall be subject to special design with appropriate input from the geotechnical engineer. In such areas consideration should be given to the use of a suitable geotextile cloth.

9.E Kerbing and Sumps

9.E.1 Kerb and channel as shown on Drawing R6 shall be provided on both sides of the carriageway in all urban subdivisions. Continuous poured concrete kerbing with at least a 28 day strength of 17.5Mpa may be used. Additional care is required during construction to prevent damage to kerb edges. Any ponding of water in the channel shall render the work unacceptable. Mountable kerbing as detailed in Drawing R6 may be used on roads where services utilities are located clear of the roadway.

9.E.2 Sumps shall be constructed as on Drawing R9 unless approved otherwise by Group Manager of City Services in which case sumps as shown on Drawing R10 may be used. Sumps shall be located as follows:

• On roads having a carriageway up to and including 11.0m at generally maximum channel run of 100m and on all roads with carriageways greater than 11.0 shall have a maximum channel run of 80m.

• On the high side of intersections, located at the kerbline tangent point.

At changes of gradients or direction in the channel where there could be a tendency for water to leave the channel.



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• A double sump to minimise the risk of ponding shall be provided at cul-de-sac ends where there is a low point and at lowest point in sag vertical curves.

• Where longitudinal gradients of the road exceed 12% sumps shall be located at maximum of 80m intervals

• Having regard for future vehicle crossing locations. 9.E.3 Sumps shall be connected to the primary stormwater system by a 225mm minimum diameter (300mm diameter, for double sumps) connection to an adjacent manhole. If the adjacent stormwater system is of greater size than 600 diameter and the manhole is not conveniently located, the sump lead may be saddled directly to the pipe. Individual sumps or interconnected double sumps shall be connected separately to the manhole

9.E.4 Stormwater connections from properties will not be permitted into mountable kerb and channel.

9.F Footpaths and Crossings and Berms

9.F.1 Footpaths shall be provided on both sides of the street (as per drawing R2) where the carriageway width is greater than 9 metres. For all other roads / streets at least a single footpath shall be provided.

9.F.2 The footpath shall be generally of concrete, 1.4m wide with a minimum 28 day strength of 17.5MPa and with a minimum thickness of 100mm on a compacted subgrade. Footpaths are to be clear of all obstructions, i.e., light standards, street and traffic signs. Extra widening may be required at the request of the Group Manager of City Services.

C7 Arrangements should be made early for the installation of services with the relevant network utility operators to avoid damage to footpaths, berm grassing and the like by late installation

9.F.3 Footpaths in industrial and commercial areas will be constructed by Council after the building development has taken place. To this end, the consent holder shall pay to Council such a sum of money as may be determined by the Group Manager of City Services to cover the cost of a concrete footpath as per Clause 9.F.2. The consent holder’s development work will allow for the



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construction of a verge between kerb and boundary at a cross fall of not less than 2% and covered with 25mm of topsoil over clay/pumice subgrade, 50mm topsoil over sand subgrades and sown is grass.

9.F.4 A pram/wheelchair crossing as detailed on Drawing R14 shall be provided at all road intersections and such other locations as to provide for logical and safer movements of pedestrians. The maximum gradient for any pram crossing shall be l in 12 (8.3%)

9.F.5 Vehicle crossings shall be provided as detailed on Drawing R12 and R13 as per Council’s vehicle crossing policy, where the vehicle entry point has been defined at construction drawing stage. Vehicle crossings shall be installed by the consent holder where any lot has a parking bay on the frontage or where the location of crossing is limited or controlled by the presence traffic islands or other feature.

9.F.6 After formation, footpath and kerb and channel works have been completed, the berms shall be spread with a 100mm loose depth (50mm depth after rolling) of topsoil. The topsoil shall be graded from kerb top to footpath edge and must not cause a ridge at the footpath that could tend to hold water on the surface of the path. The berms shall be sown with a perennial Rye/Clover mixture grass seed, to establish a quality grass cover.

C8 In sandy conditions the minimum depth of topsoil is 150mm (after rolling)

9.G Carriageway Acceptance

9.G.1 A Registered Engineer experienced in the design of pavements is to certify that the completed pavement has been constructed in accordance with Transit New Zealand B2 specifications and that is has sufficient strength and stiffness to meet the requirements of the Code of Practice. The certification shall be in the format given on Drawing R29 (2pgs). The certification is to emphasise that any final surfacing with Asphaltic Concrete meets the design intent given under section 9.D of this code.

