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Abstract
In this study, the influence of vehicle lights on other drivers in urban and peripheral urban environments is evaluated in two perspectives. Initially, the contribution of car headlights to visibility of the road and targets located on the road is analysed, with and without street lighting. It was observed that the contribution of the street lighting was adequate for satisfactory visibility of the targets and the use of car headlights did not, under all circumstances, improve the visibility of a target on the road. In a second phase, the influence of glare from vehicle headlights on the vision of a driver was studied under the same lighting conditions. This was found to have an important negative effect on a dark night, so much so that an object located on a road can be hidden from the driver’s view when the driver meets a vehicle approaching from the opposite direction.
... This negative contrast disappears and changes into a positive contrast due to the frontal light of the vehicle headlights. The effect of this transition on detection conditions has been investigated in various studies [13,25,35,[51][52][53][54][55][56][57][58][59][60][61]. ...
... Bacelar et al. [51,52] performed a study on the interaction of street lighting and automotive lighting regarding the visibility of flat detection targets. For this purpose, they positioned a flat target at a distance of 40 m in front of the vehicle on an illuminated road and determined the Visibility Level for the scenarios street lighting alone, automotive lighting alone and combination of street and automotive lighting. ...
... The results show that street lighting alone provides sufficient visibility and the addition of automotive lighting does not improve visibility. Thus, it can be concluded that street lights or low beams used alone provide better visibility than when they are used together [51]. In another study, Bacelar et al. found a correlation between the calculated Visibility Level and the subjects' assessment of object detectability. ...
The purpose of this work is to determine the influence of the low beam intensity of motor vehicle headlights on detection conditions in urban traffic. For this purpose, studies with fourteen subjects are conducted on three differently illuminated test roads, in which the low beam intensity is dimmed from off to fully on. At each dimming level, the subjects indicate whether or not they have detected the object, which is realized by a flat target and occurs at sixteen different positions in front of the vehicle. In addition, considerations of the contrast curve and the visibility level are made in order to determine the influence of switched off and fully switched on headlights. The results show that the negative contrast created by the existing street lighting creates detection conditions at least as good as full low beam intensity in almost all cases. The results further indicate that the influence of the low beam intensity increases with decreasing distance to the object and decreasing illumination levels. The results of this work show that an increase in low beam intensity initially leads to poorer detection conditions; thus, the option of reducing low beam intensity should be considered in urban traffic space.
... ( 3) is the luminance difference between the target and its background in the real condition, i.e. (4) where : target luminance : background luminance is the luminance difference needed for minimal visibility, between a target of certain angular size and its background. ...
... Car lights are more effective in illuminating vertical surfaces, whereas road lighting is targeted to the illumination of roads on horizontal or road surface directions [6]. Illuminance on the road is divided into three distinct zones based on illumination by car and road lighting: near, intermediate and distant zones [4,6]. Car headlights are dominant in the near zone (10 to 40 m from car headlights). ...
... Road lighting at the distances beyond the range of car headlights improves drivers' comfort by enhancing the detection of objects in the far zone and allowing the anticipation of road geometry at far distances. Therefore, the role of both car headlights and road lighting is essential in detecting objects on the roads at different distances [4,6]. ...
Traffic accidents are one of the leading causes of death globally. Accident rates are higher during darkness than during daylight. Some of the potential contributing factors in accidents are low visibility and impaired driving due to e.g. alcohol, drugs, distraction or fatigue. Introducing road lighting can mitigate the amount and severity of accidents that are due to low visual performance. However, at the same time, energy consumption and related costs of road lighting are the driving forces for more efficient road lighting technologies. Therefore, the transition of the road lighting to intelligent road lighting system that could tackle energy, cost, and safety challenges is inevitable.
So far, not much research can been found about the combined effect of different road light intensities and car headlights on drivers' visual performance. The aim of this dissertation is to provide such information under realistic conditions. The results can be used in the development of intelligent road lighting practices.
Several measures were executed in a stationary car with a constant distance to the targets. Drivers' visual performance was investigated under various road surface conditions (dry, wet and snowy), different road lighting levels, and presence or absence of glare. Finally, detection distance study was designed to determine whether similar results can be found in a moving car. Various methods were applied to study driver's visual performance such as contrast, Visibility Level, psycho-visual tests, and detection distance. All measures suggested similar conclusions.
The results of this study indicated that the current practice of road lighting levels for motorised traffic is not always necessary. In the presence of car headlights, with no glare from oncoming cars, headlights alone, or combined with a low lighting level, provided better visibility performance than when combined with full lighting intensity. In addition, the effect of different road lighting levels was not monotonic, because reducing road lighting shifted the contrast from positive to negative polarity or vice versa and made the contrast approach zero in some conditions. Therefore, road lighting should be lowered to a level that does not neutralize the effect of car headlights. This result supports the feasibility of reducing road lighting level under different road surface conditions.
In the presence of glare from an oncoming car, higher road lighting level provided better visibility than lower lighting levels, but the effect of different road lighting intensities on visual performance was not statistically significant.
