Good lighting design is essential to the functional operation and differentiation of spaces, within and around railway stations and transport interchanges. It can reveal and enhance the architecture, create legible spaces and promote passenger safety while ensuring ease of movement and equal access for all user groups.
When considering how a station environment should be lit, it is important to first define the visual tasks and how the lighting should address them. Lighting should be layered and task-specific, rather than generic and undifferentiated, as it is widely accepted that visual information is processed using a brightness and contrast hierarchy within the visual field.
Horizontal illuminance and lighting uniformity should never be the sole consideration because the way in which the eye responds to light does not correspond with linear illuminance scales where a range of visual step changes should be applied.
To give a perceptual difference with ambient illuminance levels, recommended step changes in illuminance are illustrated below:
In both interior and exterior environments, consideration should also be given to levels of illuminance of the immediate area surrounding the task area together with the background ambient illuminance. This is to avoid extreme variations in illuminance that may cause visual discomfort, particularly for the elderly and the visually impaired.
The illuminance of the immediate surrounding area shall be related to the illuminance of the task area and should provide a well-balanced luminance distribution in the visual field. The immediate surrounding area should be a band with a width of at least 0.5 metres around the task area within the visual field.
When standing or walking, the visual field includes more vertical surfaces than horizontal ones. In transport environments passengers are naturally drawn to brighter vertical backdrops rather than brighter floors or table surfaces, whilst either moving or standing. Indirect lighting and wall washing therefore place greater emphasis on the ceiling and vertical surfaces rather than the floor surface.
A number of priorities and strategies will concern designers in their approach to lighting the public areas of stations.
Orientation and safe movement – passengers are often unfamiliar with the environment and wayfinding decisions will need to be made quickly to avoid congestion, particularly at transition points, thresholds and changes in direction.
Hazard identification – obvious hazards include changes in level, junctions, changes in direction, platform edges and areas where there are moving vehicles or equipment. Local accent lighting should be used where necessary.
Wayfinding – this can be considered in four distinct stages: ‘orientation’, ‘route decision’, ‘route monitoring’ and ‘destination recognition’. Signs, directory panels and maps should be adequately illuminated. Enhanced levels of illuminance provided in decision-making areas and at destination points will assist passengers’ decision-making process.
Safety and security – appropriate illuminance levels with good levels of uniformity should be provided both internally and externally in transport environments. It is important that good facial recognition is achieved, particularly in the external environment. Sufficient lighting also needs to be provided for CCTV cameras, so that staff can effectively monitor any activity taking place after dark.
Visual adaptation – light adaptation enables the visual system to operate throughout the enormous range of luminances that occur in nature. There are many fast-moving transition spaces for both passengers and vehicles in transport buildings where visual acuity and hazard recognition are important. Both light and dark adaptation need to be considered by the lighting designer.
Once safe levels of task lighting have been provided, the lighting design should aim to create adaptation paths for the users. Lighting must be set at appropriate levels to allow the visual system to make a progressive transition from high to low-luminance situations, and vice versa.
Any station will have several public areas where passengers’ needs and requirements are different, and so designers should adopt differing approaches when lighting these spaces.
For concourses, the use of natural light should be maximised and electric light integrated with the architectural design. Care should be taken to avoid glare and intense reflections from interior surfaces. Levels of illuminance should be consistent in all areas occupied by passengers, both by day and night. There should be no extreme variations in illuminance level, and no areas should be excessively bright or dark. There should also be no areas of strong shadow.
Entrances, exits and ticket gates should be highlighted to facilitate safe movement. Departure and arrival boards should be clear and legible and care should be taken to avoid veiling reflections on information displays and signage. Important elements such as ticket machines, ticket offices, information desks and changes in level should be emphasised.
In large interior volumes, exaggerated devices such as large-scale signage elements will help passengers to quickly navigate their way through the space.
Counters and information desks
These may broadly be divided into two categories – Open, if there is a counter top but no dividing screen between the customer and staff sides, and Protected, where a clear screen, often ballistic glass, divides staff and public.
The task lighting considerations for the two typologies vary, although the requirements are essentially the same. Good vertical illuminance is required each side of the counter to enable people to see each other’s faces. A horizontal illuminance of 400lux on each side of the counter top is a good target and this should be glare-free. Lamps should be shielded and the luminaires should also have good optical shielding.
For open counters, it may be possible to use a single lighting system to light both sides of the counter.