C9 The Benkleman Beam Test is not

9.G.2 Acceptance of the certification by Tauranga District Council will be on the basis of Section 9.G.1 in conjunction with

used as the definitive compliance test however it is used as a uniformity test and provides detection for remedy of excessive deflection and



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observation monitoring as detailed in Section 1.L.5(b). In addition bowl shape deflection testing on the surface of the basecourse layer is to be undertaken. It is intended to determine that the surfacing can tolerate the measured deflection ratio characteristics without fracturing and fatiguing in less than the resurfacing time given in table 9.D.1. The bowl deflection is to be a bowl deflection based on a D250/D0 ratio using a Standard Benkleman Beam Test method to measure pavement deflections. For all streets which are to have an asphaltic concrete surface the parameters of surface stiffness are of paramount importance. The table below is to be utilised for this purpose:

verifying design criteria where deflection method is used for design of pavement. Normal professional rank shall be taken by the certifier to ensure that the required stiffness of the carriageway is achieved relative to its designated purpose. Should due diligence not be forthcoming stricter parameters may be imposed in the future.

95 Percentile Bowl Ratio D250/D0 Road Type/

Asphaltic Thickness

Cul-de-Sac Local Road

Subcollector Industrial/ Commercial

Principal Road Arterial Road

25mm 0.54 0.54 - - 40mm - - 0.65 0.65 By Specific

Design 50mm - - 0.70 0.70

These values are a guide only and may be modified by Tauranga District Council as more definitive data is produced. Designers are permitted to:- • Include modifiers to the asphalt mix design to provide more

tolerance to lower bowl ratio characteristics. Modified mix designs shall be submitted to Tauranga District Council for acceptance.

• Increase the unbound pavement thicknesses to achieve the Bowl Rate characteristics required.

• Modify the pavement construction by stabilisation and/or reinforcement to achieve the Bowl Ratio characteristics

Where modification to the characteristics of the pavement construction are made by designers, compliance testing shall be provided to Tauranga District Council supporting the certification of adequacy. Designers are permitted to delay the asphalt surfacing of roadways constructed on Ash soils to allow subgrade soils to regain strength



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and stiffness before re-testing. Any delays beyond issue of a 224 Certificate will be permitted provided a suitable and agreed bond is lodged with Council. Such a bond will generally be 1.5 times the cost of reconstructing the road to meet the requirements of Section 9.D. 9.G.3 Other Surfaces Surfaces including bitumen and chip or unit block paving are to be proven for adequacy by proof rolling in accordance with 9.G.1. Testing is to be witnessed by the Tauranga District Council. Conclusions on adequacy for surfacing is subjective and acceptance or rejection is to be agreed between the Council and designer.

9.H Carriageway Surfacing

9.H.1 The finished carriage surface shall provide users with a smooth, even, and comfortable riding surface. Residential culdesacs and local roads, including service lanes may be surfaced with 25mm of compacted asphaltic concrete, a two stage seal coat or other approved surfacing. Principal, arterial and industrial roads will require specific design in accordance with Austroad “Guide to the Structural Design of Pavements” and current TNZ specifications. All culdesac heads (turning circles) shall be surfaced with asphaltic concrete.

9.H.2 Three forms of surfacing are acceptable. They are:

• Alternative 1: First and second coat chip seals (9.H.3) • Alternative 2: Hot laid asphaltic concrete (9.H.4) • Alternative 3: Interlocking concrete block paving (9.H.5)

9.H.3 Alternative 1: First and second coat chip seals (a) First coat sealing with asphaltic cutback shall be to TNZ specification P/3 and M/1. Sealing chips used are to comply with the TNZ specification M/6 provided that, where necessary to avoid the high transportation costs of imported hard chip, local stone may be used where the loss by the LA abrasion test does not

C10 A two coat seal is two separate seal coats generally carried out 12 months apart (Alternative 1). A twin coat (Bi-Couche) is a single coat seal with a wet lock, generally grade 3 with grade 5 carried out on the same day. The residual bitumen is considerably less than a two coat



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exceed 40%.

seal. Using this as a combination with a second coat could be an attractive alternative to Asphaltic Concrete because property sales occur generally within the first 12 months of s.224 issue.