... Car lights are more effective in illuminating vertical surfaces, whereas road lighting is targeted to the illumination of roads on horizontal or road surface directions [6]. Illuminance on the road is divided into three distinct zones based on illumination by car and road lighting: near, intermediate and distant zones [4,6]. Car headlights are dominant in the near zone (10 to 40 m from car headlights). ...
... Road lighting at the distances beyond the range of car headlights improves drivers' comfort by enhancing the detection of objects in the far zone and allowing the anticipation of road geometry at far distances. Therefore, the role of both car headlights and road lighting is essential in detecting objects on the roads at different distances [4,6]. ...
... However, vertical illumination in off situation was measured on another road with the same pavement characteristics. The vertical illumination measurements indicate similar results with previous studies by Boyce [6] and Bacelar [4]. As Fig. 4 indicates, the effect of car headlights drops distinctly at the distance of 60 m and beyond, which is known as the far zone. ...
PurposeRoad lighting illuminates road surface and surrounding areas of objects on a road, while car headlights illuminate vertical objects on a road. The goal of the study was to investigate the interaction between road lighting and car headlights at target detection distance. Method
Target detection distances under different road lighting intensities and car headlights were studied with and without glare from an oncoming car. Dimmable high-pressure sodium lamps with three lighting levels 49, 71 and 100% (3557, 5179 and 7252 lm) were used. Test drivers had to detect a small uniform standard target standing vertically on the straight road. ResultsIn the absence of glare (low beam car headlights), road lighting intensity levels of 100 and 49% provided comparable detection distances, while at 71% of road lighting intensity visibility was the lowest. The target was seen in negative or positive contrast in 100% of road lighting. In 71% of road lighting, the target was detected in positive contrast. While, in 49% of road lighting target was seen in negative contrast. There was a significant difference in detection distances under different road lighting intensities when there was no glare from the oncoming car. The significance main effect was between 49 and 71% of road lighting intensities. In addition, no significant differences in the effect of road lighting intensities could be found under glare from the oncoming car. In the presence of glare from the oncoming car, targets were always in negative contrast. Both road lighting and car headlights are associated with detection distances. Conclusion
The results of these experiments can give new insight to the development of intelligent road lighting considering the combined effect of road lighting and car headlights. The results provide useful insight to dim the lighting in order to save energy without impairing the detection of objects.
... The imaging luminance photometer was placed in the measurement car with a measuring height of 1.20 m, which is the average height of a driver's eyes (Bacelar, 2004;Ekrias et al., 2008;Mayeur et al., 2010). The luminance of the target and its background was measured with the luminance photometer. ...
... Drivers must have car headlights when driving at night, but road lighting may not be available all the time. These two light sources have been mostly studied separately, but there is some evidence that the combined effect of car headlights and road lighting reduces the visibility of targets on the road (Bacelar, 2004;Ekrias et al., 2008) which can, in turn, affect traffic safety. ...
... A prior study (Bacelar, 2004) on the combined effect of road and car headlights noted that in the absence of glare from an oncoming car, road lighting illumination is enough to satisfy the visibility of objects. The current study indicates that dimming road lighting in the presence of low-beam car headlights is feasible. ...
... In a study on the combined effect of road lighting and car headlights conducted by Bacelar [45], experiments were performed on a lit and unlit road to determine the effect of glare caused by headlights of oncoming cars on the driver's visibility. As expected, it was concluded that road lighting reduces the effect of glare from the oncoming car due to the improvement in the driver's visual adaptation. ...
... According to the STV concept, the driver should see the target (cube) at subtended angles above 7.45 min arc (1 min arc = π/(180•60) rad). Taking into account that the stopping (thinking plus braking) distance corresponding to the speed of 55 km/h (slightly higher than 50 km/h, agreed for the experiment) amounts to 33 m (assuming thinking time of 1 second) [40], [41], the edge of cubes needed for this experiment was: 33 m 7. 45 7.2 cm, 180 60 ...
The purpose of this study was to initiate broad research aimed to establish the preferred color of light of LEDs from a driver’s point of view. Two street lighting installations (one with 3000 K and the other with 4000 K LEDs) were evaluated both objectively and subjectively. The objective evaluation, realized using a CCD camera, included detection of small targets and pedestrians. A slight advantage was identified for the 3000 K lighting installation regarding both types of target. As for subjective evaluation (realized through a questionnaire), the task of the participants (drivers) was to choose the more appropriate between the two lighting installations regarding six lighting parameters, as well as the overall visibility. The 3000 K LED installation was evaluated as a better solution for most of the analyzed parameters, as well as for the overall visibility. However, only the results regarding the color of light (in favor of the 3000 K LEDs) and detection of small light-colored obstacles (in favor of 4000 K LEDs) were convincing, which was confirmed by the statistical analysis. Due to the obtained mild preference for the 3000 K LEDs and several limitations/challenges of the conducted surveys, it was concluded that additional research is needed in order to decide on the preferred color of light of LEDs from a driver’s perspective.
