Executive Summary

NZ’s approach to Temporary Traffic Management (TTM) is at a critical juncture. A common industry model, where the design of TTM is “bundled” with its physical delivery within a single subcontracted supplier, introduces a potential conflict of interest that can inflate costs and compromise effectiveness. This paper argues that this specific practice, outsourcing both the planning and the execution of TTM to the same external entity, needs reform.

The fundamental issue is that the subcontractor profiting from supplying TTM resources often determines the quantum of those resources. This creates an incentive for oversupply, where commercial interests can overshadow a purely risk-based approach. The result can be an industry perceived as inefficient, eroding public trust and impacting productivity through unnecessary congestion, as highlighted by Auckland’s “road cone mania” discourse and the subsequent 2024 EY report. However, the responsibility for this does not lie with the TTM supplier alone; it is a shared failure when principal contractors and Road Controlling Authorities (RCAs) do not provide sufficient oversight or take ownership of TTM as a critical project component.

This paper is not an argument against contractors developing and maintaining strong, integrated, in-house TTM capabilities. On the contrary, the primary recommendation is for principal contractors to take back control of their TTM supply chain, build internal competency, and own the TTM design process.

The “decoupling” advocated for here is the separation of TTM design from its physical implementation when these services are being outsourced. By having the principal contractor either perform the design in-house or engage a designer independent of the delivery subcontractor, the direct profit motive associated with implementation volume is removed from the planning phase. This fosters objective, risk-based, and right-sized TTM plans focused on achieving the “lowest total risk”.

This paper examines the case for this specific form of decoupling. It defines the problems with the bundled subcontracting model, explores the cost implications, and discusses the benefits of an in house (preferred), or independent (second preferred) design process. It provides recommendations for implementing a decoupled procurement model for outsourced TTM, addressing potential barriers, such as ensuring TMPs remain ‘live’ documents, and weighing the trade-offs. The goal is to present a balanced, evidence-based argument for reforming TTM subcontracting practices, restoring the focus to risk management, and removing perverse incentives to ensure TTM serves as an efficient, effective safety tool with public and industry confidence.

Problem Statement

The bundled procurement of TTM – where the same external subcontractor designs the traffic management plan (TMP) and delivers the on-site setup – embeds a potential conflict of interest. The party determining “how much” TTM is required also profits directly from the resources deployed. Ultimately, three main factors drive TTM costs: (i) the base rates for personnel and plant, (ii) the duration the TTM is required, and (iii) the quantity of personnel and plant deployed. The quantity of resources is the most significant lever for cost, and it is where a conflict of interest has the most impact.

This dynamic can lead to an oversupply of traffic management. However, this only occurs when there is a lack of oversight. The TTM supplier’s power to oversupply is enabled when the principal contractor (or contracting chain as a whole) do not actively scrutinise or understand the TTM being proposed. The symptoms are visible – extensive coning and prolonged speed restrictions, sometimes for minor works. The 2024 EY report for Auckland Council found that prevailing rules could “allow providers to ‘overkill’ projects, profiting from having staff and equipment deployed for as long as possible”.

The transition from the prescriptive CoPTTM to the risk-based NZGTTM introduces a new dimension to this problem. While CoPTTM provided an explicit baseline, the NZGTTM’s emphasis on site-specific risk assessment grants designers more discretion. If the TTM designer is also the TTM delivery subcontractor, there is an amplified risk that risk assessments might be skewed to justify greater quantities of TTM, especially if clients and principal contractors effectively outsource their risk ownership and rely heavily on the TTM subcontractor’s advice.

The converse risk (doing more TTM than is justified because the “rulebook” constraint is looser and the decision-maker profits from volume) is a critical concern that decoupling specifically aims to address in the subcontracting model. Beyond direct costs, this approach has broader impacts. Late TTM integration misses opportunities for safer design, and risks are mitigated by “brute force” (more cones, more staff) rather than smarter upstream choices.

Worryingly, this proliferation of TTM has not correlated with improved safety. Analysis of NZ work zone crash data indicates a rise in deaths and serious injuries, suggesting that simply deploying more conventional TTM is not the answer and may create new hazards. This is compounded by external factors, including deteriorating driver behaviour, which has co-evolved with TTM practices over time.

Background and Context

TTM evolved in NZ under the highly prescriptive CoPTTM, fostering a compliance-first mindset and an industry where TTM could consume 10-15% or more of maintenance project costs. The “road cone mania” outcry and the 2024 EY report highlighted public and political concerns, noting that “contractors have little incentive to work cheaper and faster”.

