The new lighting scheme for Bristol’s iconic Clifton Suspension Bridge across the Avon Gorge is visually spectacular – but also needed to navigate considerable practical and operational challenges.
By Harriet Davis
Grade I listed, with a 200+ metre span across the Avon Gorge, and one of Brunel’s most recognisable feats, the Clifton Suspension Bridge is a working piece of infrastructure and, of course, an iconic landmark in Bristol.
We at Hoare Lea were privileged to be given the brief to upgrade the existing lighting, taking the design from concept through to installation.
This formed part of a major repainting maintenance project for the bridge. The existing lighting was nearing the end of its life, and compromised a patchwork of LED, fluorescent and halogen units, all of which were becoming increasingly costly to maintain. The new scheme therefore had to be many things, but notably:
- A heritage, sensitive lighting design inspired by Isambard Kingdom Brunel.
- An operationally robust scheme that accounted for a live transport route connecting Clifton to Leigh Woods, for pedestrians, cyclists and motorists.
- Glare-considerate, with CCTV cam-eras monitoring the deck 24/7.
- Ecologically considerate to Leigh Woods’ forestry and local bat activity.
- Maintainable, with as few fixtures as possible in hard-to-reach locations such as the chains.
We also had to respect the bridge’s idiosyncrasies. For example, the towers were built differently, one shorter and one chamfered. The bridge’s structure also naturally moves and vibrates, especially in high winds. Given these challenges, from the outset we based decisions on four key pillars:
- Energy. To give the client visibility on consumption and explore opportunities for efficiency and renewable energy.
- Architecture. Letting the bridge be the hero. Lights should be either concealed or appear as if it had always belonged to the fabric of the building.
- Maintenance. Reducing the extent of fixtures on the chains, favouring the deck or tower locations with safer, simpler access for the onsite team.
- Flexibility. Creating layers of light and scenes. With warm white light as the everyday option and the ability to introduce colour and vary emphasis for special occasions.
DIFFERENT PROPOSALS
We sketched, modelled and calculated a variety of different lighting proposals, knowing accuracy would be limited by the existing fabric of the bridge, its natural movement, geometry and material variances.
We also undertook multiple night trials onsite, testing different fittings by various manufacturers, altering the optics, mounting heights and offsets.
The onsite trials did two jobs. First, they let us judge the visual effect. Second, they allowed the design team and manufacturers to test brackets and clamps and propose cable routes against the bridge’s tolerances.
There were multiple layers to our lighting strategy so as to create flexibility within the scheme and put an emphasis on different key parts of the bridge’s fabric. These needed to include adding lighting to the walkways and to the chains, lighting the ‘hangers’, lighting the towers, and implementing a new lighting control system.
LIGHTING TO THE WALKWAYS
Within the previous scheme, fluorescent fixtures provided a glow along the deck and parapets, visible from both the walkway and afar.
We wanted to maintain this type of illumination but refine the lighting treatment by splitting it into two, keeping a functional lighting treatment and a dedicated feature lighting treatment that highlighted the outer guardrail.
For the functional lighting treatment to the deck, we explored several fixtures that could be located along the guardrails. But, ultimately, we needed something robust, reliable and that reduced the amount of product where feasible.
Following concept development, we moved forward with an asymmetric wall light proposal, developing a bespoke housing for it in collaboration with Designplan.
This fixture was adapted to clamp to the existing guardrail and sit behind the security mesh. Several iterations were required to accommodate the size restrictions of the bridge and curvature of the mesh panels. Through trials we further modified the angle of the beam, to intentionally separate the beam from the road and the walkway, by ensuring the cut-off was just below the top of the upstand to the deck.
Custom backplates were supplied as a separate item, in a different material to reduce the extent of metal contact to the bridge. These were then externally finished to blend into the bridge, with an internal black finish to suppress light spill.
The second part of our lighting treatment to the walkways was to highlight the latticework on the guardrails, by grazing light across the metalwork.
After, again, carrying out a set of trials with various mounting points, an uplighting effect from the bottom of the guardrail panels gave the most consistent lit impression.
By utilising a baseplate with the fixture clamped to the base of the guardrail panels, drivers and cabling could be routed under the bridge for simpler maintenance and to keep components out of public view. We used a narrow-beam optic, with a glare strip located on the outer side to keep light contained to the bridge.
LIGHTING TO THE CHAINS
We explored many approaches for the illumination to the chains: lighting from within, below, above or from the sides.
The key challenge was that the chains moved a lot, however there was potential to utilise individual links of the chains which remained as one. The best balance of visual impression both up close and at distance came from a top-mounted downward-lit impression.
In collaboration with Studiotech, we therefore designed a bracket that clamped to the top chain link, offsetting the luminaire to allow light to graze down the face of the chains. The bracket had a retaining lip and was finished matched to each chain side so it visually ‘disappeared’ during the day.
Cabling and drivers were the other half of the equation. To avoid heavy cable runs, we utilised a GDS DMX drive hub system in the towers; the drive cards fed smaller cables to fixtures, minimising volt drop without upsizing cables across 100m lengths.
We also wanted to minimise any cable presence within the chains to aid with long-term maintenance.
LIGHTING TO THE HANGERS
The ‘hangers’ (or the joints that come down from the main suspension cable to support the roadway) had been previously lit by the former Guide Lite system, prior to the 2006 scheme.
We wanted to reintroduce them in a subtle way, to visually stitch together the parapet and chains. Different methods of illumination were explored, as a variety of different lighting effects could alter how we would perceive the hangers.