... Brémond [9] set up a nighttime highway environment simulation test scenarios and simulate obstacles of different sizes, such as vehicles, pedestrians, signs. Japanese scholars Ekrias et al. [10] utilized digital camera and set up the test environment with vehicle lamp lighting and road lighting. The visibility of obstacles under the environment was evaluated. ...
... The visibility of obstacles under the environment was evaluated. Bacelar [10] studied the effect of the existence of road lighting on the obstacle visibility. ...
The tunnel entrance section is where the visual environment changes abruptly and influences the driver’s judgment of the traffic situation in front. The lighting design of tunnel entrance sections currently usually takes the same brightness standards at the entrance and the entrance section. It makes drivers may not find the obstacles at a distance from the entrance, which is extremely detrimental to traffic safety. In this paper, a reasonable obstacle-recognition experiment under driving situation is designed to study the influence of visual environment (mainly the lighting environment) on visual adaptability in the entrance section of the tunnels and analyze the relationship between the visual stimulation caused by the sharp change of luminance and drivers’ recognition ability of obstacles. The analysis of the obstacle-recognition experiment results provides basis for further study on improvement of visual environment of tunnel sections, and is of great significance to improving traffic safety of tunnels.
... Light sources used along the road after dark include road lighting, vehicle lighting, illuminated road signs and traffic signals. 1 Vehicle headlights are the main source of illuminance on vertical targets from 10 m to 40 m away, while between 40 m and 60 m, road lighting (if present) and vehicle lighting make similar contributions to road illumination. 1,2 Hence, vehicle lighting is effective in helping drivers see road obstacles up to about 60 m ahead and could help prevent traffic crashes during the nighttime. [3][4][5] With the rapid development of lighting technology in the automotive industry, headlights have become an important research subject for many manufacturers. ...
This study aimed to investigate the impact of automotive headlights of different correlated colour temperatures (CCT) on the visual and non-visual performance of drivers. Forty drivers participated in the study, driving in a simulated night road for 45 min in three sessions. The LED headlights had CCTs of 3176 K, 4358 K and 6923 K, with an illuminance of 5 lx perpendicular to the participants' eyes. Heart rate variability (HRV), psychomotor vigilance task and Karolinska sleepiness scale were measured before and after driving. At the end of the trials, achromatic far and near visual acuity tests, as well as achromatic far and near contrast sensitivity tests, were conducted. The study revealed that CCT did not affect achromatic far and near visual acuity. However, CCT had an impact on achro-matic near and far contrast sensitivity, with higher CCT resulting in improved achromatic contrast sensitivity. As the CCT decreased, participants exhibited increased reaction time, made more errors, and reported higher sleepiness. The most significant physiological changes in HRV, including alterations in low frequency (LF), high frequency (HF) and LF/HF, were observed at lower CCT. The findings of this study suggest that both the visual and non-visual performance of drivers were enhanced when high CCTs were used for automotive LED headlights.
... Moreover, the research conducted by Cavallo et al. (2015) indicates that innovative headlight configurations can significantly increase the gap car drivers accept with respect to the motorcycle, and an Adaptive Front-lighting Systems (AFS) of motor vehicles (Peña-García et al., 2012b) and a dual grid based on luminance and luminous intensity (Peña-García and Liao, 2021) have been proposed to improve drivers' perception of road conditions, which further supports the notion that use of headlights can improve driving safety to a certain level. The contribution of car headlights to visibility of the road and targets located on the road is analyzed (Bacelar, 2004). Several researches have also highlighted the importance of vehicle headlights on improving visibility (Ising, 2008;Saraiji et al., 2016), and though most of the studies in this respect were not conducted in the tunnel, they still shed light on the effectiveness of use of headlights in the tunnel. ...
Most of traffic information inside the tunnel is obtained by the driver's vision, and tunnel lighting environment is one of the main visual information sources. As one of indispensable factors, intuitively and practically, vehicle headlights definitely contribute to the lighting environment during driving, however, less is known about how headlights affect the lighting distribution inside the tunnel. To fill such knowledge gap, this paper proposed a numerical-based approach to quantify the effect of headlights on lighting distribution inside the tunnel. Specifically , a lighting environment model was established which consisted of reflections from various light sources and structures in the tunnel. Based on the model, the parametric study on effect of vehicle headlights on tunnel illuminance distribution was conducted. In order to study the effect of turning on the headlights on obstacle identification in the tunnel, visibility level (VL) was introduced as an evaluation method and equivalent veiling luminance (EVL) also was employed as an indicator to calculate the luminance of the driver's field of view in the tunnel. According to the results, the headlights led to an improvement of 5.3 % in the average luminance of the side wall and 4.5 % in the average luminance of the road surface. The distribution of illumination on the road surface showed a 10 m periodical change due to the layout form. VL and EVL can be improved by more than three times when the headlights on. Moreover, lighting distribution with headlights on is affected by different factors such as material reflectivity and headlight illuminance intensity. The reflectivity of the road surface has the most significant impact on the luminance distribution with headlights on compared with other materials, and when the road reflectivity is decreased to 23.3 %, the average luminance ratio between the side wall and road surface increases by 3.33 times. The conclusions of the study can conduce to tunnel lighting design for improving lighting uniformity and reducing lighting energy consumption.
