Street luminance and night-time walking comfort: a new perspective for the urban lighting design

Figures & data

Figure 1. Pictures of the five streets.

Table 1. Characteristics of the five roads selected for the survey.

Road	Road length (m)	Road width (m)	Sidewalk width (m)
A	80	15.3	2.4
B	70	11.6	2
C	98	12	2.2
D	60	11.8	2.2
E	78	15	2.5

Table 2. Reflectance values of the five roads ‘materials.

Road	Element	Material	Reflectance (%)
A	Building 1	Plaster	11.7
		Marble	31.1
	Building 2	Plaster	34
		Plaster	20.3
	Building 3	Plaster	35.8
		Plaster	13
	Building 4	Plaster	33.7
		Marble	33.9
	Sidewalk	Porphyry cobbles	7.4
B	Building 1	Plaster	42.2
		Marble	42.4
	Building 2	Plaster	31.7
		Plaster	58.3
	Building 3	Marble	36.4
	Building 4	Plaster	39.3
		Plaster	41.3
	Sidewalk	Asphalt	6.2
C	Building 1	Brick	20.6
		Marble	46.2
	Building 2	Plaster	36.1
		Marble	35.7
	Sidewalk	Sanpietrini	8.8
D	Building 1	Plaster	13.4
		Brick	7.5
	Building 2	Plaster	13.7
		Marble	47.8
	Building 3	Plaster	25.7
		Plaster	19.8
	Building 4	Plaster	32.8
		Plaster	21.5
	Sidewalk	Asphalt	6.2
E	Building 1	Plaster	41.6
		Plaster	22.9
	Building 2	Plaster	23.2
		Marble	34
	Building 3	Plaster	11.2
		Marble	28.1
	Sidewalk	Asphalt	6.1

Table 3. Luminance values measured in the five roads.

Mean luminance (cd/m^2)
Road	Scene	Sidewalk	Wall	Side	Background	Centre	Face
A	0.9	0.9	1.7	0.4	0.8	0.6	1.4
B	1.6	0.6	2.4	1.2	1.4	1.2	1.7
C	1.8	1.4	2.6	1.2	1.3	1.7	1.6
D	1.2	0.9	1.5	1	1.1	0.9	1.3
E	0.6	0.5	0.9	0.4	0.4	0.4	0.8

Table 4. Illuminance values (lux) measured in the five roads.

Road	Average horizontal	Minimum horizontal	Uniformity	Cylindrical
A	18	6	0.3	10
B	27	21	0.8	7
C	30	7	0.2	10
D	33	10	0.3	10
E	11	3	0.3	5

Table 5. Questions presented in the questionnaire with relative answers.

	Question	Answers
Q1	Walking along this road was	very uncomfortable/very comfortable
Q2	To see clearly other people was	very easy/very difficult
Q3	To see far enough ahead was	very easy/very difficult
Q4*	The lighting along this road was	very dim/very high
Q5*	The lighting along this road was	Very uneven/very uniform

*Questions presented only at night.

Table 6. Variance of the linear correlation (R²) between participants’ ratings to different questions.

Questions	Q1–Q2	Q1–Q3	Q2–Q3	Q4–Q5
R^2	0.45	0.36	0.62	0.84

Table 7. Variance of the linear correlation (R²) between participants’ ratings and mean luminance levels of analysed areas.

Variance of linear correlation (R^2)
Question	Scene	Sidewalk	Wall	Side	Background	Centre	Face
Q1	0.82	0.76	0.96	0.54	0.62	0.90	0.63
Q2	0.36	–	–	–	0.65	0.17	0.61
Q3	0.37	–	–	–	0.55	–	–
Q4	0.56	0.05	0.75	0.40	0.72	0.38	0.91
Q5	0.44	0.16	0.65	0.10	0.36	0.25	0.87

Table 8. Variance of exponential correlation (R²) between participants’ ratings and mean illuminance levels (lux) of the sidewalk.

Variance of exponential correlation (R^2)
Question	Mean illuminance
Q1	0.59
Q2	0.65
Q3	0.22
Q4	0.65
Q5	0.50

Figure 2. Question Q1: participants day-night ratings of the five streets respect to the mean luminance levels of Scene, Sidewalk, Wall and Center.

Figure 3. Question Q2: participants day-night ratings of the five streets respect to the mean luminance levels of Face and Background.

Figure 4. Question Q3: participants day-night ratings of the five streets respect to the mean luminance levels of Background.

Figure 5. Question Q4: participants nighttime ratings of the five streets respect to the mean luminance levels of Wall and Face.

Figure 6. Question Q5: participants nighttime ratings of the five streets respect to the mean luminance levels of Face.