(b) To avoid the discomfort to pedestrians from rough surfaces and the unnecessary costs of later seal coats through void filling, the size of the chip used for first and second coats should be no larger than that necessary to maintain a non-fatty and reasonably skid-resistant surface until the next seal coat is applied (c) For first coat chip size should be generally grade 4 although grade 3 may be necessary on primary streets. Where asphaltic concrete is used for the finished surface a grade 5 chip is recommended. For second coat seals the chip size will vary between grade 4 and grade 2 according to the function of the street, the traffic volume and the wear resistance of the stone (abrasion test). On local residential streets where traffic is light and pedestrian comfort is of considerable importance, grade 4 chip may be used whereas on collector and primary streets larger sizes my be preferred.

(d) Sizes of chips or cover aggregate for the two coats should be compatible.

(e) The second coat seal is to comply with standard specification P/4 and two options are generally available to the consent holder by negotiation with the Group Manager of City Services. The options are

• The developer may complete the second coat seal. In general this should be 12 months after the application of the first coat seal.

• There is an economic advantage in obtaining as much usage as possible from the first coat seal within the limits of maintaining a sound surface condition, and then applying the second seal when timely. To this end the consent holder = shall pay to Council the cost of the second coat seal and this will be programmed into Council’s Reseal programme. The cost will include for maintenance of the first coat seal.

9.H.4 Alternative 2: Hot laid asphaltic concrete Where asphalt is to be applied, such streets, cul-de-sacs, service



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lanes and rights-of-way shall be surfaced with a minimum compacted thickness of 25mm of asphaltic concrete complying with TNZ specification M/10. The method of laying is specified in TNZ P/9. Principal, arterial and industrial streets will require an additional thickness of asphaltic concrete determined by specific design. Imprinted asphaltic concrete shall have a minimum compacted thickness of 25mm measured from the bottom of the imprint. As asphaltic concrete is not in itself completely waterproof a first coat seal or similar is required to provide an initial waterproofing layer, using an appropriate asphaltic binder. A minimum of 1.0 litre per square metre of residual penetration grade bitumen is required. The manufacturers recommended time is to elapse between first coat and laying of asphaltic concrete to ensure curing of binder. 9.H.5 Alternative 3: Interlocking concrete block paving The consent holder may, if they wish, surface the road carriageway with interlocking paving blocks designed and laid generally in accordance with Drawing R15, and NZS 3116:2002 for Concrete Segmental Paving. Manufacture, testing, acceptance and supplies of concrete segmental pavers shall comply with AS/NZS 4455 and AS/NZS 4456. Paving units must have in built separators. A 12 month maintenance period may be required at 224 for paved areas to ensure “lock up is attained”. This may include periodic additional sanding/filling of joints and attention to excessive settlement or movement. The finished paving shall be “Pave locked”. When using paving stones particular attention should be given to subterranean drainage, and retaining a dry subgrade. 9.H.5.1 Alternative paving block materials require a detailed submission and the approval of the Group Manager of City Services.



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9.I Service Lanes

9.I.1 Commercial Service Lanes Where commercial development is to be provided with access by means of a service lane it should consist of a minimum carriageway width of 5.5m with kerb and channel both sides. Consideration may be given in special circumstances (dictated by topography) to providing kerb and channel on one side only. Kerb and channel may be mountable with provision for sumps for stormwater removal. A minimum compacted depth of 150mm and a two coat seal or similar approved surface. (Refer Drawing R16) For swept path design criteria refer to “New Zealand on Road Tracking Curves” published by LTSA October 1995.

9.I.2 Industrial Service Lanes (a) Industrial service lanes shall be constructed with a minimum subgrade strength of CBR 7. Where the service lane serves properties on one side only, the carriageway surface may have a single cross fall with kerb and channel on the lower side and a concrete edging strip flush with the surface on the high side, otherwise shall be constructed with kerb and channel both sides (Refer to Drawing R16). (b) Specific requirements may also call for the provision of passing bays and/or turning circles. (c) Maximum grades shall not exceed 12.5% and a minimum grade shall not be less than 0.5% (d) For swept path design refer to “New Zealand on Road Tracking Curves” published by LTSA October 1995.



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9.J Parking Bays/Pedestrian Accessways

9.J.1 Parking bays shall be constructed to the same standard as the adjacent road pavement. It is recommended that the surface of the parking bay be treated differently from that of the street to differentiate its use. A dish channel constructed to Drawing R7 shall be used where the parking bay falls to the carriageway.