... This is due to the environ-mental conditions, which are not as strictly controllable as in the light tunnel and thus create more complex detection situations. This confirms the findings of Adrian [12,13,31], Damasky [18], Bacelar [48,49] and also Schneider [34], in which the required luminance difference increases with increasing complexity of the traffic situation; thus, the definition of a Visibility Level for such situations turns out to be useful. Nevertheless, the Visibility Level of 13.35 determined in the light tunnel ensures a reliable detection of the gray card at more than 70 percent of the object positions on the closed test site. ...
Motor vehicle headlamps are the only light sources that create visibility conditions for the driver in nighttime non-urban traffic. Therefore, a suitable design of these lighting systems is of the highest relevance to allow the driver an early detection of obstacles so that an appropriate reaction is possible. In order to provide a design basis for the headlamps, this article deals with the determination of the minimum required lighting conditions for reliable object detection. For this purpose, studies with drivers were conducted in a light tunnel on a closed test site, and the Visibility Level (VL) required for reliable object detection was considered. Gray cards with a reflectance of 4% were positioned on different positions of measurement grids, and the intensity of the low beam and high beam of a test vehicle was increased step by step until the drivers had detected the gray card. The results demonstrate that a Visibility Level of at least 13.35 is required in non-urban areas in order to reliably detect objects. In addition, the required Visibility Level depends on the eccentricity angle. Thus, the required Visibility Level reaches its maximum value in the foveal area of the field of view and decreases in a Gaussian shape in the periphery.
... Previous research has shown that an adaptation to the road lighting settings results in better visibility of objects. [3] Reducing the illumination of the road by the headlamp creates more easily detectable negative contrasts [4,5], while the additional light of the headlamp actually decreases this contrast possibly rendering the target invisible. Consequently, less light results not only in better energy efficiency, but also in greater road safety under certain conditions. ...
... For these reasons, standards and laws were issued to define specific objective requirements, generally based on the minimum values of photometric requirements that road lighting systems have to guarantee. At the same time, recommendations and research [51], [52], [61]- [70], [53], [71]- [80], [54], [81], [55]- [60] highlighted the need to consider additional benchmarks, mainly based on the subjective parameters to improve the visual performance, safety, and satisfaction of drivers, pedestrians, and residents. ...
Immersive virtual reality (IVR) represents one of the most promising technological aids in the development of a functional lighting design, especially when considering different points of view as users’ satisfaction.
Nowadays, immersive virtual reality is one of the new technologies with a wide range of applications. In particular, immersive virtual reality can play an important role in the lighting design, thanks to its ability to allow for a quick assessment between different design choices based on spaces, colors and light. However, the IVR has to guarantee a correct reproduction of light behavior from photometric and visual points of view, in order to be effectively used for lighting analysis.
The main outcomes can be related to the: i) methodology to use Unreal Engine 4.22 as a tool for lighting applications, allowing correct reproduction of artificial light distribution in the game engine by identifying and properly setting a restricted set of parameters and ii) investigated subjective and objective visual responses and participants' interaction with the virtual environment based on measurements of perceived presence.
In case after the download you are interested in the methodology and some results, you are kindly requested to provide these citations:
Scorpio, M., Laffi, R., Teimoorzadeh, A., Ciampi, G., Masullo, M., & Sibilio, S. (2022).
A calibration methodology for light sources aimed at using immersive virtual reality game engine as a tool for lighting design in buildings. Journal of Building Engineering, 48 doi:10.1016/j.jobe.2022.103998
Scorpio, M., Laffi, R., Teimoorzadeh, A., & Sibilio, S. (2021).
Immersive virtual reality as a tool for lighting design: Applications and opportunities. Paper presented at the Journal of Physics: Conference Series, , 2042(1) doi:10.1088/1742-6596/2042/1/012125
Scorpio, M., Laffi, R., Masullo, M., Ciampi, G., Rosato, A., Maffei, L., & Sibilio, S. (2020).
Virtual reality for smart urban lighting design: Review, applications and opportunities. Energies, 13(15) doi:10.3390/en13153809
... There is previous research on this topic by Bacelar, 28 Ekrias et al., 29 Gibbons et al. 30 and Bhagavathula et al. 31 found transitions between positive and negative contrasts with vanishing luminance differences between the target and background. However, they did not compare the contrasts to the threshold contrasts and neither investigated the influence of reflectance. ...
