Doc #60 — Road and Bridge Maintenance

---

RECOMMENDED ACTIONS (BY URGENCY)

First months:

1. Establish a route classification system (Tier 1–4) based on food, energy, and population connectivity — not pre-war traffic volumes
2. Redirect road maintenance crews from cosmetic work to drainage clearance on Tier 1 and Tier 2 routes
3. Inventory bridge condition data from Waka Kotahi’s Bridge Management System (BMIS) and council records — identify the most vulnerable structures
4. Stockpile bitumen at regional depots for emergency patching of Tier 1 routes only

First year:

5. Begin planned gravel reversion on Tier 3 routes: strip remaining seal where it is breaking up, regrade surface, restore drainage
6. Conduct structural assessment of all bridges on Tier 1 and Tier 2 routes, prioritized by age and material
7. Establish regional bridge repair teams with timber construction capability
8. Commission weight restrictions on bridges identified as vulnerable

Years 2–5:

9. Transition all Tier 3 and Tier 4 roads to unsealed management or abandonment
10. Begin timber bridge construction program for replacement of deteriorating structures on critical routes
11. Develop concrete patching capability for Tier 1 roads using NZ-produced cement (Doc #97)
12. Establish training pipeline for road and bridge maintenance trades (Doc #156)

---

ECONOMIC JUSTIFICATION

Road maintenance is foundational infrastructure that every other recovery activity depends on. Food moves by road. Fuel moves by road. Medical supplies, census teams, maintenance crews, and trade goods all move by road. Allowing the road network to degrade beyond usability would impose costs across every sector of the recovery.

Labor force composition for the maintenance program:

A functioning road and bridge maintenance program under recovery conditions requires workers across four occupational categories:

• Civil and structural engineers: 200–400 person-years annually for route assessment, bridge structural evaluation, drainage design, and construction oversight. These are the scarcest skills and the hardest to replace through training. Triage: prioritize the highest-qualified engineers on Tier 1 bridges and new bridge construction design; generalist technicians and qualified tradespeople can manage routine road maintenance without engineering supervision.
• Road workers and equipment operators: 2,000–3,500 person-years annually for grading, drainage clearance, culvert work, re-metalling, slip clearance, and road marking. This is the largest occupational group. The skills are learnable within weeks for basic operations; experienced operators are more productive but not irreplaceable.
• Heavy equipment operators: 400–700 person-years annually for grader, excavator, and roller operation. Distinct from general road workers due to the skill and fuel commitment attached to each machine. Equipment attrition concentrates these workers on a shrinking number of serviceable machines over time.
• Materials suppliers and logistics: 300–600 person-years annually for quarry operation, aggregate haulage, timber procurement and treatment, and materials depot management. This function is partly absorbed into the general transport and quarrying workforce but deserves explicit accounting — without consistent materials supply, maintenance crews cannot function regardless of skill.

Total estimated program: 3,000–5,000 person-years annually for the maintained network (Tier 1 and Tier 2, approximately 18,000–30,000 km). This is fewer total workers than the pre-war road maintenance and construction workforce (~5,000–7,000), but represents a higher share of the available labor force given overall workforce contraction.²

Proactive maintenance vs. managed deterioration — a direct comparison:

Approach	5-year outcome	15-year outcome	Labor cost
Proactive Tier 1/2 maintenance	Network functional, bridges inspected and maintained	Core network still functional; some bridges replaced with timber	3,000–5,000 person-years/year
Deferred maintenance, reactive only	Sealed surfaces breaking up; some bridges restricted or closed	Network fragmented; major route disruptions; replacement prohibitively costly	Lower initially, sharply higher later
Network abandonment	Rapid degradation; bridge failures begin within 3–5 years	Network mostly unusable for heavy vehicles; all recovery logistics impaired	Near zero — but the cost is borne by every other sector

The deterioration scenario is not cost-free — it transfers costs onto every downstream user. A failed bridge on a food corridor does not eliminate the cost of food transport; it multiplies it through detours, smaller vehicle loads, road damage, and eventual route abandonment. A road that deteriorates to the point of impassability for heavy vehicles eliminates supply chain connectivity entirely, imposing costs that no downstream investment can recover.

Breakeven case: The road network serves as the connective tissue for all other recovery investments. A functioning cement plant (Doc #97), a productive dairy farm (Doc #76), a working steel mill (Doc #89), or a functioning hospital — none of these produce recovery value if their outputs cannot move. Road maintenance is therefore a prerequisite, not a competing priority. The breakeven question is not whether to maintain the network but how much network to maintain: concentrating resources on Tier 1 and Tier 2 routes produces a far better return per person-year than attempting to maintain the full 94,000 km system.

