maintenance of unsealed roads 2009

Gravel Road Maintenance Issues & Sustainable Solutions

Jointly prepared by

David Edge - Roading Manager, Hurunui District CouncilKen Avant - Road Projects Engineer, Waimakariri District Council

Carl Grabowski - Senior Transportation Engineer, MWH

Introduction• Management & Budgetary Constraints • Ratepayer, Road-user & Council Expectations• Levels of Service• Alternatives to Long-term Maintenance• Reliable “good old” Methods & Innovative Alternatives• Optional Sustainable Options• Questions



Management & Budgetary Constraints

• Sealing Roads = favoured option for Road Users & Councils(comfort, lower maintenance, etc).

• Although maintenance costs can be relatively high, LV Roadsdo not easily qualify for Seal Extension funding.

• Councils / Contractors constantly searching for methods to reduce maintenance needs.

• ‘Crab Bucket Syndrome’ & sharing of cross-boundary efficiencies.

• Sustainable roading research & workshops.


Ratepayer, Road-user & Council ExpectationsRatepayer Road-user Council

Relatively smooth - no corrugations / potholes, minimum ‘flying’ gravel.

Minimum corrugations & potholes - road user comfort, safety & traction.

Meet contractual specification, prompt & effective response.

Minimum dust nuisance (inhalation & household effects).

Minimum dust nuisance (visibility & vehicle effects).

Well bound running course, cost-effective dust suppressants, low environmental impacts.

Use of the shoulder / verge (landscaping, parking, etc).

Verge scrub-free / well maintained to improve visibility, emergency / rest stopping.

Contractual compliance (environmental mtce, shape, drainage, max road width maintained.

Stormwater mgmt within road corridor.

No ponding, rutting, rilling, potholing, aquaplaning.

Contractual drainage compliance - safety, asset maintenance & environmental.


Typical examples of rural heavies causing major damage to our unsealed roads:


Levels of Service


• Clear wording in documents

• ‘Total Management Systems’

• Good grader regimes

• Maintenance Contractors buy-in & investment

• Partnering agreements to share benefits / losses

• “Kaizen” Continuous improvement - not just BAU

Contract Issues


Alternatives to Long-term Maintenance


Foamed Bitumen stabilization of an unsealed road Kennedys Hill Road, Waimakariri District

• Steep, windy section• Layer thickness / fines• Drainage issues• Further maintenance• Ongoing monitoring


• Good finish• Cracking• Drainage• Surplus material• Some potholes• Maintenance


Otta Seals - Local & International Practice

• Single chip seal with prime & binder (13.2mm)thickness = ALD (8 - 10mm)

• Single Otta seal with binder & graded aggregate (no prime)thickness = minimum 16mm

• Double Otta seal with binder & graded aggregate (no prime)thickness = minimum 32mm


Type Additional Application Expected life (Years)Single Otta seal No sand cover Temp. seals &

maint. reseals5 - 6 (dependant on

surfacing type & quality)

Single Otta seal with sand cover

Fine sand in the sand cover

AADT ≤ 500 9 - 11

Crusher dust or river sand in the sand cover

10 - 12

Double Otta seal AADT > 500 12 - 15

Detailed info available in comprehensive guideline produced by the Norwegian Public Roads Administration (1999)

“A Guide to the Use of Otta Seals”


Mayes Rd, HDC (Nov. 2004)• AADT ≤ 500• Unsuitable materials• Good finish & drainage• ‘Life Cycle’ cost benefits• No maintenance

• Keddell Road, Central Otago DC• Mayes Road, Hurunui DC• Church Road, Dunedin CC• Sinclair Road, Southland DC• Peroa Road, Gisborne DC

Fulton Hogan have done several trials


Otta Seal - Proposed Bramleys Road application (WDC)

Issues• Dust nuisance• Rutting & potholes• Drainage

Choice Influences• Regular complaints• Good structure / shape• Low volume (117/day)• Drainage - minor work


Otta Seal - International Practice

International• Norway / Sweden / Iceland • Kenya / Botswana / Zimbabwe / SA• Bangladesh / Australia



Single Otta seal with sand cover seal in Botswana“beds down” after a few months in service (a) and (b),

and still looks good after 9 years in service (c).

(a)

(c)

(b)



Single Otta seal in Bangladeshaggregate spread by hand (a), compacted with loaded trucks (b), “beds down” and looks good after 2 years in service (c).

(a)

(b)

(c)



Otta seals in Kenya (a) and (b) and South Africa (c) and (d) using natural quartzitic and laterite aggregates.

(a)

(b)

(c)

(d)

Reliable “good old” Methods & Innovative Alternatives


Issues with reliable “good old” methods

• ‘Smoothing’ vs. Rip & Reshape• TTM during maintenance operations• Heavy vehicles & gravel loss• Raised shoulder syndrome



Innovative AlternativesOvergrown shoulder - reclaiming road width

• Consider landowner concerns - metal-wash, mowing, etc.• Tractor mounted shoulder trimming - soil / vegetation build-up on

shoulder trimmed back to regain metal width (Killiner Contracting, NZ)


Raised shoulder syndromeTractor or grader mounted shoulder reclaimer available to eliminate

soil / gravel build-up on shoulder - loosened and swept off or re-used.“All American Disk” - Doyle Inc, Minnesota, USA“Tiger Claw” - Agriquip Ltd, New Plymouth, NZ

Killiner Contracting, NZ


Shoulder reclaiming available locally (Killiner Contracting, NZ)• Trialed in various N-Island districts• Potential for minimum 20km/day (both sides) @ approx. $0.05/m• Reclaims between 50 - 100m3 material (mostly metal) / side / km• TLA’s in USA - annual cycle in maintenance contracts


Pneumatic (tyred) roller mounted on rear of grader (locally available - Walk ‘n’ Roll International Ltd, Auckland) and various blade attachment options (used by Sicon / SDC) can make rural road maintenance a little easier.


Towed machinery used in USA to pulverize gravel and sod windrows into re-usable material on unsealed roads.


Optional Sustainable Solutions

Cost / benefit comparison of options being investigated as alternatives to Grader maintenance

• Reclaimed metal + Ballast + Cement stabilisation

• Reclaimed metal + Otta seal

• Re-metalling + Otta seal

• Stabilisation (Cement / FB) + Seal (Otta / Chip)

• AWT (Full reconstruction + Chip seal)


Useful References / Acknowledgements• “A Guide to the Use of Otta Seals” - Norwegian Public Roads Administration• “Tractor-Mounted Shoulder Reclaimer - Works Well and Saves Money” -

US Roads, Road Management Journal• “A Ditch in Time” - Rural Home Technologies, Road/Driveway Maintenance• “Gravel Roads: Maintenance & Design Manual - Section V: Innovations” -

US Environmental Protection Agency• “Unsealed Roads are Sustainable” - 1997 IPENZ Conference (Alan Ferry) • “Replacing Waste Oil as a Dust Minimisation Technique” - Jeff Waters (FH)

2007 LV Roads W/shop Presentation• “The All American Disk” - Doyle Inc. (video clip on Google / YouTube)• “Tiger Claw” marketing material supplied by Richard Capper, Agriquip


Questions?

Thank You

maintenance of unsealed roads 2009

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