Modern high-resolution headlamp systems are capable of adjusting to different driving situations. However, the existing road lighting is not yet taken into account when setting the headlamp’s light distribution. This article investigates the influence of the automotive headlamp systems on the visibility of targets in different road lighting conditions and proposes a new lighting strategy based on these results. The luminances of square targets of different surface reflectances and at different distances ahead of the vehicle were measured in road lighting designed to meet classes varying from M3 to M6. For each combination the Visibility Level of the targets were determined, with road lighting alone and also when additionally illuminating the scene with the car headlamps. The influence of the headlamps on target visibility was found to depend on the road lighting class, the target distance and its reflectance. In some situations, additional light from the headlamp decreased the target Visibility Level and therefore the probability that a driver would detect it. Different ranges of headlamp light distribution were proposed for different road lighting classes to bring light only where it is needed.
... For example visual interactions between daytime running lamps and turn indicators [5,6], other lighting functions [7] and even the perception of vehicle speed [8], have been reported in the literature. In addition, even though the interaction of vehicle lighting and signaling with public lighting in streets and roads has still not been studied in any depth, research has shown its impact on the visual tasks of drivers [9]. ...
The requirements for automotive lighting systems, especially the light patterns ensuring driver perception, are based on criteria related to the headlamps, rather than the light perceived by drivers and road users. Consequently, important factors such as pavement reflectance, driver age, or time of night, are largely ignored. Other factors such as presence of other vehicles, vehicle speed and weather conditions are considered by the Adaptive Driving Beam (ADB) and Adaptive Front-lighting System (AFS) respectively, though with no information regarding the visual perception of drivers and other road users. Evidently, it is simpler to simulate and measure the light emitted by the lamps than the light reflected by the pavement or emitted by other vehicles. However the current technology in cameras and light sensors, communication protocols, and control of Light Emitting Diodes (LED), combined with decision-making techniques applied to large amounts of data, can open a new era in the operation of headlamps and thus ensure the visual needs of drivers in real time and under actual road conditions. The solution lies in an interaction road-sensor-headlamp, which is not based on the light emitted by headlamps, but rather on the light perceived by the drivers. This study thus proposes a dual grid based on luminance and luminous intensity, which would manage the headlamps by optimizing driver perception and the safety of all road users.
... Researchers [46][47][48][49] identified additional lighting at pedestrian crossings as one of the most effective actions to improve the safety and visibility of pedestrians. Higher illuminance levels at such crossings can lead to a dual goal: to signal to drivers the presence of crossing and pedestrians and to persuade the pedestrian to use the crossing point. ...
More and more cities are evolving into smart cities, increasing their attractiveness, energy efficiency, and users’ satisfaction. Lighting systems play an important role in the evolution process, thanks to their ability to affect city life at night along with people’s mood and behaviour. In this scenario, advanced lighting design methods such as virtual reality (VR) became essential to assess lighting systems from different points of view, especially those linked with the city users’ expectations. Initially, the review highlights a list of objective and subjective parameters to be considered for the lighting design of three main city areas/applications: roads, green areas and buildings. Besides, the state-of-art in using VR for outdoor lighting design is established. Finally, the Unreal game engine is used to analyse the ability of VR to take into account the lighting parameters, not yet investigated in current literature and to highlight the VR potential for augmenting lighting design. The results confirm the benefit of using VR in lighting design, even if further investigations are needed to establish its reliability, especially from the photometrical point of view.
... However, there is very low priority in systematic maintenance of headlamps in Tanzania, the maintenance of motor vehicle head lamps are not given thorough attention and one of its consequences is the night road accidents and discomfort glare to the road users due to poor road visibility caused by improper motor vehicle headlamps lighting intensity. The accidents lead to injuries, property damages, road bridges crashes and drivers fear to drive during the night (Bacelar, 2004;IGP, 2015;TBS, 2011, Mkilania and2016, Easel ,2016) Therefore, the researcher seeks to develop effective maintenance plan for improving motor vehicle headlamps lighting intensity in Tanzania.The main objective of this research was to develop effective maintenance plan for improving motor vehicles headlamps lighting intensity in Tanzania. ...
Engineering Maintenance Improvement for Head Lamp: Headlamps are important motor vehicle elements that must balance two conflicting goals: maximizing visibility for the driver and minimizing glare to other drivers, passengers and road users. However, the maintenance of motor vehicle headlamps is not given thorough attention causing road accidents at night and discomfort glare to road users. The main objective of this studywas to develop effective maintenance system for improving motor vehicle headlamps lighting intensity in Tanzania.Factors that affecting motor vehicle headlamps lighting intensity are assessed and maintenance actions for improving motor vehicle headlamps lighting intensity are developed. The experiment/measurement and visual observation were the tools used in the study and data were analyzed multilinear regression analysis. The results show that main seven factors contribute to poor motor vehicle headlamps lighting intensity as identified through experiment/measurement using beam setter with lux meter. Among seven factors; improper alignment of motor vehicle headlamps is the major problem as obtained from the analysis. Maintenance for proper vehicle lightning (Vehicle Maintenance Management)
... Thirdly, drivers in urban areas can commonly experience disability glare from the headlights of oncoming cars. The effect of this glare can be reduced through the use of road lighting [Bacelar 2004;Boyce 2008]. A fourth counterargument is that unlit road lighting does not generally provide safe driving conditions, especially for those who are unfamiliar with potentially adverse features of the road (that is, curves, geometry, surroundings, and intersections). ...