Opportunity cost: The 3,000–5,000 workers assigned to road maintenance cannot simultaneously work in food production, construction, or manufacturing. This is a real tradeoff. The assessment is that the logistics multiplier — roads enabling every other recovery sector to function — justifies the labor commitment. A recovery economy that saves labor by abandoning road maintenance will lose far more output in impaired food distribution, fuel delivery, and inter-regional trade than it gains from reallocating those maintenance workers.

Community-based labor mobilization: In predominantly Māori rural communities — Northland, East Coast, Bay of Plenty, Southland — the traditional practice of mahi tahi (communal labor) provides an existing organizational model for community-based road drainage maintenance, reducing demand on centrally-deployed maintenance crews.³ Mahi tahi involves community members contributing labor to projects that benefit the whole group, organized through hapū leadership — analogous to the corvée labor system that built much of pre-modern European infrastructure. Under recovery conditions, mahi tahi traditions have direct relevance to the labor mobilization challenge:

• Community-based drainage maintenance: Marae-based communities in rural areas can maintain local road drainage (culvert clearing, side drain clearing) using the mahi tahi model. This is particularly relevant for Tier 3 roads in areas with significant Māori rural populations.
• Communal bridge inspection and repair: Minor timber bridge repairs and deck replacements are within the capability of a skilled community work party. Organized through local hapū leadership and supported with materials (timber, bolts, tools), community-based repair programs can maintain low-volume rural bridge infrastructure without drawing on the specialized maintenance workforce.
• Workforce integration: Recovery-era road maintenance crews working in predominantly Māori rural communities should understand mahi tahi as an organizational model and engage with hapū leadership to mobilize community participation in maintenance tasks, rather than treating road maintenance as an entirely externally-delivered service.

For practical guidance on engaging with iwi and hapū on labor mobilization, see Doc #150.

---

1. THE NZ ROAD NETWORK

1.1 Network composition

NZ’s road network breaks down approximately as follows:⁴

Category	Length (km)	Current surface
State highways	~11,000	Predominantly sealed
Urban local roads	~17,000	Predominantly sealed
Rural local roads	~66,000	Mixed; approximately 25–35% already unsealed
Total	~94,000	~65,000 sealed, ~29,000 unsealed

Approximately 29,000 km of NZ road is already unsealed — mostly low-volume rural roads.⁵ These roads are currently maintained by councils using graders, and they function adequately at speeds of 50–80 km/h. The transition from sealed to unsealed is an expansion of existing practice.

1.2 Current condition

Road condition varies enormously. State highways are generally well-maintained, though deferred maintenance has been a persistent concern — Waka Kotahi has identified a significant backlog in renewal work.⁶ Local roads are maintained to varying standards depending on council budgets. Some rural sealed roads are already in poor condition, with cracking, potholes, and failed drainage.

Under recovery conditions, this pre-existing condition variation matters. Roads already in poor condition degrade faster. The route prioritization framework should account for current condition as well as strategic importance.

---

2. ROUTE PRIORITIZATION

Not all roads are worth maintaining. The pre-war road network was built for an economy that no longer exists — commuter traffic, tourism, commercial freight patterns that will change fundamentally. Route prioritization must reflect post-event realities: food production corridors, energy infrastructure access, population centers, and inter-regional connectivity.

2.1 Tier 1: Maintain indefinitely

Core national corridors connecting major population centers and food production regions. These routes justify the highest maintenance investment, including concrete patching and eventual resurfacing where feasible.

• Auckland–Hamilton–Tauranga (SH1/SH2/SH29): connects NZ’s largest city to the Waikato food basin and Bay of Plenty port
• Hamilton–New Plymouth (SH3): Taranaki energy and dairy corridor
• Wellington–Palmerston North (SH2/SH1): capital to Manawatū food production
• Christchurch–Timaru–Dunedin (SH1): Canterbury Plains food production, South Island inter-city
• Christchurch–West Coast (SH73): access to West Coast resources
• Key routes to major hydro stations (e.g., SH8 to Waitaki scheme, routes to Manapōuri)

Estimated Tier 1 length: 3,000–5,000 km.

2.2 Tier 2: Maintain while resources allow

Regional connectors linking secondary towns, key rural communities, and productive land to the Tier 1 network. Maintained as sealed or well-graded gravel.

• Routes to major food production areas not on Tier 1 (e.g., Hawke’s Bay, Southland, Northland)
• Hospital and emergency service access routes
• Port access roads (essential for coastal and eventual overseas trade)
• Rail-to-road intermodal connections

Estimated Tier 2 length: 15,000–25,000 km.