These incentive structures apply most acutely within the TTM supply chain. Specialist TTM subcontractors, whose revenue is directly linked to volume, face a direct incentive to recommend more extensive TTM. In a bundled subcontracting model where the principal contractor lacks the specialist expertise or contractual levers to scrutinise recommendations, these inflated costs can be passed on. This is a critical nuance: the problem is most pronounced when a principal contractor outsources TTM planning and delivery to a third party without sufficient internal oversight or ownership. This contrasts with international practices like lane rental schemes in the UK, which financially incentivise minimising disruption across the entire delivery chain.

Recent research for Electricity Networks Aotearoa (ENA) revealed alarming trends (2019-2024), including a 208% rise in the average real cost of TTM per day and dramatic increases in cost per kilometre. These rising costs suggest the TTM sector is perceived as lucrative, with profitability potentially stemming from an increase in the cost and quantity of TTM per project. This points towards the TTM supply chain potentially driving demand, a dynamic that decoupling the design function aims to correct.

The regulatory shift to a risk-based approach is pivotal. The NZ Guide to TTM (NZGTTM) and HSWA 2015 champion risk assessment and upstream safety in design. This legal framework implicitly supports early, integrated TTM planning, where the principal contractor takes a leading role. The solution is not ‘structural separation’ but a broader cultural shift towards greater ownership of TTM by principal contractors and clients, supported by collaborative planning, robust monitoring, and assurance. Decoupling design from delivery in the subcontracting sphere is a key enabler of this shift.

Analysis and Discussion

Conflict of Interest and Oversupply in Bundled TTM

The potential conflict of interest in the bundled subcontracting model is not purely theoretical. The Beca (2024) report’s findings of rapidly escalating TTM costs provide quantitative backing. This corresponds profoundly to a commensurate rise in the size, scale and number of TTM sub-contracting firms in NZ (including an explosion of both equity firm ownership of TTM sub-contractors, and multinational aquisions).

Defenders of the bundled model argue that safety obligations and client-approved plans drive TTM setups. While true, these plans often originate from the implementing subcontractor, blurring the lines of objective assessment. This is where collaborative, risk-based pre-planning (e.g., “3Cs” meetings) involving the principal contractor, client, designer, and RCA is crucial to negate this issue. Decoupling aims to clarify this by ensuring the design is genuinely independent of the delivery profit motive, basing recommendations on assessed risk.

If subcontracted design remains coupled with delivery, the shift to a risk-based framework under NZGTTM could exacerbate the issue. Without the prescriptive checklist of CoPTTM, a TTM subcontractor has more scope to define “necessary” TTM through their risk assessment. If a knowledgeable client or principal contractor does not independently scrutinise this assessment, it could justify more extensive setups.

Benefits of Un-conflicted TTM Design and Early Integration

Engaging a TTM designer who is either (i) embedded within the contractor doing the work, or (ii) independent of the delivery subcontractor offers an objective, risk-based perspective. This role can, and ideally should, be an in-house expert within the principal contractor’s team. Their mandate is to protect people and facilitate project success. Unfettered by operational delivery profits, they can explore a broader range of solutions (including, no TTM at all, if that were to be the lowest total risk solution).

Early integration is crucial for Safety in Design (a HSWA requirement) and promotes right-sizing. An un-conflicted TTM planner is better positioned to advocate for the Hierarchy of Controls, proposing solutions like alternative work schedules or different work methods where the risk assessment suggests so, rather than defaulting to personnel-heavy administrative controls.

Critically, this approach facilitates better coordination among all PCBUs. An un-conflicted designer, whether internal or an external consultant, can act as a neutral facilitator in collaborative planning sessions. As observed in practice, when a principal contractor’s internal TM specialists, job owners, and designers collaborate early, the outcomes are often more efficient and effective than when the process is outsourced to a subcontractor who may have conflicting priorities. 

Solutions and Recommendations

To achieve a healthier TTM ecosystem, a multi-pronged approach is recommended, focused on clarifying roles and responsibilities, especially when work is outsourced.