This article evaluates the potential of dimming road lighting in order to save energy and lower costs while avoiding any adverse effects on the visibility of drivers. An experimental study under varying road surface conditions was conducted to examine the combined effect of car headlights and different road lighting intensities on the visibility level. The luminance levels of the road surface, contrast and visibility level of the objects were measured from a stationary car under three road surface conditions: (a) dry, (b) wet, and (c) snowy conditions. The results support the feasibility of reducing road lighting intensity when car headlights are available. When within the range of car headlights, road lighting did not improve the visibility level. In the presence of car headlights, the average luminance providing a sufficient visibility level was found to be 0.19, 0.63, and 0.75 cd/m² under dry, wet, and snowy conditions, respectively. This would allow an energy savings of 317 kWh/year/luminaire, representing savings of 80% luminaire/year for light emitting diode (LED) luminaires.
... • the lighting standard compliant dynamic control of street lighting on the basis of traffic intensity detection results in substantial energy saving; • the savings depend on traffic intensity measurement parameters: the moving window size and step; • the cost of traffic intensity detection is also based on the moving window size and step; Further research focuses on the analysis of extending environmental parameters, and finding economically viable conditions for applying the dynamic street lighting control. These parameters include ambient or vehicle lights [23,24], as well as weather conditions. It needs to be pointed out that there is a feedback between vehicle lights and street or road lighting, which results in complex interactions between them [25][26][27]. ...
The deployment of dynamic street lighting, which adjusts lighting levels to fulfill particular needs, leads to energy savings. These savings contribute to the overall lighting infrastructure maintenance cost. Yet another contribution is the cost of traffic intensity data. The data is read directly from sensor systems or intelligent transportation systems (ITSs). The more frequent the readings are, the more costly they become, because of hardware capabilities, data transfer and software license costs, among others. The paper investigates a relationship between the frequency of readings, in particular the averaging window size and step, and achieved energy savings. It is based on a simulation, taking into account a representative part of a city and traffic intensity data, which span over a period of one year. While the energy consumption reduction is simulated, all data, including each luminaire power setting, induction loop locations and street characteristics, come from a representative sample of the city of Krakow, Poland. Controlling the power settings complies with the lighting standard CEN/TR 13201. Analysis of the outcomes indicates that the shorter the window size or step are, the more energy saving that is available. In particular, for the previous standard CEN/TR 13201 2004, having the window size and step at 15 min results in 26.75% of energy saving, while reducing these values to 6 min provides 27%. Savings are more profound for the current standard (CEN/TR 13201 2014), assuming a 15 min size and step results in 47.43%, while having a 6 min size and step provides 47.69%. The results can serve as a guideline for identifying the economic viability of dynamic lighting control systems. Additionally, it can be observed that the current lighting standard provides far greater potential for dynamic control then the previous standard.
... The STV approach also ignores the contribution of vehicular headlights. Several studies have highlighted the importance of car headlights on improving visibility [Bacelar 2004;Kurt and Ising 2008;Saraiji and others 2015; CONTACT Amira R. AbouElhamd amira.ragabmoh@yahoo.com UAE University, Sheik Khalifa Bin Zayed Street, Al-Ain, P.O.Box: 17172, United Arab Emirates. ...
In this article, we present a new calculation procedure that is based on contrast of obstacles along the road. We have developed a methodology to calculate the contrast of obstacles from the perspective of the driver. Obstacles of various heights relative to the ground were distributed along the lateral and longitudinal directions of the road. Using three-dimensional vector analysis, we determined the location of the target’s background as seen by the driver. The contrast values were then calculated along the length of the street for each obstacles’ height. We show how various street lighting design variables such as pole spacing, pole height, lamp lumens, and car headlights affect the values of the target contrast along the street. The findings suggest that the contrast-based approach to street lighting design has merit and could be the basis for street lighting calculation in the future.
... Some studies have focused on the combined effect of road lighting and car headlights. For instance, Bacelar's [2004] experiment indicated that road lighting alone was adequate for satisfactory visibility; however, drivers also have car headlights that they can always rely on, even when there is no road lighting. A study by Rea and others [2010] showed that car headlights are sufficient for safe driving at driving speeds of up to 50 km/h. ...
This article discusses various aspects of outdoor lighting energy efficiency by means of new light sources and smart lighting systems. We will also discuss visibility, traffic flow, safety, and environmental and economic aspects. The use of an optimum level of road lighting maximizes the contrast between the background and the object to be seen. This suggests that the combined effect of road lighting and car headlights should be taken into account. Solutions for future measurement need to include 3D modeling of the lighting environment and mesopic photometry. The life cycle environmental impacts of high-pressure sodium (HPS) and light emitting diode (LED) luminaires were found to be on a similar level, but it is expected that LED luminaires will surpass HPS luminaires in environmental friendliness across the whole life cycle in the future. The energy-saving potential is based on new energy-efficient technology, reduced burning hours with smart control, and new lighting dimensioning. The energy saving potential when replacing HPS lamps with LED luminaires is 31% with current technology and 66% with improved technology in the future. Further energy savings are achievable with reduced burning hours enabled with smart lighting. Altogether, the energy-saving potential of the future LED luminaire is 83% compared to current HPS luminaires.