2.3 Tier 3: Reduced maintenance — gravel reversion

Low-traffic rural roads where communities exist but traffic volumes do not justify sealed surface maintenance. These roads revert to gravel with basic drainage maintenance.

• Secondary rural roads serving farms and small communities
• Forestry access roads (still needed for timber and firewood supply)

Management: grade 2–4 times per year, maintain drainage, patch washouts.

Estimated Tier 3 length: 30,000–40,000 km.

2.4 Tier 4: Abandon

Roads serving no essential recovery function. Maintenance ceases; the road reverts to a track or is reclaimed by vegetation.

• Tourist roads to destinations with no recovery value
• Redundant parallel routes where a single route suffices
• Remote roads serving no permanent population

Tier 4 designations that sever the only road access to Māori communities, Māori freehold land, or marae carry Treaty obligations — engagement with relevant hapū and iwi is required before any such designation (Doc #150).⁷

Estimated Tier 4 length: 15,000–25,000 km.

2.5 Traditional route knowledge

Aotearoa was a fully networked society before European arrival. Māori maintained an extensive network of overland trails (ara) and waterway routes throughout the country before and during the colonial period.⁸ These routes were not informal tracks — they were engineered paths, maintained by the communities that depended on them, connecting resource areas, settlements, pā, and gardening grounds. Many were maintained through communal labor organized at the hapū level.

Several aspects of the traditional ara network have direct recovery relevance for route prioritization:

• Route selection: Ara routes generally followed terrain with low flooding risk, accessible gradients, and reliable fords or crossing points. This route knowledge reflects centuries of trial and error in NZ-specific terrain, including the braided rivers and swampy lowlands that remain among the most challenging road-maintenance environments in NZ today. Pre-existing ara alignments sometimes offer superior routing to later-built roads in terms of drainage and flood resilience.
• Seasonal route knowledge: Iwi and hapū knowledge of seasonal route availability — which crossings are passable in winter, which sections are prone to flooding or slipping — is operational intelligence for recovery-era route prioritization. This knowledge is not uniformly documented and may exist only with local kaumātua.
• Natural crossing points: Traditional river crossings (awa) represent locations where generations of observation identified the most stable, shallowest, or most navigable crossing points on each waterway. In braided river systems (Canterbury, Hawke’s Bay, Southland), where bridges are widely spaced and crossing selection is technically complex, this knowledge has direct engineering value.

When conducting bridge and route prioritization surveys on Tier 1 and Tier 2 routes, include engagement with local iwi to access ara network knowledge and traditional crossing-point information. This is particularly valuable in areas where bridges are aging or at risk of scour failure and alternative crossings may be needed.

---

3. SURFACE MAINTENANCE WITHOUT IMPORTS

3.1 Bitumen: the binding constraint

Bitumen is a petroleum refinery product. NZ’s sole oil refinery at Marsden Point ceased refining operations in 2022 and operates as an import terminal.⁹ Even when it was refining, NZ imported most of its bitumen. There is no domestic substitute for bitumen in conventional road sealing.

Existing bitumen stocks: NZ maintains some bitumen stocks at refineries and regional depots for road maintenance. These stocks are finite and should be reserved exclusively for emergency patching on Tier 1 routes — not wasted on routine resealing that will eventually become impossible regardless.

Degradation timeline: A sealed road surface in NZ’s climate degrades significantly within 10–15 years without reseal. Cracking allows water infiltration, which causes subgrade failure, potholes, and eventual surface breakup.¹⁰ South Island roads in freeze-thaw zones degrade faster. North Island roads in high-rainfall areas are vulnerable to drainage failure.

Implication: The sealed road network is a wasting asset. Planning should assume that most sealed roads revert to gravel within 15–20 years. Tier 1 routes may be maintained as sealed for longer using rationed bitumen stocks and concrete patches, but even these will eventually transition.

3.2 Concrete

NZ can produce Portland cement from domestic limestone and clay deposits (Doc #97), though production requires a functioning kiln (temperatures of 1,400–1,500°C), grinding equipment, and a reliable fuel source (coal or wood). Concrete road surfaces or concrete patching of critical sealed roads is the only domestically sustainable sealed-surface option.

Limitations: Concrete roads require significant cement quantities, are labor-intensive to lay, and are less forgiving of subgrade movement than flexible bitumen surfaces. Concrete patching of potholes and failed sections on Tier 1 routes is more practical than full concrete resurfacing.

Best application: Concrete is most justified for bridge decks, intersection areas subject to heavy braking loads, steep gradients where gravel washes out, and short sections of Tier 1 routes where gravel is impractical (e.g., through urban areas).