For protected counters, separate lighting elements will be needed to ensure that the staff and customers both have clear views of each other without the creation of veiling luminance on the glass partition. Because of the aural distortion created by these screens, and the audio systems associated with them, good visual cues are essential for successful communication and the creation of an appropriate lighting solution is paramount.
Display screen use on the staff side of protected counters should be considered. This will almost certainly require the provision of local lighting controls.
In all cases, task lighting, which enables clear and rapid identification of coin, bank notes, credit cards and printed material, should be provided.
Escalators and moving walkways
The most critical points are the landings and stepping on/off positions at the newel end of the escalator. An average maintained illuminance of 100lux should be provided horizontally on the steps with higher values provided in the area immediately around the landings to enhance passenger safety.
Integral balustrade lighting is a good way of delivering the light to the task plane but it must be designed so that the lighting does not create excessively high luminance contrasts in the step cavity.
It is worth noting that although escalators are designed for standing, people may also be walking up or down.
Boarding and alighting points
These are typically encountered at railway platform edges, and the task plane is the threshold between the vehicle and the platform, which must be clearly defined. A maintained average horizontal illuminance of 100lux is suggested at these transition points, although a lower value may be appropriate where there is a clear luminance contrast such as a white painted platform edge.
When designing for railway installations, a fundamental consideration is the passenger/train interface (PTI), since moving trains present the greatest risk to passengers and staff in a station environment.
At an open platform edge, the PTI is a location where there is a significant risk of passengers falling onto the track and into the path of an oncoming train.
In stations where the platform edge is enclosed by a screen this risk is eliminated, but appropriate lighting at the transition point between the train carriage and the platform will need to be provided.
The contrast between lighting within the vehicle and its immediate surroundings should be addressed in the lighting design to avoid problems of visual adaptation for boarding or alighting passengers.
Platform layouts will vary considerably depending on the station environment but can be considered as two principal typologies – ‘open’ (uncovered) platforms, with some freestanding structures and enclosures, or ‘enclosed’, where most of the platform space is covered by a canopy.
It is essential to provide good levels of illuminance and uniformity across the entire platform area, particularly the platform edge. For this reason, the task area of an open platform should be considered to extend up to 0.5 metres trackside. This is to ensure that adequate levels of illuminance are achieved for passengers boarding and alighting from trains.
The platform lighting should not cause glare within the field of view of approaching train drivers. The avoidance of glare and stroboscopic lighting effects is essential. Ideally, light sources should not be visible, and luminaires with a controlled downward light distribution should be specified.
Accessible design considerations
The UK Equality Act 2010 places a duty on transport service providers to make reasonable adjustments to remove potential barriers that passengers with disabilities may face when accessing both buildings and transportation services.
There are many degrees of disability experienced by a large percentage of transport users. In terms of visual impairment, this will vary between simple spectacle-corrected impairments to total vision loss.
Mobility impairments to be considered by designers will range from minor limb disability to those who use wheelchairs to access the facility.
Good lighting at points of hazards, for example, roadway edges and railway platform edges, will make the environment safer and easier and accessible for all passengers.
Spectacle wearers will experience veiling reflections if excessively bright light sources are positioned in the field of view, even at longer viewing distances. Glare should always be strictly controlled, whatever the type of visual impairment. Light sources, particularly high brightness LEDs, should always be shielded from view.
Visually impaired people find it difficult to see effectively where there are high rates of change of luminance in the field of view. As this can result in confused visual cues and loss of detail perception, it is vital that luminance changes should be gradual. It is equally important that there is a difference in the luminance of adjacent horizontal and vertical areas at low level, for example step treads and risers, as the visually impaired often rely on shadow cues to determine the position of boundaries and obstacles.
Visually impaired passengers suffer from a loss of contrast sensitivity. Therefore, important signage and wayfinding information should be backlit, so that a constant luminance across the surface of the sign is achieved together with optimal contrast ratios.
The lighting designer should also ensure that all visual information in the lit scene, both wayfinding and signage and environmental cues, can be easily interpreted from lower viewing positions for those who might be navigating a space in a wheelchair, rather than walking or standing.
Installation, access and maintenance
Due to the scale and complexity of most transportation projects, access and maintenance strategies become crucial for describing how each component can be constructed, accessed and maintained during both design and operational stages of the project.
Access and maintenance becomes even more challenging in underground station environments and all other sub-surface spaces. Each component of the lighting installation will require a carefully considered construction method, plus an access and maintenance strategy. A typical access and maintenance analysis will cover the following:
- Component overview with a summary of specific components, for example type, location and design life;
- Construction details which identify how each component can be installed on site and replaced (if and when required);
- Access, cleaning and maintenance procedures to be adopted throughout each component’s life expectancy.
