Effects of weather conditions, light conditions, and road lighting on vehicle speed

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Table 8 Roads without road lighting

Weather condition	PSL	Darkness–twilight		Darkness–daylight		Twilight–daylight
TF no.	(km/h)	(km/h)	(%)	(km/h)	(%)	(km/h)	(%)
Clear
9010	70	−0.1	−0.2	1.0	1.4	1.1	1.6
9610	80	−0.2	−0.3	0.1	0.1	0.3	0.4
9688	80	5.3	6.6	2.6	3.3	−2.7	−3.4
9949	80	−0.4	−0.5	−3.0	−3.7	−2.6	−3.2
9403	90	−1.0	−1.1	0.3	0.4	1.3	1.4
9692	90	−1.8	−2.0	0.7	0.8	2.5	2.8
7250	110	−1.2	−1.0	−0.5	−0.4	0.7	0.6
9497	120	−1.7	−1.4	−0.9	−0.8	0.8	0.7
Mean		−0.1	0.0	0.0	0.1	0.2	0.1
Rain
9010	70	−0.4	−0.6	0.0	−0.1	0.4	0.5
9610	80	−0.2	−0.2	−0.5	−0.6	−0.3	−0.3
9688	80	4.4	5.5	1.2	1.5	−3.2	−4.0
9949	80	−2.3	−2.9	−6.1	−7.7	−3.8	−4.8
9403	90	−1.1	−1.2	−0.2	−0.3	0.9	1.0
9692	90	−2.0	−2.2	−0.2	−0.3	1.8	2.0
7250	110	−3.4	−3.1	−2.7	−2.4	0.8	0.7
9497	120	−1.0	−0.8	−1.7	−1.5	−0.8	−0.7
Mean		−0.8	−0.7	−1.3	−1.4	−0.5	−0.7
Snow
9010	70	0.6	0.9	−1.8	−2.5	−2.4	−3.4
9610	80	0.6	0.7	−2.7	−3.4	−3.3	−4.1
9688	80	8.8	11.0	1.2	1.5	−7.6	−9.4
9949	80	−1.5	−1.9	−1.6	−2.0	−0.1	−0.1
9403	90	−2.9	−3.2	−5.8	−6.4	−2.9	−3.3
9692	90	−10.0	−11.1	−5.3	−5.9	4.6	5.1
7250	110	0.7	0.6	−6.4	−5.8	−7.1	−6.4
9497	120	−9.2	−7.7	−6.6	−5.5	2.6	2.2
Mean		−1.6	−1.3	−3.6	−3.8	−2.0	−2.4

Average speed differences (km/h) and percentage average speed difference in relation to posted speed limit (%) per road stretch (TF no.) between natural light conditions (darkness, daylight, twilight) and divided by weather conditions (clear, rain, snow)
TF no. TF number (identification number for roads), see Tables 1 and 2, PSL posted speed limit. Mean values shown per weather condition group