3.3 Gravel

NZ has abundant aggregate resources — greywacke, basalt, and river gravel are available throughout the country.¹¹ Gravel roads are maintainable indefinitely with locally available materials and equipment.

Maintenance requirements: Gravel roads need periodic grading (reshaping the surface and restoring the crown to shed water) and periodic re-metalling (adding fresh aggregate to replace material lost to traffic and weather). A grader can maintain approximately 10–15 km of gravel road per day.¹² Annual re-metalling uses approximately 100–200 m³ of aggregate per kilometer, depending on traffic levels and climate.¹³

Performance: A well-maintained gravel road supports all vehicle types at speeds of 50–80 km/h. In wet conditions, speed should be reduced. Dust is a nuisance in dry conditions but not a safety issue. The performance gap relative to sealed roads is real — rougher ride, higher vehicle wear, slower speeds, dust — but entirely manageable.

Land tenure for aggregate extraction: Many NZ riverbeds and hillside quarry sites are on or adjacent to Māori land, and riverbeds frequently have customary interests attached. Gravel extraction without iwi engagement will generate conflict that obstructs the maintenance programme. Aggregate sourcing plans should pre-identify land tenure issues and establish agreements with tangata whenua before extraction begins (Doc #150).¹⁴

3.4 Drainage: the critical task

Poor drainage destroys roads faster than traffic, and this is true for both sealed and unsealed surfaces. Water that penetrates the road subgrade or pools at the road edge causes subgrade softening, rutting, slips, washouts, and pothole formation. In NZ’s high-rainfall climate, drainage maintenance is the single most important road maintenance activity.¹⁵

Key drainage tasks:

• Culvert clearing: Blocked culverts cause road washouts. All culverts on Tier 1–3 routes should be cleared at least twice yearly and after major storm events
• Side drain maintenance: Keeping roadside drains clear and properly graded so water flows away from the road
• Water table management: In areas with high water tables, maintaining functioning subsoil drains
• Slip clearance: NZ’s steep terrain produces slips that block roads and destroy drainage. Slip clearance on Tier 1 routes must be a priority response

As engineering survey capacity is stretched, traditional terrain knowledge held by kaumātua provides supplementary intelligence on slope instability and river channel behavior for road maintenance planning. Mātauranga Māori includes extensive knowledge of terrain behavior: which hillsides are prone to slipping after heavy rain, which river channels shift during floods, where clay soils cause road failure, and how to read landscape features as indicators of instability.¹⁶ This knowledge is the product of continuous observation of NZ landscapes under conditions that mirror recovery-era road risks — without modern drainage engineering, these relationships were survival knowledge. Kaumātua and local tohunga with environmental knowledge should be included in:

• Regional road condition assessments (identifying sections at highest slip and washout risk)
• Bridge scour vulnerability assessments (identifying river reaches with unstable channels)
• Route abandonment decisions (where traditional knowledge confirms that a particular alignment was never viable in high-rainfall years)

---

4. BRIDGE MAINTENANCE AND REPLACEMENT

4.1 NZ’s bridge stock

NZ has approximately 18,000 road bridges, ranging from small rural culvert bridges to major multi-span structures.¹⁷ The bridge stock includes:

• Steel bridges: Common for medium and long spans. Durable with maintenance (painting, bolt inspection, bearing maintenance). Corrosion is the primary enemy, especially in coastal and high-humidity environments.
• Concrete bridges: Predominant for modern construction. Long-lived (50–100+ years) if reinforcing steel does not corrode. Cracking that exposes reinforcing to moisture accelerates deterioration.
• Timber bridges: Still present in rural areas, though many have been replaced. Historically NZ’s standard bridge material.

4.2 Maintenance priorities

Bridges are the most irreplaceable components of the road network. A failed bridge can sever a route entirely, with detours of tens or hundreds of kilometers. Bridge maintenance should be prioritized above road surface maintenance.

