How to: ensure your columns are Smart City 'fit'
The modest lighting column has graced our streetscape for centuries. Yet, it’s only now, with the advent of ‘Smart City’s’ that we are starting to realise their full potential.
Allan Howard, Technical Director of Lighting & Energy Solutions at WSP, recently contributed to our educational technical seminar programme. Sharing with us his work (with the ILP) on the Humble Lamppost project: which encourages us all to start thinking of columns as minor structures.
So, how do we ensure lighting columns are future-ready, meet the needs of data-hungry local authorities and the loading requirements of EV charging, noise and pollution sensors?
Assisting lighting column asset owners, contractors, consultants and utility providers who wish to use lighting column infrastructure to enable the delivery of Smart City services, his popular paper1 highlighted the key issues when checking the suitability of equipment and obtaining permissions and approvals for attaching new assets2.
We’ve summarised the key points below:
There is increasing pressure on lighting column asset owners for new equipment to be added into the street scene. Each of these could be added on its own column or support. However, under ‘Well Managed Highway Infrastructure – A code of practice’ there is a strategic move towards reducing roadside clutter. This encourages equipment to be added to existing structures such as lighting columns but critically, these must be structurally assessed beforehand, with broader planning and approval issues resolved.
Lighting columns have been designed specifically for the luminaires and signs that are attached to them using British and European Standard BS EN 40 Lighting Columns3. The design criteria of the column will also vary by location in the UK as outlined in PD 65473.
The economic pressures on authorities and contractors to deliver - for less cost - has inevitably meant that safety margins on scheme designs have been reduced to the minimum requirements: some columns will therefore not have the spare structural capacity to allow for new attachments to be added.
It’s simply not possible to visually inspect a column to confirm whether a new attachment can be added safely and so, a design calculation is required to show the lighting column still meets BS EN 40 with the proposed attachment(s) in place.
Guidance for ‘seasonal’ is provided in ILP Professional Lighting Guide 06 Guidance on the Installation and Maintenance of Seasonal Decorations and Lighting Column Attachments. But similarly, where the equipment requires the column to be modified, for example drilling a hole for cable access, reduced structural capacity of the column (due to hole size and location) must be calculated for inclusion in the design checks.
The durability of the lighting column must be considered including protection against corrosion and moisture ingress.
Finally, the implications of adding equipment to passive safety columns should be considered and is not recommended without specialist advice, as the attached equipment may be required to have a level of passive safety.
The key impact of adding new attachments is the effect on the additional wind area (and for offset attachments, the additional weight) on the structural stresses within the lighting column. By considering the shape and size of the attachment, we can minimise the effects and increase the likelihood of acceptance in the design phase: the trick is to choose form factors that are more aerodynamic - circular and smooth shapes will have a lower impact than square boxes or flat plates.
Secondly, ancillary equipment, sometimes required at the base of the column, often need a cabinet to protect and secure the electrical equipment. The feasibility of adding the equipment to the column will depend on the available space and pedestrian and vehicular access requirements in that location.
Looking forward, it’s clear that columns will need to support and facilitate a range of additional attachments over the ‘normal’ signage and hanging baskets. Designers and specifiers will need to make these considerations and indicate the requirements within their PD65474 specification. For example, to accommodate Smart technologies, we’re being advised that a column should support a 0.3m 2 sign located at its top.
A lighting column, as a structure, must have someone responsible for its ownership and condition. As such there is a need for an approval and licence issuing process in order to attach new equipment.
At this critical time of change, there have been several new guidance and support documents issued to help owners understand their assets:
A new code of practice
A new Well Managed Highway Infrastructure Code of Practice (CoP) came into force in October 2018 superseding 3 existing codes;
The CoP has been developed through consultation with practitioners, professionals and user groups and was approved and published by the UK Roads Liaison Group (UKRLG).
The CoP is a change in approach, whereas the current documents contained 222 recommendations between them and are not risk based. The new CoP focusses on understanding the highway asset condition and delivering a risk and asset management-based service built upon 36 recommendations.
ILP Guidance, Note 6
Retrofitting LED luminaires on existing lighting columns
To support the new code of practice, in June 2019, the GN22 Asset-Management Toolkit: Minor structures (ATOMS) was launched at the ILP Summit. This now replaces the TR22, and can be used to help with the following:
In 2017 NDT test houses reported an average 3.5% of columns that were red/critical columns, with a growing number of amber assessed columns (2010-11% to 2016-37%). Furthermore, 10% of amber columns have turned red over 3 years. In response, PFI’s have been replacing approxinately 80% of their authorities’ stock over a five-year investment period: understanding your asset has never been more important.
In summary, our perspectives on columns need to shift to allow for the multitude of new roles they will play in the future streetscape. Requirements are changing and future column design will have to take this onboard, to ensure they are safe and fit-for purpose for their new, more prominent role: but when seen (and managed) as minor structures, columns can become the central infrastructure our Smart Cities need.
1 Paper available in full here >
2 The approvals and permissions will depend on who the asset owner is
3 Or its superseded versions e.g. BS 5649
4 PD6547:2004+A1:2009 Guidance on the use of BS EN 40-3-1 and BS EN 40-3-3