For the past few years Steve Fotios has focussed on lighting for pedestrians – how can we use lighting to enhance the safety and perceived safety of pedestrians? There are two reasons for doing this. One, because current standards are not qualified by robust empirical data, so we do not know that they are optimal; Two, because better lighting promotes more walking. Both reasons promote the sustainability of lighting. Talk by Steve Fotios CEng MEI MSLL MILE PhD BEng(Hons) FHEA PGCE, Sheffield University

1. Lighting for Pedestrians:
• Design metrics
• Picking a class
• Light level
Steve Fotios
Professor of Lighting and Visual Perception
University of Sheffield

2. Road lighting standards: What was
specified?
British Standard Specification 307:1927
• Minimum illuminance at a point midway between two lamp
posts
1930s to BS5489-3:1977
• Spacing (according to road width) and minimum luminous flux
BS5489-3:1989 to BS5489-3:2013
• Average and minimum illuminances

3. CIE115: 2010
Currently, CIE-115:2010 uses average and minimum horizontal
illuminance, colour rendering, and possibly vertical and semi-
cylindrical illuminances to characterise lighting.
These need to be questioned.
One reason to do so is that the evidence for the recommended
criteria levels and the means for determining a light class are
unknown.

4. Changes in Lighting Practice
20th Century
• LPS / HPS lamps
• Broad spatial distribution
• Little choice in spectrum
• Little concern over energy or sky glow
Little need to consider
design metrics – we
can’t do much and no
pressure to do so.
Technical opportunities -
it is possible to vary
more design parameters
Political / environmental
demands – we should
consider design metrics
21st Century
• LED arrays / metal halide lamps
• Smaller size, better optical control
• Spectral tuning possible
• CIE mesopic system – S/P ratio matters
• Great concern over sky glow and energy
use

5. How much light?
Illuminance is more convenient than
luminance:
• Do not need to define surface of view and its
reflectance
• Pedestrians have more widely scattered
pattern of fixations than do drivers

6. Where is it measured?
Surface Associated with Comment
Horizontal Trip hazard detection
and reassurance
• Simplest: do not need to define
orientation
Vertical Evaluating other
people and
reassurance?
• Orientation to be defined
Semi-cylindrical ? • Non-standard meter
• Orientation to be defined
• Would need two values to improve over
vertical illuminance
• No proven benefit over other measures
Hemi-spherical ? • Non-standard meter
• Do not need to define orientation
• No proven benefit over other measures

7. Pedestrian Reassurance
These graphs show the result of a field study of reassurance – how
safe do you feel when walking. A smaller day-dark difference (the y-
axis) indicates lighting that is better at enhancing reassurance.
These data suggest that uniformity is a better measure of
reassurance than is average horizontal illuminance.
Fotios S, Liachenko Monteiro A, Uttley J. Evaluation of pedestrian reassurance gained by higher illuminances in
residential streets using the day-dark approach. Lighting Research and Technology, 2019; 51(4): 557-575.

8. Uniformity
Uniformity = Eminimum / Eaverage
Emax
Emin
+ + + + + + + + + +
Eaverage
Illuminance(lux)
This standard measure of uniformity is incomplete – it
says nothing about the rate of change between dark and
bright sections. A new measure of uniformity is needed
+ + + + + + + + + +
+ + + + + + + + + +

9. Lamp spectrum
Common metrics include CCT, CRI, S/P ratio
• Higher S/P ratio can enhance peripheral detection and spatial
brightness
• CIE115:2010 “high colour rendering contributes to a better
facial recognition”.
• This is not supported by credible empirical evidence.
• BS5489-1 2003: Ra>60 (i.e. “don’t use LPS/HPS lamps.”)
• CCT ….. ?
• Not a good predictor of brightness (Fotios & Cheal 2011) or
pleasantness (Fotios 2017)

10. Proposal: P-class design targets
Minimum horizontal
illuminance
Pavement hazard
detection
Uniformity of horizontal
illuminance
Vertical illuminance
S/P ratio
Reassurance
Evaluate other people
Hazard detection and
reassurance/spatial
brightness

11. CIE115: 2010 – Road Lighting for Pedestrians
Current metrics

12. CIE115: 2010 – Road Lighting for Pedestrians
Proposed metrics

13. PICKING A CLASS OF LIGHTING

14. Which class of lighting is appropriate?
Description of typical
application
Points-based
system
The process of picking a lighting class has changed, from a
context narrative to a system of weighting points. While the latter
gives the illusion of precision, there are many questions.

15. Picking a lighting class
Parameter Options Weighting Value
Speed
Low 1
Very low (walking speed) 0
Traffic volume
Very high 1
High 0.5
Moderate 0
Low -0.5
Very low -1
Traffic
composition
Pedestrians, cyclists and
motorized traffic
2
Pedestrians and
motorized traffic
1
Pedestrians and cyclists
only
1
Pedestrians only 0
Cyclists only 0
Parked
vehicles
Present 0.5
Not present 0
Ambient
luminance
High 1
Moderate 0
Low -1
Facial
recognition
Necessary Additional requirements
Not necessary No additional requirements
CIE 115: 2010

16. Picking a lighting class
Parameter Options Weighting Value
Speed
Low 1
Very low (walking speed) 0
Traffic volume
Very high 1
High 0.5
Moderate 0
Low -0.5
Very low -1
Traffic
composition
Pedestrians, cyclists and
motorized traffic
2
Pedestrians and
motorized traffic
1
Pedestrians and cyclists
only
1
Pedestrians only 0
Cyclists only 0
Parked
vehicles
Present 0.5
Not present 0
Ambient
luminance
High 1
Moderate 0
Low -1
Facial
recognition
Necessary Additional requirements
Not necessary No additional requirements
CIE 115: 2010
Why these
parameters? …. They do not match the intended
purpose of road lighting
(CIE115:2010)
“enable pedestrians to discern
obstacles or other hazards in their
path and be aware of the
movements of other pedestrians,
friendly or otherwise, who may be
in close proximity”