Immediate priorities:

• Inspect all Tier 1 and Tier 2 bridges for structural condition, focusing on: bearing condition, deck cracking, corrosion of steel elements, scour at foundations, and timber decay
• Impose weight restrictions on bridges identified as marginal
• Stockpile maintenance materials: paint and corrosion inhibitors for steel bridges, timber for deck repairs

Ongoing maintenance:

• Steel bridges: repaint every 10–15 years to prevent corrosion.¹⁸ NZ can produce basic protective coatings — linseed oil-based paints (requiring flax seed crops and oil pressing capacity) or coal tar coatings (a byproduct if gasification processes are operational per Doc #56). These coatings are significantly less durable than modern epoxy or polyurethane bridge paints: linseed oil coatings may need reapplication every 3–5 years compared to 10–15 years for industrial coatings, and provide weaker protection in salt-spray environments
• Concrete bridges: seal cracks to prevent water reaching reinforcing steel. Monitor for spalling and reinforcing corrosion
• Timber bridges: inspect for rot and insect damage. Replace individual members as needed — this is the advantage of timber: bridges can be repaired component by component

4.3 Timber bridge construction

NZ has strong historical precedent for timber bridge construction. Before the mid-20th century, most NZ bridges were timber.¹⁹ The materials and skills exist for a return to timber bridge building.

Suitable timbers: Radiata pine (treated) is the most available NZ plantation timber. Macrocarpa (Cupressus macrocarpa) has good natural durability and is widely planted. Native timbers — totara, matai, puriri — are highly durable but limited in supply and subject to conservation constraints. For bridge construction, treated radiata pine is the practical default, with macrocarpa for elements requiring natural durability (e.g., piles in contact with water).²⁰

Design considerations:

• Span: Timber beam bridges are practical for spans up to approximately 12–15 m with single beams, and longer with truss designs. For longer spans, multiple-span designs using intermediate piers are more practical than attempting long single spans
• Load capacity: Bridges on Tier 1 and Tier 2 routes must carry heavy vehicles (up to 44 tonnes gross). This requires substantial beam sections — typically 300 mm x 500 mm or larger laminated beams for the main girders, depending on span
• Deck: Timber plank deck on transverse beams. Wearing surface of additional sacrificial planking or gravel-over-timber
• Foundations: Timber piles driven into the riverbed, or concrete piers if cement is available (Doc #97). Scour protection at piers is critical in NZ’s flood-prone rivers
• Treatment: Boron or copper-chrome-arsenate (CCA) treatment extends timber life from an estimated 10–15 years untreated to 30–50+ years in ground contact.²¹ CCA treatment requires copper sulfate, sodium dichromate (chromium source), and arsenic pentoxide — none of which NZ produces domestically in the required forms. Existing CCA stocks at NZ’s approximately 20 timber treatment plants are finite and should be reserved for structural applications such as bridge piles and bearings. Boron treatment (using borax) is simpler but provides protection against insect attack and fungal decay only in non-leaching conditions (i.e., covered timber, not piles in water). NZ has existing timber treatment plant infrastructure but the chemical feedstock supply chain is the binding constraint

Land access for construction: Bridge footings, approach roads, and construction compounds on Māori land require access agreements with tangata whenua. Bridge construction programmes on Tier 1 routes should pre-identify land tenure issues before construction begins to prevent delays (Doc #150).²²

Construction workforce: Timber bridge construction requires carpentry and structural engineering skills, not specialized bridge engineering. A team of 6–10 workers with a crane or excavator for lifting heavy beams can construct a single-lane bridge of moderate span (10–15 m) in 2–4 weeks.²³

4.4 Vulnerable bridges

Certain bridge types and locations warrant particular attention:

• Long-span steel bridges: These cannot be replaced with timber. If a major steel bridge fails, the route may be permanently severed unless an alternative crossing can be found. Maintenance of long-span steel bridges on Tier 1 routes is a critical priority
• Coastal bridges: Salt spray accelerates corrosion of steel and reinforced concrete. Coastal bridges on critical routes need more frequent inspection and maintenance
• Bridges over braided rivers (Canterbury): Scour and channel migration threaten foundations. Long bridges across the Waimakariri, Rakaia, and Rangitata rivers are critical and difficult to replace
• Aging bridges: Some NZ bridges are 80–100+ years old. These structures may be approaching end of life regardless of maintenance

---

5. EQUIPMENT AND FUEL

Road maintenance is equipment-intensive. The core equipment fleet includes:

• Graders: Essential for maintaining gravel roads. Fuel-dependent (diesel). NZ has graders distributed across council depots nationwide
• Rollers: For compacting gravel surfaces after grading or re-metalling. Some can be towed; powered rollers need fuel
• Excavators: For drainage work, slip clearance, culvert installation, and bridge construction. Fuel-dependent
• Trucks: For transporting aggregate, timber, and equipment. Fuel-dependent initially; wood gas conversion possible (Doc #56)

Fuel constraint: All this equipment runs on diesel. Under fuel rationing (Doc #53), road maintenance must compete with agriculture, emergency services, and other essential uses for limited fuel. Prioritizing Tier 1 and Tier 2 routes concentrates fuel use where it has the highest return.