It is good practice to design lighting installations that use modular elements for simple removal and replacement, and use long-life luminaires to minimise maintenance. Ease of access to the light source and other separate lighting equipment parts that require replacement should be provided and the necessity for overhead work minimised in high risk areas.
Specified lighting equipment should be cost effective to install and operate, as maintenance access periods in all transport buildings are restricted. Where mounting heights are over four metres, careful consideration should be given to how easily the lighting equipment can be maintained.
Cleaning is also a key part of the life cycle of the lighting installation and should be planned carefully to provide sufficient cleaning to each luminaire type whilst avoiding any damage due to inappropriate handling. The Ingress Protection (IP) rating of the luminaire should be carefully specified if strong, intrusive maintenance regimes including water splashing and/or water jets are anticipated.
All fixtures and fittings shall be designed to be durable and easy to clean and maintain over their service life, allowing for simple installation and replacement (if required) and good access to relevant switches, control gear and electrical connections.
Key considerations during the luminaire specification process should be durability, robustness and sleek design, which will minimise the risk of dirt and dust build up or damage. The luminaire manufacturer should provide simple and environmentally resilient fixing systems, with an adequate IP rating, to meet the design requirements.
In addition, the Cable Management System (CMS) strategy for the lighting installation should be designed to:
- Provide continuous access to primary CMS;
- Allow regular access panels for cables that require pull-through installation;
- Minimise the necessity for overhead work;
- Allow for the use of mobile-elevating work platforms or scaffold towers for safe access when working at height;
- Maximise low-level work;
- Allow for future installations.
Risk assessment and emergency lighting
Transportation systems, by their very nature, involve large numbers of people who are mostly unfamiliar with the surroundings and therefore high-integrity emergency lighting systems will be required. Higher minimum levels of illuminance than those set out in British Standard BS 5266-1 (BSI, 2016a) are likely to be needed in many areas. Local fire authority requirements should also be ascertained before commencing the emergency lighting design.
In all instances, transport buildings will require a Fire Risk Assessment to be carried out. This assessment should be reviewed and updated on a regular basis. Detailed advice for the preparation of Fire Risk Assessments for transport buildings in England, Wales and Northern Ireland is available in the Department for Communities and Local Government publication Fire Safety — Risk Assessment: Transport premises and facilities (DCLG, 2007).
A transport building or facility may also be or become subject to other relevant legislation, such as European Directives covering fire safety in transport premises, be it an air, land (road or rail) or sea facility. Where this is the case, additional advice should be sought from the relevant enforcing authority.
Lighting designers should carry out a thorough evaluation of the emergency lighting requirements in terms of illuminance, uniformity, number and positions of luminaires and required duration of the emergency lighting, as this will influence equipment specification.
Because of the large number of people using transport systems, it will frequently be necessary to provide emergency lighting in open and outdoor areas.
Central power supplies with slave luminaires may be more economic in larger installations, but these will offer a lower degree of integrity than self-contained battery emergency lighting. There are specific requirements for emergency lighting in sub-surface railways, as defined by the Fire Precautions (Sub-surface Railway Stations) (England) Regulations 2009 (TSO, 2009).
One aspect to be considered separately is that of standby lighting. In most transport situations, there are processes that have to continue during any evacuation and staff will need a working level of illuminance in public areas whilst safety procedures are carried out. This will require greater illuminance levels than for emergency escape lighting and for a longer duration. The exact performance requirements of standby lighting systems should be confirmed with the operators and fire authority at the design stage.
With the need for emergency and standby lighting, lighting on escalators, stairs and platforms, and the illumination of concourse areas and ticket halls, designers need to consider a lot of detail when putting a station-wide plan together. Many of these are detailed in the Society of Light and Lighting’s new guide LG15: Transport Buildings.
However, the ability for dramatic lighting to create an immediate and lasting impression mustn’t be overlooked. As Sir Nicholas Grimshaw, architect of Waterloo International station and Cornwall’s Eden Project, said in his foreword to the new guide, “Transport buildings have the power to be modern day cathedrals; grand, inspiring and memorable at any scale. They are the gateways to our cities, towns and communities and can hold centre stage in the public realm.”
This article was written by Keith Miller, a director of GIA Equation, an independent lighting design consultancy based in London that, as part of a design consortium together with Atkins, Grimshaw and Maynard, is responsible for generic sub-surface station design and the design of line-wide architectural components for the Crossrail programme.