Lighting Design Knowledge Centre

BS 5489 is the British Standard used in the UK to support the design of road lighting. It provides recommendations for selecting suitable lighting classes and applying the requirements of the BS EN 13201 series to roads, streets, pedestrian areas and other external public spaces.

The correct approach is not simply to select the brightest class. The designer considers factors such as road use, traffic characteristics, speed, pedestrian activity, conflict areas, crime risk, environmental setting and the requirements of the relevant highway authority. The selected class then establishes the lighting performance that the design calculations must demonstrate.

A Section 38 agreement is commonly used where a developer intends new roads within a development to become publicly maintainable highways. The agreement is made with the local highway authority and covers the construction, approval and future adoption of the roads.

Where lighting is required, the Section 38 submission normally includes an adoptable lighting layout, calculations, equipment details, electrical information and coordination with highways, drainage, utilities, trees, parking and private property. Early design coordination helps reduce conflicts and supports a smoother technical approval and adoption process.

A Section 278 agreement allows a developer to fund and carry out works within an existing public highway. Typical works include new or altered junctions, accesses, crossings, traffic islands, carriageway widening and associated highway infrastructure.

Lighting may need to be extended, relocated, upgraded or redesigned as part of the highway works. The design must respond to the changed road geometry, the authority's specification, existing assets, electrical supplies, safety requirements and the effects on surrounding properties and environmental receptors.

Road-lighting classes define measurable performance requirements for different applications. M classes are principally associated with motorised traffic routes, C classes are used for conflict areas where traffic streams interact, and P classes are generally associated with pedestrians and low-speed traffic in areas such as residential streets, footways and cycle routes.

The class is selected after considering the purpose and risk profile of the area. Calculations then assess the relevant criteria, which may include luminance, illuminance, uniformity, glare and surrounding illumination. A suitable class provides the required visual performance without unnecessary energy use or environmental impact.

P1 is one of the P lighting classes used for pedestrian and low-speed environments. It represents a comparatively high level of performance within the P-class range and may be considered where the assessment identifies demanding visual, movement, safety or security requirements.

P1 should not be applied automatically to every residential or pedestrian route. The class should be justified using the relevant selection process, local authority policy and site-specific risk factors. Lower classes may be more appropriate where activity and risk are reduced, helping to limit energy consumption and light spill.

M3 is an M lighting class used for motorised traffic routes where the road and traffic assessment supports that level of performance. M-class design is primarily based on road-surface luminance and also considers overall and longitudinal uniformity, glare control and the illumination of surrounding areas.

The selection of M3 depends on factors such as traffic flow, speed, road layout, junction frequency, parked vehicles, ambient brightness and the complexity of the driving task. The designer should document why the class is appropriate rather than relying only on the historic lighting level.

TA 501 is part of the Design Manual for Roads and Bridges and provides a structured method for assessing road lighting on the strategic road network. It supports evidence-based decisions on whether lighting should be provided and whether existing installations should be retained, modified, renewed, dimmed, partially decommissioned or removed.

The assessment considers matters such as road safety, traffic and collision information, route characteristics, operational requirements, environmental effects, energy, maintenance and whole-life costs. It is an appraisal process rather than simply a calculation of lighting levels.

A Lighting Impact Assessment examines how proposed exterior lighting may affect the surrounding environment. It is often prepared to support planning applications where lighting could influence nearby homes, rural landscapes, protected habitats, dark corridors, highways or other sensitive receptors.

The assessment may describe the baseline conditions, applicable environmental zone, proposed lighting strategy, likely light spill and obtrusive-light effects, ecological considerations, controls, mitigation and indicative calculations. Its purpose is to show that lighting can meet the operational need while avoiding unnecessary impact.

ILP Guidance Note GN01 provides guidance on reducing obtrusive light from exterior lighting installations. It describes environmental zones ranging from intrinsically dark landscapes to high-brightness urban areas and gives recommended limitations for effects such as light entering windows, source intensity and upward light.

The environmental zone should reflect the actual surroundings and planning context. Responsible design combines suitable equipment, mounting heights, optical control, aiming, dimming, curfews and verification calculations rather than treating a single numerical limit as the complete solution.

Correlated colour temperature describes the apparent warmth or coolness of white light and is expressed in kelvin. Lower values such as 2200 K or 2700 K appear warmer, while 3000 K and 4000 K appear progressively cooler.

There is no single colour temperature suitable for every project. The selection should consider the visual task, highway or client specification, local planning policy, existing lighting, landscape character, ecology, residential amenity, product performance and energy use. In environmentally sensitive locations, warmer light and careful spectral selection may form part of a wider mitigation strategy.

Bats use dark roosting, commuting and foraging habitats, and different species can respond differently to artificial light. Lighting close to roosts, woodland edges, hedgerows, watercourses and connected habitat should therefore be informed by ecological advice and the sensitivity of the site.

Mitigation may include retaining dark corridors, moving luminaires away from sensitive features, reducing mounting heights or output, using suitable optics and shielding, controlling operating hours and selecting an appropriate spectrum. Lighting calculations should demonstrate the predicted effect at the ecological receptor rather than relying only on equipment descriptions.

Lighting calculations are produced using specialist design software and verified photometric data for the proposed luminaires. The designer builds a model using the road, path, car park or site geometry; mounting heights; column positions; luminaire arrangements; surface properties and the calculation grid required by the applicable standard.

The software predicts lighting performance across the model, but the result still depends on sound engineering judgement. The designer reviews compliance, glare, uniformity, light spill, equipment practicality, electrical coordination, maintenance, environmental effects and the limitations of the input data before issuing the design.