... 10 The reduction in visibility was more pronounced in the absence of street lights compared to when the street was lit. 9 HID headlamps were found to produce greater discomfort glare than halogen headlamps. 11 The headlamp's spectrum was also found to have an effect on visual performance for off-axis targets that have low contrast. ...
This study examines the effect of different types of lamps on pedestrian night time visibility. Detection distance was used as a measure of visibility. The detection distance was measured in the presence and in the absence of on-coming car headlamps in an unlit street. Subsequently, the street was lit using metal halide, high-pressure sodium or LED luminaires. A pedestrian who changed his clothing colour randomly was used as a target. The results showed that the detection distance on the unlit road was 52% shorter in the presence of on coming car headlamps than when the oncoming car headlamps were off. A person wearing black clothing was harder to see and their mean detection distance was 60% less than when the observer was not dazzled by the oncoming car headlights. When the street was lit, the detection distance was doubled. The mean detection distance using LED lamps was statistically similar to that obtained using metal halide lamps, both of which were better than the detection distance obtained under high pressure sodium lighting.
... The retro-reflected light coming from our own vehicles is the most important in absence of public lighting [16]. This stimulus and that due to the interior boards of the car are present at any moment during the night driving, however it has been shown that the light coming from the control panels inside the car have no influence on melatonin inhibition [17]. ...
The effects of light on circadian rhythms have been known for a long time. It is well known that shift workers, transoceanic travellers and other people being exposed to light during their sleep hours have remarkable disorders in their biological clocks that can last just some days with few important effects or become really serious with higher incidence of serious diseases. One of the reasons for circadian clock to be altered is the melatonin inhibition, due to the exposure to intense and/or bluer lights during sleep hours. The inhibition of the secretion of this neurohormone has been proven to be an effective measure to enhance alert and avoid sleepiness. However, although this sleepiness avoidance is widely used in indoor illumination to achieve better productivities or higher concentration in mental tasks, nothing has been done in order to ensure that night time drivers will keep awake during long journeys via melatonin inhibition. In this sense, the lighting of the own vehicle could be the most reasonable candidate to avoid sleepiness on this collective with the consequent impact on safety. This work uses the theoretical models of dependence between light intensity and wavelength and melatonin inhibition to analyze the potential influence of car headlamps on sleepiness in people driving during long periods at night-time. The results of this research show that cars equipped with headlamps using xenon and halogen light sources, which are the most common with a still wide advantage on LEDs cause no melatonin inhibition on people driving during long periods at night and thus, the current automotive lighting technology cannot avoid distraction and sleepiness in drivers with this strategy. However, a new lighting pattern that theoretically would cause melatonin inhibition and hence, an enhanced road safety, is proposed. We conclude that the incorporation of headlighting systems providing this pattern would be extremely positive for road safety and one important step for the automotive industry.
... The conducted research [18][19][20] has shown a slight impact of the vehicle's headlights in the road with fi xed illumination on the visibility of obstacles located no further than approximately 70 m in front of the car. If we assume that the location of a critical object is considered with a similar distance, then it may be agreed that the vehicle's own headlights have no infl uence on the obstacle's visibility. ...
Driving a car, especially in city traffic, is a greatly complex process combining observation, recognition and psychomotoric functions. Safe, effi cient and comfortable driving requires a specifi c level of visibility of road obstacles. The diffi culty in spotting an obstacle in the road and in evaluating its effect on driving depends on such factors as lighting conditions in the road and its vicinity, presence of sources of glare, sources of distracting and attracting attention in the driver's fi eld of vision, for example, electronic outdoor advertising boards (LED billboards), the obstacle's geometric and photometric properties, observation conditions and the driver's visual performance. The research on the visibility of obstacles in the road has shown that the satisfaction of normative requirements in relation to average luminance and the general and longitudinal uniformity does not guarantee that an obstacle will be spotted. Thus, it is necessary to introduce another criterion to make it possible to evaluate the visibility of obstacles in the road. Visibility formula was described by Adrian in 1989 and applied with visibility levels in North America as quality criterion. For the purposes of designing road lighting systems, the visibility criterion is not used in European countries yet. Due to simplifi cations, other standards and requirements, it is also impossible to directly employ the visibility criterion used in United States, namely the Small Target Visibility, based to a large extent on Adrian's visibility model.
... The main reason for using vehicle headlights is to improve driving safety and the visibility conditions of the driver, other traffic users, and pedestrians [27]. Lately, several studies have investigated the relation between vehicle headlights and the visibility conditions of the driver [28][29][30][31]. ...
