6Preventative maintenance#
6.1Electrical#
Periodic inspections and tests are required on the electrical installation to ensure compliance with the Act. Full inspections and tests are to be carried out at a maximum of five yearly intervals. Where the risk of degradation of the installation due to environmental or other factors is considered high, more frequent inspections are to be carried out. Spot check audits on parts of high risk installations are to be carried out at a maximum of 12 month intervals. Typical high risk factors may include: corrosive environments, susceptibility to flood/submergence, devices nearing end of life, vermin habitats and high pedestrian activity.
Periodic verification of electrical installations is to be carried out in accordance with Appendix C.
Immediate electrical risks (including exposed live conductors, unearthed equipment and incorrect polarity) must be made safe and rectified when discovered and the ESO and Region/District Management notified.
Electrical tests are to be carried out and documented in accordance with the Wiring Rules and AS/NZS 3019 Electrical Installations – Periodic Verification.
6.1.1Point of supply maintenance#
The traffic signal installation is supplied from the electricity entity’s network. Supply can typically be from:
- overhead pole mounted transformer with fuse
- underground pit with fuse pillar box with fuse from an underground supply.
Verification is to include a visual inspection of the point of supply for signs of degradation. Where there is any concern about the integrity of the point of supply or the upstream network, the electricity entity is to be advised.
Work is not to be carried out on electricity entity infrastructure without the express written permission of the electricity entity.
6.1.2Electrical switchboard maintenance#
Maintenance is to be carried out to ensure the electrical integrity of the switchboard. As the switchboard is the point where the traffic signal controller is connected to the supply, it is important that all the components are in good condition.
Inspection is to include but not be limited to:
- ingress of water and vermin
- deterioration of weatherproof seals and other components
- damage by vermin
- detection of poor connections and joints
- correct earthing
- protection against direct and indirect contact with LV terminals/surfaces
- correct internal labelling of components
- correct labelling of field cables.
6.1.3Cable and connection maintenance#
Electrical cabling and connections are to be maintained to ensure a low impedance path for the electricity supply. While traffic signal cable is expected to last in excess of 25 years under standard operating conditions, a number of factors (such as those previously mentioned) can reduce service life. Consequently, visual observations and electrical tests are required regularly.
Where cable temperatures are significantly raised due to poor electrical connections, insulation damage can occur, which may ultimately result in fire. Clean cable termination surfaces, correct fixing tightness and the application of protecting grease to terminations can assist in maintaining the integrity of the termination. Thermal imaging equipment can be used where practical and cost effective to aid early detection of high resistance joints.
Transport and Main Roads Specifications now specify the use of either XLPE/PVC or XLPE/HDPE mains cabling for new installations. PVC/PVC cabling is not designed to be submersed in water for periods of time. The new standard cables are more resilient. Where there is a known water retention problem, the better quality XLPE/HDPE cable should be used to replace PVC/PVC cables that have reached end of life.
The standard PVC/PVC multicore traffic signal cable is not designed to be submersed in water for periods of time.
Rodent and vermin attack as well as poor installation methods can also affect the integrity of the cable sheath. Where damage has occurred, moisture ingress and cable degradation will occur.
Where the rate of insulation resistance degradation reasonably suggests that the cable insulation will not comply at the next regular inspection interval, inspection frequency is to be increased or rectification undertaken.
Inspection items are to include but not be limited to:
- joints, connections and terminations for corrosion
- poor, loose, overheated or unsecured connections
- evidence of moisture ingress to cables and/ or connections
- damaged insulation
- exposed conductors
- general condition of cable
- evidence of rodent/vermin activity
- devices that are not fixed wired are to be tested and tagged
- carbon, soot build-up.
In accordance with the Wiring Rules, electrical tests are to be carried out on cables and results documented.
6.1.4Pits and conduit maintenance#
Pits and conduits are to be inspected visually. Once it has been determined that the conduit installation complies with the required depth, this need no longer be checked except where work to the ground surface has been carried out in the vicinity of the conduit.
Pit lids are to be intact, undamaged and properly fitted to the pit. Pits are to be free of damage, with no collapse of ground around the pit, no collapse of the inside of the pit, and with the pit top level with the surrounding surface. Pits are to be free draining.
Maintenance of pits and conduits is to include but not be limited to:
- ensuring adequate drainage
- replacement of broken or chipped pit lids
- rectifying collapsed pit side walls and other damage
- maintaining ground/pit surface level and pit surrounds.
Cement pits and ducts that contain, or are suspected to contain, asbestos materials are to be handled using safe work practices and qualified persons in accordance with workplace health and safety legislation and Transport and Main Roads procedures. All asbestos materials are to be identified and recorded in Region/District registers.
