At the risk of stating the obvious, paths are mainly used by pedestrians. This means the lighting has to meet different criteria from traffic routes or town centres. Safety always comes first so the path must be clearly delineated; any changes of level or direction must be visible and other pedestrians should be recognised easily.
It is also advisable to light the immediate surroundings. Apart from putting the path in context, people don’t feel secure if they think someone could be hiding in the darkness a few metres away.
Always think about what the path will look like by day as well as night. Mostly, it’s seen by day. You can decide whether it will look attractive or unattractive – there’s usually little difference in cost.
Maintenance is always an issue. There is no point in having long-life lamps or LEDs if the luminaires are easily vandalised.
There is plenty of guidance that sets out the required illumination levels. If it is a public footpath, look at BS 5489, 2013. As ever, there is a wealth of information from the SLL and ILP.
I have arbitrarily chosen a 2m-wide path with textured paving.
For the purposes of this Design Clinic, I have designed the lighting to achieve about 5 lx average on the path.
Invisible by day
Recessed uplights, often called pavers, are commonly used to light footpaths. They are especially good for wayfinding – indicating the edges of a path and showing the overall route. They don’t have to be very bright or powerful because the light does not illuminate the path. In fact, a high brightness source is sometimes a disadvantage because it makes it harder to see in the nearby darker areas. This doesn’t apply, of course, if the uplights also illuminate nearby shrubs and flowers.
It is good practice to install the pavers on both sides of the path. If not, when it is very dark, it can be hard to tell on which side of the paver line the path lays, especially if it curves.
The uplights are attractive by night and not obtrusive by day, but the big disadvantage of this type of lighting is that it doesn’t light people. Nor does it light the surface of the path. Obviously, there is some illumination on people as they pass close to the paver, but generally this is not a good way to light a path if you want to make it easy to identify people.
Pavers work better where people are already familiar with the space such as a residential garden.
Luminaires Ground-recessed uplight with toughened glass lens
Optical control Frosted glass
Arrangement Opposite pairs, as shown, typically spaced 3-5m apart
Average horizontal illuminance on path Zero because the light is shining upwards.
Electrical load Typically 0.5-1W per linear metre
Pros Easy to install and maintain, attractive to look at, low power consumption
Cons Neither the path, nor the people, are illuminated
Low level light
It seems that every architectural model I see of a new building development or renovated town centre uses bollards. This is strange because, in my experience, most lighting professionals involved in public realm projects try to avoid them.
But bollards look attractive. They are also more human in scale than a 5 or 6m column. Bollards suit gardens and driveways well. They light the surface of the path and show any changes of level. In a conservation area, their low height means that they are unlikely to interfere with bat routes.
However, for footpaths in the public realm, bollards are not usually a good choice. First, simple geometry means they can’t be spaced too far apart without causing dark patches. This is especially difficult for people with any kind of visual impairment. Closer spacing means higher power consumption.
Related to this is the fact that the low height of the bollard means the light is easily blocked – bollards in car parks are notorious for this.
Finally, vandalism is still prevalent in our public spaces and bollards are often targeted.
Luminaires 800mm-high bollard
Optical control Beam is projected sideways and forwards across path, no rearward light
Arrangement Single sided 10m apart
Average horizontal illuminance on path Typically 10-15 lx but note huge variation in uniformity
Electrical load Typically 2W per linear metre
Pros Looks good, especially by day
Cons Higher running costs, illumination can be patchy, easily vandalised
Columns for safety
My guess would be that most public paths are lit using columns. They enable you to use wider spacings and, hence, fewer units. However, there is a trade-off between using tall columns – and achieving wide spacings – or using more ‘human scale’ height columns. If vandalism is not a problem, 4m columns are a good compromise between economical spacing and impersonal lighting.
Columns are the best solution if you must make it easy to identify people coming towards you. They ensure good facial recognition and vertical illumination.
If the luminaire fits directly on top of the column, it is often called a ‘post-top’ unit. The light is spread all around and not just along the path. The alternative is the ‘side-entry’ type, which has a streetlighting type of distribution and directs the light sideways along the path.
In terms of illumination per metre of path, side-entry is probably the most energy efficient way of lighting. However, post-top lanterns with properly designed optics are almost as efficient and can be more attractive.
Luminaires Decorative post-top lantern on 4m column
Optical control Reflector and refractors
Arrangement Single sided, 20m apart
Average horizontal illuminance on path 7 lx
Electrical load Typically 1- 1.5W per linear metre
Pros Good uniformity, fewer lighting positions needed, energy efficient
Cons Tall columns may not be in keeping with the surroundings