9.J.2 Pedestrian accessways shall be as short as possible, with a clear line of sight through their length, and be generally constructed in accordance with Drawing R16. Provision shall be made for disposal of stormwater flowing down the length of the accessway and across the road footpath.

Pedestrian accessways should not be steeper than 1 in 6. Where the ruling gradient is steeper, steps and combinations of steps and graded path may be necessary. Where paths are constructed steeper than 1 in 8 a permanent non-skid surface and a handrail should be provided. Where a significant amount of surface water will be concentrated by the footpath in a pedestrian accessway, it shall be collected by a dished channel and disposed of through a 450 mm x 450 mm sump(s) or approved alternative with a maximum run of 60m.

Pedestrian ways shall have access constraints (staples) at each entry constructed of 50 mm diameter galvanised pipe, at least 900 mm above ground level. These are to prevent the uncontrolled access of cycles / motorcycles.

9.J.3 The accessway detail on Drawing R16 represents a minimum standard. Alternative specific designs for both the path and fencing are encouraged to enhance the subdivision.

9.K Private Ways

9.K.1 Private ways shall generally be formed in accordance with Drawing R17 (Residential) or R18 (Rural).

9.K.2 Where necessary, stormwater drainage shall be provided so that the maximum “run of water” does not exceed 90m.



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9.K.3 A standard vehicle crossing shall be provided for each residential private way in accordance with the plan dimensions of Drawings R12 and R13.

9.K.4 Where, as a requirement of the Resource Consent, street lighting is to be provided in the private way, it shall be to the same standards as would be required for the road network.

9.K.5 Private ways (rights of way) serving up to 12 dwellings shall have a properly formed and sealed carriageway as per the table below and Drawing R1. The minimum compacted depth of aggregate shall be 150mm and a two coat seal or other approved surface. Kerbs may be mountable but provision must be made to control and dispose of stormwater. This may require non-mountable kerbs to control overland flow paths between adjacent lots.

No of Dwellings Seal Width ROW Width

(Total) between buildings 1 or 2 2.4m 2.7m 3 to 4 2.5m 3.0m 5 to 12 5.0m 6.0m

9.K.6 For private ways serving up to two dwellings vehicular access may be provided by concrete strips. Two concrete strips 750mm wide by 100mm thick with a 750mm space between is acceptable. Concrete strips shall have a minimum compressive strength of 17.5 Map after 28 days. Where the subgrade conditions are poor, the Group Manager of City Services may require concrete strips to be reinforced with 665 mesh.

9.K.7 Private ways in excess of 70m shall have a passing bay constructed at approximately their mid point. Private ways longer than 100m in length shall require specific design and approval

9.K.8 The maximum gradient of any private way shall be 20%.

9.K.9 The maximum number of dwellings off any private way both in the urban and rural area shall not exceed 12.

9.K.10 Private ways must be sealed:



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• Where the presence of an unsealed right of way may have an adverse effect on an adjoining property

• Where the proposal may not be considered to provide an all weather vehicular access.

• Where the traffic density expected on rights of way warrant a higher standard of formation.

9.L Cuttings and Embankments

9.L.1 Urban road batters for cutting and embankments shall normally be constructed outside the street boundary and any batters encroaching the street boundary may or may not be allowed at the discretion of the Group Manager of City Services, provided that where such dispensation is permitted, the face of the batter shall be protected as directed by the Group Manager of City Services. Where possible, batters should not be steeper than 20% (1:5) with a provision for forming a vehicular entrance into each lot at a gradient not steeper than 20% from the back of the footpath. (See also Section 9.C.7) 9.L.2 Where, in the opinion of the Group Manager of City Services, the stability of any embankment as planned is in doubt, then the Group Manager of City Services may require a stability analysis of the slope under saturated conditions to be carried out. 9.M Auxiliary Turn Treatments / Seal Widening 9.M.1 Auxiliary turn lanes and seal widening improve road capacity and road safety. These shall be installed at all intersections and entranceways where the warrant is met in accordance with Section: 5.9 of part 5. Austroads: Intersections at Grade.

C11 Applicable where new or existing roadways require earthworks which affect adjacent properties

9. ROAD CONSTRUCTION

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