THE UK’s congested and snow-hit traffic has had another obstacle to deal with: falling LED street lights.
The authority which runs the country’s roads, Highways England, has issued a warning about lanterns dropping off their columns and falling in front of traffic, leading to delays and jams.
In one incident in Wellingborough, Northamptonshire, a 6kg Philips Iridium2 canopy parted from the rest of the lantern and plunged 12 metres onto a car windscreen. No-one was injured.
In another accident, a falling luminaire came to rest in a lane of the M62 motorway which was closed off at the time.
Highways England said it was aware of four luminaires will fell on its roadways since the start of the year. To date, there have been no injuries to motorists or road workers.
The Wellingborough mishap occurred on the A45 and A509 roundabout, where the speed limit is 40mph.
The rest of the lantern was recovered and it was discovered that the canopy clip ‘spring’ was weak permitting excessive play.
Further investigations are planned to identify if this is an isolated or wider problem, and, whether the spring was weakened as a result of falling to ground.
Highways England warned that all sections of the roads network where this type of luminaire are installed should be scouted to identify units at risk of separation failure.
Where a failure is identified on a section of the network, a ‘risk-based approach’ should consider which action is required.
The other falling luminaires – which occurred in three different parts of the country – were the Philips Luma and the Urbis-Schreder Ampera Maxi.
The Ampera Maxi failure manifested itself when the bolts holding the luminaire to the spigot adapter sheared.
There was evidence to show that the unit hung by its electrical cabling before falling. Subsequent ground level inspections indicated the units droop by 15 degrees prior to falling.
The Philips Luma failure gave no pre-warning, says Highways England. Subsequent investigation and examination did however show signs of thread wear.
The underlying cause of the bolts failing and loosened bolts is under investigation as a matter of priority by technical experts as well as the manufacturers.
Highways England recommends that all sections of the network where Urbis-Schrader Ampera and Philips Luma 2 and 3 are fitted are to be subject to a higher level of inspection than normal to identify fallen, hanging or drooping luminaires.
It has asked traffic officers to be vigilant for drooping lanterns and report them to the maintenance provider.
It has ordered that any compromised luminaires are to be removed within 24 hours. If there is more than one compromised unit in a location, ‘consideration must be given to remove further units in that location’.
In a statement, Philips Lighting told Lux:
'Highways England notified us recently that a Philips Luma3 street lighting luminaire on the Highways England network had fallen down. We are still investigating the reported incident. In order to perform a proper analysis, we need to be able to investigate the fallen luminaire, which to date has not been returned to us.
'Earlier this year Highways England informed us that a Philips Iridium2 canopy fell to the ground and confirmed that it doesn’t believe this stems from a manufacturing issue.
'As a precautionary measure we recommend installers to assure maintenance and installation activities are carried out as described in our manual specifically regarding the torque to be applied.
'Ensuring the health and safety of our customers and the general public is our top priority.'
Urbis-Schreder said the Ampera Maxi failed due to the left-hand bolt developing tension to secure the joint. The fact that tightness was not developed in the right-hand bolt could be due to either incorrectly tightening the bolt or seizure of the screw in the body giving the impression it was tight.
It said lanterns that have drooped should be replaced as the teeth will be damaged and the securing bolts subjected to abnormal loads.
Replacements would be provided for lanterns reported to have drooped. Lanterns that have not drooped can be considered satisfactory , as if the joint between the mounting socket and the luminaire is not tight the luminaire will droop very soon after installation.
- Luminaire safety and column integrity is one of the topics to be covered at the Lighting for Transport and Infrastructure Conference which is co-located with the LuxLive 2018 exhibition at ExCeL London on Wednesday 13 November and Thursday 14 November 2018. The event is free to those will a lighting estate to manage. Register here.