For example, we considered pixel-controlled fixtures, linear lighting and node lighting. But in the end we determined that this would take away from the natural architecture of the bridge.
Trials ruled out inground uplights, which were too inconsistent and high-level downlighting, which gave a good effect but would be difficult to access.
The sweet spot was midway upwards, with paired luminaires either side of each hanger: this captured the hanger faces and picked out the underside of the chains. This also created a three-dimensional effect, while keeping the fittings in line with the bridge so they didn’t intrude on the walkway or carriageway.
Because these are within reach from pedestrians, we had to ensure the fittings had a tamper-resistant housing that we, again, designed in collaboration with Studiotech.
The fixtures also had to clamp around the hanger base, with as minimal fixings visible as possible; a simple form blends into the bridge’s fabric, and accounts for simple maintenance, removability and vibration.
Power routing became its own small feature from this fixture, a Y-shaped conduit following the rhythm of the upstand’s roadside, echoing the bridge’s engineering language.
The hanger lighting treatment is applied to roughly two-thirds of the hangers; near the centre of the bridge the hangers shorten, and the effect becomes visually tight, so we stopped before it felt over compressed.
LIGHTING THE TOWERS
A series of treatments make up the illumination to the towers. Perimeter wall lights were upgraded to LED while maintaining their original appearance and effect, to minimise work where no changes were needed.
On the outer elevations, further trials led us to use linear grazers in two rows: an inner row to lift texture on the brickwork, and an outer row to wash higher up the towers.
As these sit in public thoroughfares, we undertook anti-slip surface requirements on the luminaire covers whilst balancing the visual impression.
Inside the lower arches, we pivoted several times during design development. Inground luminaires (continuing from the external lit impression) within the roadways clashed with the narrowed carriage-way and water channels that would collect debris.
Low-level bracket-mounted light-ing invited impact from vehicles and cyclists and high-level uplights read with a hard ‘start line’. We ultimately used slim, wide-beam linear fixtures mounted vertically in the tower recesses, cross-grazing to produce an even wash through the arches, with louvres that mitigate glare and keep light contained within the reveals.
The upper archways were simpler, and out of public reach, so we used uplights on unistrut, fixed clear of maintenance routes.
The inner window reveals retained their gentle highlight, which we upgraded to LED with RGBW capability for consistency with the broader system.
A favourite and final new layer of light was to the tower cornices. Previously unlit, they now visually tie in with the chains and towers and can be seen from right across Bristol.
We used the same fixture family as the chains for visual consistency, with a wraparound clamp bracket that grazes the façade and catches the underside of the crowns. These were, again, clamp only, with no invasive fixings.
LIGHTING CONTROLS
On a structure with almost no places to hide fixtures we designed the system to be visible yet disciplined. So, all neat runs, minimal surface clutter, and controls located in accessible areas.
With a predominantly RGBW lighting scheme, as this scheme is, we explored wireless controls to reduce cabling, improve maintainability, and align with a spirit of innovation – an approach we think Brunel would have appreciated!
Fixtures are all fitted with addressable nodes for remote monitoring and control, enabling dynamic colour when required for special occasions, while the default is a classic warm white that feels true to the fabric of the bridge.
OTHER KEY CONSIDERATIONS
Throughout the design development process, we tuned outputs and optics to contain light to the bridge, reduce upward spill, and limit disturbance to bats and ecology in the adjacent woodland.
Every lighting layer was reviewed against the CCTV camera sightlines to reduce glare and obstruction. This ensures there is always security and the safety lighting remains functionally independent, so it can operate through darkness without being compromised by feature lighting scenes.
We materially reduced equipment on the chains and concentrated more fittings on the deck and towers, where access is easier and quicker. Brackets are clamp-based and non-invasive yet secure, with consideration for movement, vibration, and tamper-resistance. Drivers and hubs are centralised where possible to simplify replacement and diagnostics.
CONCLUSIONS
In summary, we wanted the scheme to be layered and flexible, a composition that can be subtle, ceremonial, or civic, without overpowering the architecture.
Designing for the Clifton Suspension Bridge meant, of course, accepting this venerable bridge on its own terms: its motion, asymmetry, and that it is very much a piece of Bristol.
We lit it to enhance rather than announce, to be maintenance-savvy, ecology minded, and quietly capable of spectacle when needed.
If ‘difficult lighting challenges’ teach us anything, it is that a lighting design on a heritage structure can look simple.
But it will – almost certainly – have gone through vigorous trial and error to create a design that visually enhances the structure as it is without making the lighting the star of the show. Which is, of course, as it should be.
Harriet Davis BSc is principal lighting designer at Hoare Lea
PROJECT CREDITS
Client: Clifton Suspension Bridge Trust
Lighting design: Hoare Lea. Harriet Davis, principal lighting designer – lead, Brad Joseph, senior associate, Dominic Meyrick, director, Juan Ferrari, director
Electrical design: Hoare Lea. David Woolley, director
Project manager and structural engineers: COWI
Electrical contractor: Darke & Taylor
Main contractor: Taziker
Lighting specified: Designplan, Optelma, Studiotech, Griven, Thorn, Bega, MyMesh
Photographer: Dan Paton
Image shows the new lighting scheme for the Bristol Suspension Bridge, by Dan Paton.
This is an abridged version of the article that appears in the July/August edition of Lighting Journal. To read the full article, simply click on the page-turner to your right.
