Examination of the vehicle light intensity in terms of road traffic safety: a case study

Headlights LED Matrix

Light intensity in the area of the driver's eye (lx)

Headlights mode

Distance between 

vehicles

Automatic

Dipped-beam 

headlights

Long-distance 

headlights

10 m

1.6

1.55

50.5

20 m

0.83

0.8

37.62

30 m

0.52

0.5

25. 21

40 m

0.63

0.36

15.19

50 m

0.51

0.33

12.10

60 m

0.3

0.26

8.21

70 m

0.27

0.25

10.23

80 m

0.25

0.36

5.16

90 m

0.14

0.13

6.80

100 m

0.12

0.9

5.94

From the measured data, it is clear that the light intensity in the eyes area during the 

dipped-beam mode even during automatic mode was low and the driver subjectively did 

not feel the deterioration of the ability to recognize (detect) obstacles on the roadway. 

Another situation occurred in the case of long-range beam headlights, where the driver 

felt the deterioration of the ability to detect obstacles on the roadway already at vehicles 

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The Archives of Automotive Engineering – Archiwum Motoryzacji Vol. 81, No. 3, 2018

mutual distance of 70 meters, and at a shorter distance of vehicles, the complete loss of 

visibility ability [16,24]. 

Figure 2 provides a graphical comparison of the light intensity falling into the eyes of the 

opposite vehicle driver using LED headlights. In real traffic conditions, this would mean 

that the driver would have to stop the vehicle or travel the distance of 50 meters without 

information on the traffic situation.

Figure 2. Measured values of the light intensity in the area of the driver's eye (LED headlights).  

Source: authors

As for the second measurement, the vehicle Hyundai i 40, equipped with xenon head-

lights, was used. For this vehicle, the long-distance headlights mode is ensured by the 

H7 halogen bulb and the dipped-beam mode is ensured by the DS1 xenon discharge lamp. 

When measuring the light intensity in the eyes area, the same measurement procedure as 

in the previous case (vehicle with LED headlights) was repeated. Xenon headlights are not 

equipped with automatic mode, thus, measurement was carried out in only two modes. 

Table 2 lists the measured values.

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The Archives of Automotive Engineering – Archiwum Motoryzacji Vol. 81, No. 3, 2018

Table 2. Measured values of the light intensity falling into the driver´s eyes emitted by the 

xenon/halogen headlights. Source: authors