So, not simple or straightforward
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.
Design considerations for new column designs
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.
Our top tips:
- Ensure the structure is not overloaded, given the weight and wind area for the attachment
- Check electrical load is covered:
- What is your method for attaching and gaining (where required) an electrical connection?
- Does the column have the correct type of electrical supply (in compliance with the IET Guide for Electrical Street Furniture)?
- What is the energy payment? (most columns are un-metered)
- Where relevant, have you ensured the equipment is fail-safe in the event of a column collision (electrically safe and transmitting antennae isolated)
- Have you ensured contact details for unscheduled maintenance and emergency call outs, is recorded against the asset (in the asset database)? For example. In the event of the column being struck by a car who is called to deactivate the equipment and make it safe, prior to repairs?
- Are suitable warnings evident for those accessing and maintaining the luminaire and other attachments? Ensure workers are aware of any access restrictions resulting from each of the pieces of equipment on the column. e.g. arranging for an outage to turn off transmitting antennae and ensuring suitable insurances are in place
Tool kits for asset owners
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;
- Well-lit highways;
- Management of highways structures; and
- Well maintained highways
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:
- Determine stock condition for financial planning
- Identify problem columns and trends
- Develop intervention strategies based on agreed Service Levels (Life Cycle Planning)
Asset management is now the core consideration
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.