1. Revise Procurement Models for Subcontracted TTM. Clients and principal contractors should structure contracts to separate TTM design from subcontracted This means either performing design in-house (the preference) or engaging a design consultant who is independent of the delivery contractor. This is not to discourage integrated in-house TTM divisions, but to specifically target the conflict of interest in the external supply chain.
2. Embed TTM Design Early. Mandate that TTM considerations are integrated from the project concept phase.
3. Clear Delineation of Roles and ‘Live’ TMPs. Define the “TTM Designer” and “TTM Provider.” Crucially, establish protocols to ensure the TMP remains a ‘live document’. This requires the designer to be involved or consulted throughout the project lifecycle to manage changes, preventing the plan from becoming a static, ‘one-and-done’ document. The TTM Provider’s role must include active monitoring and referral back to the designer when conditions change.
4. Strengthen Independent Review and Assurance. Establish peer review systems for complex TTM plans and use data to validate performance.
5. Industry Capacity Building. Invest in training and certifying TTM designers as a distinct competency. TTM design could be priced based on complexity rather than as a function of delivery cost.
6. Strengthen Collaborative Frameworks. Utilise models like ECI and Alliances. Promote structured, multi-party “3Cs” (Consult, Cooperate, Coordinate) meetings as a standard for all significant projects, ensuring the TTM designer is a key participant.

The following table summarises the anticipated shift:

Trade-Offs

As with any system, there are always trade offs. Decoupling the design from sub-contracted TTM needs to be matched with appropriate attention in the following two areas:

1. Speed vs. Diligence. An independent design step might slow deployment for urgent works, mitigated by pre-approved emergency plans.
2. Flexibility vs. Control. On-site adaptability must be balanced with adherence to the plan. Frameworks for pre-approved variations are needed.

Conclusion

NZ’s TTM practices require transformation. Decoupling TTM design from its physical delivery, specifically when these functions are outsourced to a single supplier, is a crucial step to resolving inherent conflicts of interest and systemic inefficiencies. The current bundled subcontracting model can incentivise oversupply, a risk amplified in our new risk-based regulatory environment.

This reform is fundamentally about driving ownership and capability back to the principal contractor. The ideal model is one where contractors develop strong in-house TTM design and planning competency, integrating it early and effectively into their projects. Where TTM services must be outsourced, separating the design and delivery functions ensures critical planning decisions are made by objective experts, free from the commercial pressures of implementation volume.

While challenges like industry adaptation and ensuring TMPs remain ‘live’ documents exist, they are surmountable with strategic implementation and collaborative frameworks. The potential rewards, safer work zones, reduced public disruption, and more cost-effective infrastructure delivery, are significant. By making this change, NZ can modernise work zone management, ensuring TTM is effective, efficient, and commands public confidence in a system that is right-sized to risk and uncompromising on safety.

References

Beca Limited. (2024, December 4). Assessment of Costs of Carrying Out Works in the Road Corridor for Electricity Distribution Businesses – Report on Findings – Rev B. Prepared for Electricity Networks Aotearoa.

Civil Contractors NZ (Alan Pollard), “Road cone obsession distracts from better safety outcomes,” Media Release, 22 Jul 2024.

Dave Tilton, “The Self-Feeding Organism: How Temporary Traffic Management (TTM) Became Its Own Industry – And Why That Must Change,” LinkedIn Pulse, Dec 10, 2024.

Dave Tilton, “The Unmet Promise of TTM: 20 Years of NZ Work Zone Crash Data,” LinkedIn Pulse, Feb 9, 2025.

Ernst & Young. (2024, July). Report on Auckland Temporary Traffic Management Practices (Hypothetical title based on text references, actual title may vary). Commissioned by Auckland Council.

Federal Highway Administration (US), “Work Zone Traffic Management – FHWA Operations,” (Work Zone Safety and Mobility Rule), (accessed 2025).

ITS International, “Government blitz on ‘disruptive roadworks’ causing traffic jams in UK,” Jan 17, 2024.

Minnesota DOT, “Project Development: Work Zone/Temporary Traffic Control Guidance,” (accessed 2025).

1News Report, “Auckland road cone report: ‘Maximum disruption — maximise profit’,” July 22, 2024.

TransportTalk, “Mayor calls for end to road cone’ mania’, welcomes EY report,” July 23, 2024.

Waka Kotahi NZTA, “Examples of efficient and effective TTM,” 2024.

Waka Kotahi NZTA, “Rolling out the NZGTTM – risk-based approach pilots,” 2024.

WorkSafe NZ, “Introduction to the Health and Safety at Work Act 2015 – Special Guide,” (section 3.8 Overlapping duties).

WorkSafe NZ / NZTA, “NZ Guide to Temporary Traffic Management (NZGTTM),” 2023.