Electrification potential: Some equipment — particularly rollers and small site vehicles — could be converted to electric operation using NZ’s grid power. Excavators and graders are harder to electrify due to high power demands (150–300 kW for a typical road grader) and remote operating locations far from charging infrastructure. Current battery-electric construction equipment offers 4–8 hours of operation per charge compared to effectively unlimited range with diesel refuelling, making them impractical for dispersed rural maintenance work. Battery-electric or overhead-wire solutions are longer-term possibilities (Phase 4+).

Equipment attrition: Machinery wears out. Hydraulic seals, cutting edges, tires (Doc #33), engine parts — all require replacement. NZ’s machine shops (Doc #91) can fabricate some components, but complex items (hydraulic pumps, electronic controls) are difficult to reproduce. The equipment fleet degrades over time, and maintenance becomes increasingly labor-intensive as mechanical aids are lost. This is the strongest argument for concentrating maintenance on a reduced network: fewer kilometers maintained means slower equipment attrition.

---

6. CRITICAL UNCERTAINTIES

Uncertainty	Why it matters	How to resolve
Actual bridge condition data	Some bridges may be closer to failure than records indicate	Physical inspection program (Year 1)
Bitumen stock volumes	Determines how long Tier 1 routes can remain sealed	Inventory at refineries and regional depots
Timber treatment chemical stocks	Untreated timber bridges last 10–15 years; treated bridges 30–50+	Inventory CCA and boron stocks
Equipment parts availability	Graders and excavators are essential; failure rate is unknown	Machine shop capability assessment (Doc #91)
Fuel allocation for road maintenance	Competes with agriculture, emergency services	Depends on national fuel allocation model (Doc #53)
Cement production timeline	Concrete patching depends on domestic cement supply	Doc #97 development schedule
Climate change effects on drainage	Changing rainfall patterns may increase drainage failure rates	Monitor and adapt

---

CROSS-REFERENCES

Transport and vehicles (direct dependencies):

• Doc #033: Tires — hard dependency. Tire scarcity (Doc #033) creates pressure to reduce vehicle speeds, which in turn reduces road surface wear and extends the usable life of gravel roads. Tire availability also constrains road maintenance vehicle operations. Road surface quality reciprocally affects tire wear rates.
• Doc #054: Vehicle Electrification — electric and hybrid vehicles impose different load profiles on road surfaces than heavy diesel vehicles. As the vehicle fleet transitions (partially), road design loads and maintenance priorities shift. Electric utility vehicles may reduce fuel constraints for light maintenance tasks.
• Doc #059: Bicycle Fleet — bike networks represent a low-infrastructure supplement to the road network for personal travel on short routes. A well-maintained gravel road is adequate for bicycle use; bicycle-priority corridors in peri-urban areas reduce the need to maintain sealed surfaces for all-purpose vehicle use.
• Doc #6: Vehicle Management — vehicle preservation extends road surface life (lighter loads, lower speeds); route rationalization in vehicle management planning should align with the Tier 1–4 road classification framework.
• Doc #61: Rail — complementary system. Rail (Doc #61) carries intercity freight on ~4,000 km of track. Road maintenance of intermodal transfer points (road-to-rail loading facilities) is a Tier 1 priority. Rail does not substitute for road in rural and last-mile contexts; the two systems must be planned together.

Materials (supply dependencies):

• Doc #089: NZ Steel (Glenbrook) — hard dependency for bridges. Steel fabrication for bridge bearings, bolts, reinforcing bar, and structural elements depends on domestic steel production. As steel imports cease, Glenbrook’s output capacity becomes a ceiling on how many steel-dependent bridge repairs can be made per year.
• Doc #097: Cement and Concrete — hard dependency for Tier 1 road and bridge surfaces. Domestic cement from Doc #097 is the only sustainable source of concrete for road patches and new bridge decks. Road maintenance planning on Tier 1 routes should be synchronized with Doc #097 production ramp-up schedule.
• Doc #102: Charcoal Production — relevant to timber treatment (coal tar substitutes for wood preservatives) and potential alternative fuel for road maintenance vehicles.

Governance (legal and authority dependencies):

• Doc #144: Emergency Powers — governance dependency. Route prioritization decisions that effectively abandon Tier 3 and Tier 4 roads require legal authority — affected communities lose access and may resist. Doc #144 provides the emergency powers framework under which route rationalization can be legally enacted and enforced. Any road closure decision on local or regional roads must be made through the appropriate emergency governance structure, not unilaterally by road maintenance agencies.
• Doc #149: Land Use — road corridors and bridge abutments occupy land under varying tenure. Route rationalization affects land use planning. Road abandonment may release land for alternative uses. New route construction or diversion requires land access authority. These decisions interact with land use governance described in Doc #149.
• Doc #150: Treaty of Waitangi and Māori Governance — Māori land (Māori freehold land, Treaty settlement land) may be affected by road maintenance or abandonment decisions. Engagement with relevant iwi and hapū is required before decisions about routes crossing or adjacent to Māori land are made, as described in Doc #150.