6.1.5Traffic signal controller maintenance#
Prior to accessing the traffic signal controller, test for touch voltage on the cabinet.
Traffic signal controllers are to be inspected visually. The controller is to be clear of vermin, particularly geckos in the control equipment, and ants and spiders in the base. The joint between the concrete base and steel plinth is to be sealed and the incoming conduits are to be filled with sealant.
The electrical integrity of components is to be checked.
Maintenance is to include, but not be limited to:
- ingress of/damage by water and vermin
- deterioration of weatherproof seals and other components
- adequate ventilation
- detection of poor connections and joints
- correct earthing
- protection against direct and indirect contact with LV terminals/surfaces
- correct internal labelling of components
- correct labelling of field cables.
6.1.6Pushbutton/audio tactile sounder maintenance#
Pushbuttons are to be inspected visually for signs of deterioration, damage and vandalism.
The button mechanism is to operate freely and the internal microswitch is to function appropriately.
Cables are to be to standard and be terminated correctly.
Inspection is to include but not be limited to:
- vandal damage
- deterioration of weatherproof seals and other components
- correct termination of cables
- correct earthing connections
- checking of all accessible fixings for tightness.
6.1.7Lantern/aspect maintenance#
Periodic verification of the lanterns is required to ensure continuing electrical safety.
Maintenance is to include but not be limited to:
- a visual check of the electrical components and wiring for signs of overheating
- checking of all accessible screws, nuts and fixings for tightness
- correct earthing connections.
6.1.8Other equipment maintenance#
Where other permitted electrical equipment, (for example CCTV camera) is connected to traffic signals installations, it is to be checked for electrical safety and be fused with an HRC fuse no greater than 3A for discrimination.
6.2Structural#
Periodic visual inspections are to be undertaken to ensure at least the following items are examined for compliance with the relevant standards:
- steel poles
- other lantern supports (for example, secured to structures).
Inspections are to be carried out ten years after original installation and then every five years thereafter. Environmental conditions to which the traffic signal installation is subject may require the frequency of inspections to be increased - for example, bridges/overpasses, corrosive environment and areas prone to flooding.
Structural inspections are to be completed in accordance with Structures Section requirements.
6.2.1Steel pole maintenance#
Generally once steel poles have been installed and commissioned, minimal maintenance is required.
However, the following aspects are to be inspected as a minimum:
- testing the thickness of galvanic protection at the pole base and other areas in accordance with AS/NZS 4680
- pole vertical alignment tolerance check
- surrounding area assessment.
Traffic signal poles including combination mast arms and joint use poles can suffer damage from both major and minor incidents. They are to be replaced when any of the following damage is evident:
- horizontal cut(s) or tear(s) exist and exceeds 20% of the pole circumference, or
- deformation of pole due to impact exceeds 20% of the pole diameter, or
Where sharp edges are present, but it is not considered necessary to replace the pole, the edges are to be rectified to remove the risk of personal injury. Where hatchway doors and/or fixings are damaged and can be replaced without the need for replacing the pole, the damaged part(s) are to be replaced.
Welding on poles is only to be undertaken at the initial pole fabrication stage. No additional welding of poles is to be undertaken.
6.2.2Steel post maintenance#
Where steel posts are damaged, degraded, or corroded, they are to be replaced.
6.3Environmental#
The maximum interval between inspections is 12 months. Where particularly detrimental environmental conditions require – for example, corrosive environment and areas prone to flooding – more frequent inspections are to be carried out.
6.3.1Vegetation management#
The growth of vegetation near lanterns has the potential to significantly reduce the effectiveness of traffic signal installations. Where vegetation or other obstructions have, or may have an impact on signal performance, they are to be removed or otherwise treated to remove the risk.
Vegetation may increase the likelihood of vermin and/or hinder access to switchgear and electrical pits and is to be managed accordingly. Concrete surrounds should be installed around equipment, particularly switchboards.
6.3.2Vermin#
Evidence of vermin infestation is to be removed, and damage caused by vermin is to be rectified. The installation is to be treated/modified to prevent/minimise the likelihood of reinfestation.
6.3.3Maintenance access#
Where necessary, access to sites is to be remedied to allow safe, all-weather access by maintenance personnel.
6.3.4General tidy up#
Each site is to be cleaned of all waste/rubbish so as to present a clean, tidy area that reflects well on Transport and Main Roads.
6.3.5Cleaning and painting#
The controller, poles, posts, mastarms and associated hardware are to be cleaned and posters and graffiti removed. Where paintwork is damaged or has deteriorated, it is to be repainted.