A significant amount of state highway maintenance cannot be carried out during daytime hours due to high traffic flows and lack of suitable detours. Some specific construction processes for new roads, such as some concrete pours, are required to be continuous and therefore also require night works. This page provides guidance on how to identify when it is necessary to undertake works at night and additional controls that may be required.

There is no set rule to when night works are necessary, as there are many factors to consider. Night works are more likely to be required for maintenance of existing roads than construction of new roads. Maintenance works can be classified into two groups: routine and periodic maintenance.  Routine maintenance will generally happen during the day, although occasionally night works will be necessary. Periodic maintenance works such as resurfacing are more likely to require night works. Thin Asphalt Surfacing work is one of the most significant night-time maintenance noise issues, particularly if the existing pavement requires milling.

For maintenance works the most important factor in determining whether night works are required is the traffic volume. Other factors to consider include the method of works/closure, possible detours, predicted noise levels, timeframe for works, and safety aspects. The traffic volume is important because of the difficulty in minimising delays with high traffic flows. If there is no suitable way to limit traffic disruption and delay during the day then night works may be required.

Night-time road construction and maintenance works will probably be necessary if:

• Congestion prevents daytime maintenance (information about congestion is available from the NZTA Area Engineer), or
• The window of opportunity for daytime works is too short (this will depend on: the nature of the maintenance works, i.e. type, duration, safety issues, etc; congestion, site and traffic characteristics), or
• The construction process is continuous (such as some concrete pours).

Before confirming that night works are required, it should be evaluated:

• What options are available to avoid working at night?
• If there are options, are these technically and economically feasible?

Robust consideration of these questions is required to justify night works. It is important that this evaluation process takes into account all the affected users/stakeholders both locally and regionally to produce an outcome that has the least overall impact to stakeholders.

Noise limits

During the day, most people tolerate higher noise levels from temporary activities, compared to permanent activities. Therefore guideline limits for temporary construction and maintenance activity are higher than noise limits that normally apply to permanent activities. However, at night the guideline limits are similar to those for permanent activities, to prevent sleep disturbance.

Predictions should be made to determine what construction noise level is practicable to achieve for night works. For most works the guideline noise limits in NZS 6803 are not achievable at night. However, if night works are justified, and enhanced management and communication procedures are implemented, then it will usually be considered reasonable for construction noise to exceed the NZS 6803 guidelines. An alternative noise limit that is reasonable and practicable should be adopted.

Ideally, the noise limit adopted for night works will be included in consent or designation conditions. However, if this is not the case then the justification for night works and the limits must be agreed with the regulatory authority (council). Once agreed the limits adopted should be recorded in the Construction Noise Management Plan.

Mitigation

Standard construction noise management and mitigation methods are detailed on other pages in this web site. For most night works, enhanced noise management measures will be required, although this is dependent on the scale of the project and the number of stakeholders potentially affected. For example, if the area around night works is uninhabited then there is unlikely to be any noise effect and therefore no additional noise management or mitigation should be required. However, night works in the middle of a residential area will require careful management.

The main noise effect of undertaking road construction and maintenance at night is sleep disturbance. Where practicable, works should be programmed so that all noisy work is undertaken earlier in the night to avoid sleep disturbance.

For night works in particular, people tend not to be disturbed so much by the lower frequency continuous noise from machine engines, but do get disturbed by noises such as reversing beepers, whistling, banging tailgates or shouting.

In addition to standard good construction noise management, when conducting night works it may be necessary to:

• Increase the frequency of communications with stakeholders.
• Conduct regular noise monitoring to ensure adopted noise limits are achieved.
• If unreasonable noise levels cannot be avoided then neighbours may be offered temporary relocation.