17. Picking a lighting class
Parameter Options Weighting Value
Speed
Low 1
Very low (walking speed) 0
Traffic volume
Very high 1
High 0.5
Moderate 0
Low -0.5
Very low -1
Traffic
composition
Pedestrians, cyclists and
motorized traffic
2
Pedestrians and
motorized traffic
1
Pedestrians and cyclists
only
1
Pedestrians only 0
Cyclists only 0
Parked
vehicles
Present 0.5
Not present 0
Ambient
luminance
High 1
Moderate 0
Low -1
Facial
recognition
Necessary Additional requirements
Not necessary No additional requirements
CIE 115: 2010
Why these
parameters?
Why these options?
And how are they
defined?

18. Picking a lighting class
Parameter Options Weighting Value
Speed
Low 1
Very low (walking speed) 0
Traffic volume
Very high 1
High 0.5
Moderate 0
Low -0.5
Very low -1
Traffic
composition
Pedestrians, cyclists and
motorized traffic
2
Pedestrians and
motorized traffic
1
Pedestrians and cyclists
only
1
Pedestrians only 0
Cyclists only 0
Parked
vehicles
Present 0.5
Not present 0
Ambient
luminance
High 1
Moderate 0
Low -1
Facial
recognition
Necessary Additional requirements
Not necessary No additional requirements
CIE 115: 2010
Why these
parameters?
Why these options?
And how are they
defined?
Is a weighting of
1.0 correct
Is the cumulative
assumption
correct?
Why facial
recognition and when
is it not necessary?

19. BS5489-1:2013
Currently there are two Tables, defining lighting class by speed,
traffic flow, and ambient ligt level. This is much simpler than the
CIE-115:2010 and EN 13201-2:2015 systems.
But there is some unnecessary duplication.

20. BS5489-1:2013
These three pairs of columns lead to the same lighting classes, so
there is no need to discriminate by ambient light level.

21. BS5489-1:2013
Traffic flow Slow vehicles,
cyclists and
pedestrians
v≤30 mph v≤30 mph
E1 – E4 E1 or E2 E3 or E4
Busy P4 P3 P2
Normal P5 P4 P3
Quiet P6 P5 P4
A simplified version of Tables A5 and A6,
…. showing the P classes

22. BS5489-1:2013
Traffic flow Slow vehicles,
cyclists and
pedestrians
v≤30 mph v≤30 mph
E1 – E4 E1 or E2 E3 or E4
Busy 5.0 lux 7.5 lux 10 lux
Normal 3.0 lux 5.0 lux 7.5 lux
Quiet 2.0 lux 3.0 lux 5.0 lux
A simplified version of Tables A5 and A6,
…. or the average illuminance recommended for each class

23. BS5489-1:2013
Traffic flow Slow vehicles,
cyclists and
pedestrians
v≤30 mph v≤30 mph
E1 – E4 E1 or E2 E3 or E4
Busy 5.0 lux 7.5 lux 10 lux
Normal 3.0 lux 5.0 lux 7.5 lux
Quiet 2.0 lux 3.0 lux 5.0 lux
The benchmark of the current light levels was use of low/high
pressure sodium lamps – see section B.5.5 of PLG03. BS5489-
1:2013 shows that lower light levels can be used when using
lamps of higher S/P ratio and CRI than sodium lamps (Table A7).

24. BS5489-1:2013
Now that white light is the first choice of lamp, the P-class
illuminances should be reduced … and PLG03 be used to
increase light levels when using sodium lamps (or other sources
of low S/P ratio and low CRI).
Traffic flow Slow vehicles,
cyclists and
pedestrians
v≤30 mph v≤30 mph
E1 – E4 E1 or E2 E3 or E4
Busy 3.0 lux 5.0 lux 7.5 lux
Normal 2.0 lux 3.0 lux 5.0 lux
Quiet 2.0 lux 2.0 lux 3.0 lux

25. BS5489-1:2013
This range of light levels is supported by research evidence
Traffic flow Slow vehicles,
cyclists and
pedestrians
v≤30 mph v≤30 mph
E1 – E4 E1 or E2 E3 or E4
Busy 3.0 lux 5.0 lux 7.5 lux
Normal 2.0 lux 3.0 lux 5.0 lux
Quiet 2.0 lux 2.0 lux 3.0 lux
Fotios S. Subsidiary road lighting. P-
class lighting; what illuminance and
why? Lighting Journal. 2019; 84(1)
January: 6-9
TC 4-52:
Lighting for
pedestrians

26. Summary
Regarding P-class recommendations in CIE-115:2010
and EN 13201-2:2015
• The basis is unknown.
• The method of picking a light level does not match
the stated purpose of lighting.
• There was no evidence for the light levels. Recent
research suggests the higher illuminances (P1, P2)
are not necessary.
Looking ahead - it may be beneficial to change the
design metrics, specifically;
average and minimum
horizontal illuminance
minimum horizontal
illuminance and uniformity
X

27. Professor Steve Fotios
School of Architecture,
University of Sheffield, UK
steve.fotios@sheffield.ac.uk
10/11 November 2020
Eindhoven
BRIGHT
LIGHTS