Workforce:

• Doc #91: Machine Shop Operations — fabrication of replacement parts for graders, excavators, rollers, and other maintenance equipment. As imported spare parts run out, machine shop capability becomes the constraint on equipment serviceability.
• Doc #53: Fuel Allocation — road maintenance equipment competes for limited diesel with agriculture, emergency services, and freight. The Tier 1–4 prioritization framework in this document is, in part, a framework for concentrating fuel use where it has the highest maintenance return.
• Doc #56: Wood Gasification — potential alternative fuel source for maintenance trucks and lighter vehicles, reducing the fuel allocation constraint.
• Doc #157: Trade Training — pipeline for training road workers, equipment operators, and bridge carpenters. Road maintenance trades need formal training pathways, particularly for timber bridge construction skills that are not currently common in the NZ workforce.

---

---

1. NZ road sealing history: extensive sealing of rural roads occurred primarily in the 1950s–1970s. Before this period, most roads outside major urban areas were unsealed. See Ministry of Transport, “The New Zealand Road System: History and Development.”↩︎

2. Employment estimates based on Statistics NZ industry data for road and bridge construction. The exact figure varies with construction cycles. https://www.stats.govt.nz/↩︎

3. Mahi tahi as an organizational principle in Māori community labor: the communal labor tradition has been documented in ethnographic literature (Best, 1924; Buck, The Coming of the Maori, 1949) and continues as an active organizational model in contemporary marae-based community projects. The term mahi tahi (literally: work together) is used in modern contexts including community environmental restoration, marae construction and maintenance, and community food production. Its application to infrastructure maintenance is a direct extension of existing practice.↩︎

4. Waka Kotahi NZ Transport Agency, “Annual Report,” various years. NZ road network statistics are published in the National Land Transport Programme and territorial authority records. The ~94,000 km total and ~11,000 km state highway figures are commonly cited in NZTA publications. https://www.nzta.govt.nz/↩︎

5. Waka Kotahi NZ Transport Agency, “Annual Report,” various years. NZ road network statistics are published in the National Land Transport Programme and territorial authority records. The ~94,000 km total and ~11,000 km state highway figures are commonly cited in NZTA publications. https://www.nzta.govt.nz/↩︎

6. Waka Kotahi has reported a growing deferred maintenance and renewal backlog in state highway assets. See Waka Kotahi, “National Land Transport Programme” and “State Highway Investment Proposal,” various years.↩︎

7. The extent of Māori land in NZ is documented in records held by Te Arawhiti (Office for Māori Crown Relations), Land Information New Zealand (LINZ), and Māori Land Court (Te Kooti Whenua Māori). Māori freehold land comprises approximately 1.4 million hectares, or roughly 5% of NZ’s land area, distributed unevenly across regions with concentrations in Northland, Bay of Plenty, East Cape, and parts of the South Island. Road corridors across this land are subject to legal access arrangements that do not automatically transfer authority to road maintenance agencies. See Doc #150 for Treaty obligations framework.↩︎

8. Traditional Māori trail networks and terrain knowledge are documented in ethnographic and historical sources including James Belich, Making Peoples: A History of the New Zealanders (1996); Elsdon Best, Māori Agriculture (1925) and The Māori As He Was (1934); and in iwi-specific historical records held by regional museums and iwi archives. Knowledge of natural crossing points and terrain behavior is primarily held by kaumātua and environmental knowledge practitioners and should be accessed through direct engagement with relevant iwi. This knowledge has not been comprehensively documented in published form and consultation is required to access it.↩︎

9. Marsden Point Oil Refinery (Refining NZ) ceased refining operations in March 2022 and converted to an import-only fuel terminal. https://www.channelinfrastructure.nz/↩︎

10. Road surface degradation rates depend on climate, traffic loading, subgrade quality, and original construction standard. In NZ conditions, a chip seal surface typically requires reseal every 8–12 years, and asphalt every 15–25 years. Without reseal, water infiltration causes accelerating subgrade failure. See Transit NZ, “Chipsealing in New Zealand,” 2005.↩︎

11. NZ aggregate resources are abundant and widely distributed. Greywacke is the dominant aggregate source in most regions. See GNS Science, “Mineral Resources of New Zealand,” and regional council aggregate assessments.↩︎

12. Grader productivity estimates based on NZ council road maintenance practice. Actual productivity varies with road condition, width, terrain, and operator skill.↩︎

13. Re-metalling rates for gravel roads vary significantly with traffic volume, subgrade quality, rainfall, and aggregate quality. The 100–200 m³/km/year range is consistent with NZ council practice for low-to-moderate traffic rural roads. Higher-traffic gravel roads may require 200–400 m³/km/year. See NZ Transport Agency, “Unsealed Roads Manual: Guidelines to Good Practice,” 2009.↩︎

14. The extent of Māori land in NZ is documented in records held by Te Arawhiti (Office for Māori Crown Relations), Land Information New Zealand (LINZ), and Māori Land Court (Te Kooti Whenua Māori). Māori freehold land comprises approximately 1.4 million hectares, or roughly 5% of NZ’s land area, distributed unevenly across regions with concentrations in Northland, Bay of Plenty, East Cape, and parts of the South Island. Road corridors across this land are subject to legal access arrangements that do not automatically transfer authority to road maintenance agencies. See Doc #150 for Treaty obligations framework.↩︎

15. The primacy of drainage in road maintenance is well established in NZ road engineering practice. See NZ Transport Agency, “Unsealed Roads Manual: Guidelines to Good Practice,” 2009. https://www.nzta.govt.nz/↩︎

16. Traditional Māori trail networks and terrain knowledge are documented in ethnographic and historical sources including James Belich, Making Peoples: A History of the New Zealanders (1996); Elsdon Best, Māori Agriculture (1925) and The Māori As He Was (1934); and in iwi-specific historical records held by regional museums and iwi archives. Knowledge of natural crossing points and terrain behavior is primarily held by kaumātua and environmental knowledge practitioners and should be accessed through direct engagement with relevant iwi. This knowledge has not been comprehensively documented in published form and consultation is required to access it.↩︎

17. NZ bridge stock is tracked through Waka Kotahi’s Bridge Management Information System (BMIS) for state highways and council records for local roads. The ~18,000 figure includes all road bridges. Exact numbers vary by source depending on inclusion criteria for small culvert structures. See Waka Kotahi, “State Highway Bridge Inventory.”↩︎

18. Steel bridge repainting intervals vary with coating type, climate exposure, and salt-spray environment. Modern industrial bridge coatings (epoxy, polyurethane) are specified for 15–25 year service life in NZ conditions; older alkyd-based coatings degrade faster (8–12 years). Under recovery conditions using locally produced coatings, more frequent repainting cycles should be assumed. See Waka Kotahi, “Bridge Inspection and Maintenance Manual,” and NZ Steel Structures Standard NZS 3404.↩︎

19. NZ timber bridge history: timber was the standard bridge construction material in NZ from colonial settlement through the mid-20th century. The Public Works Department built thousands of timber bridges. See Furkert, F.W., “Early New Zealand Engineers,” 1953, and Ministry of Works historical records.↩︎

20. Timber durability and treatment: radiata pine has low natural durability (NZ Durability Class 4) and requires preservative treatment for structural use in exposed conditions. Macrocarpa (Durability Class 2–3) has moderate natural durability. See NZ Wood, “Timber Properties and Durability.” https://www.nzwood.co.nz/↩︎

21. Timber durability in ground contact: untreated radiata pine (NZ Durability Class 4) typically lasts 5–15 years in ground contact depending on conditions. CCA-treated radiata pine (H5 treatment level for ground contact and fresh water) has demonstrated service lives of 30–50+ years in NZ conditions. See NZ Wood, “Timber Preservation,” and NZS 3640:2003 Chemical Preservation of Round and Sawn Timber. https://www.nzwood.co.nz/↩︎

22. The extent of Māori land in NZ is documented in records held by Te Arawhiti (Office for Māori Crown Relations), Land Information New Zealand (LINZ), and Māori Land Court (Te Kooti Whenua Māori). Māori freehold land comprises approximately 1.4 million hectares, or roughly 5% of NZ’s land area, distributed unevenly across regions with concentrations in Northland, Bay of Plenty, East Cape, and parts of the South Island. Road corridors across this land are subject to legal access arrangements that do not automatically transfer authority to road maintenance agencies. See Doc #150 for Treaty obligations framework.↩︎

23. Timber bridge construction person-day estimates are based on historical NZ practice and contemporary timber bridge construction guides. Actual labor depends heavily on site conditions, span length, and foundation requirements. See NZ Timber Design Guide and historical Public Works Department records.↩︎