... These results can be evaluated visually and numerically to determine the appropriateness of design decisions and compliance with light standards. Because the light simulation and rendering applications seek to evaluate accurate lighting conditions, it is relevant to include other light sources, such as vehicle headlamps, that impact both the quality and experience of the lighting environment as well as light sources that contribute to overall light levels 1 . This is especially true in urban environments where there are higher densities of vehicles on the streets in closer proximity to pedestrians and buildings. ...
Computer simulation of nighttime lighting in urban environments can be complex due to the myriad of light sources present (e.g., street lamps, building lights, signage, and vehicle headlamps). In these areas, vehicle headlamps can make a significant contribution to the lighting environment 1,2 . This contribution may need to be incorporated into a lighting simulation to accurately calculate overall light levels and to represent how the light affects the experience and quality of the environment. Within a lighting simulation, photometric files, such as the photometric standard light data file format, are often used to simulate light sources such as street lamps and exterior building lights in nighttime environments. This paper examines the validity of using these same photometric file types for the simulation of vehicle headlamps by comparing the light distribution from actual vehicle headlamps to photometric files of these same headlamps. Light values are calculated in a simulated environment and numerically compared to light measurements taken in situ of actual headlamps. A discussion of how light distribution of a photometric file differs from light distributed by an actual headlamp assembly is included to articulate the primary differences.
... Given that some experiments (Bacelar, 2004) prove that the contribution of the street lighting can be adequate for satisfactory visibility of the targets and the use of car headlights did not, under all circumstances, improve the visibility of a target on the road, this AFS supposes that the necessary illuminance on the road is achieved by means of the public lighting. ...
Almost four years after the entry into force of Regulation ECE 123 on Adaptive Front-lighting Systems (AFS) for motor vehicles, and once the first cars bearing them start to circulate, a comparison between the original idea of AFS and their potential impact in safety and accident prevention is possible. In this work, we present the basic concepts of this new way to light roads and analyse some unforeseen consequences that might arise within the ECE regulatory framework once the presence of AFS becomes massive. This paper also pretends to be an useful guide for some countries like China, still considering the best way to definitively regulate these complex systems whose impact on road safety is expected to be huge.
... Figure 2 shows the vertical illuminances at different distances from a car contributed by road lighting and by the vehicle's headlamps. 27 It is clear that at 540 m from the vehicle, the illuminance is dominated by the headlamps and it is only beyond 60 m that road lighting becomes dominant. This suggests that in very dense traffic, road lighting has little contribution to make to visibility, while in very light traffic, road lighting may be only be significant beyond the range of low-beam headlamps. ...
This paper examines how the lighting of roads in the UK might be changed so as to preserve the benefits while minimising energy consumption. It is divided into four sections, these being changes in technology, changes in patterns of use, changes in standards and contracts and changes in the basis of design. Useful changes in technology and patterns of use are available now, but their use will raise the question as to whether or not environmental considerations can override conventional financial constraints. Changes in standards and the basis of design are much more long term. Comparisons of road lighting standards used in different countries show significant differences that deserve examination. As for the basis of design, consideration of the importance of light to fatal and personal injury accidents of different types suggests that road lighting should be concentrated where pedestrians are common, not where speeds are highest. Ultimately, considering carefully what problem road lighting is intended to solve and whether or not road lighting is the best answer is the key to minimising the energy consumption of road lighting without diminishing road safety.
The goal of this study is to determine how headlight illumination affects motorized two-wheeler vehicle visibility and safety on the road. There were 15 subjects considered in this study, each riding a different kind of two-wheeler having a range of lighting technology and ages. The subjects considered in the study were asked to rate the visibility from their vehicles, and hence, the study focused on headlight illumination for both vertical and horizontal light distributions at varied forward distances. The study revealed that age of the two-wheeler had huge bearing on the light output from the headlight which can be attributed to range of factors like exterior polycarbonate cover getting hazier due to aging and handling, decreased reflectivity, and misalignment of the light reflector/optics with respect to the light source. Further, the technology of the headlight light source had a big impact on how much light is produced; LED technology produces roughly three times as much light than halogen-based technology. In terms of lux values, angular spread, focusing distances, and nonuniform angular spread, there is a significant variation in light output measured across all 15 vehicles, pointing to either workmanship issues with the headlight assembly, the light design itself, or the effect of headlight aging or inconsistent headlight fitment into the two-wheeler. These results shed light on such variable headlight performance and the need for effective headlight technology, which can assist drivers, automakers, and policymakers in enhancing road visibility and safety for motorized two-wheeler vehicles.
Road lighting is best known to have the potential to improve night-time safety. The vast majority of research studies have shown that the installation of road lighting has favourable effects on the number and severity of road collisions. In addition, some evidence suggests that current road lighting practices are over-lighting the roadway. Therefore, the rapidly growing concerns about energy consumption and its related costs will force further changes in road lighting technology and practice. To date, there have been no studies that investigated the association between current knowledge and the road lighting guidelines. This article reviews and discusses CIE road lighting guidelines for motorised traffic. It then provides current knowledge in the area of lighting motorised roads leading to possibilities for intelligent lighting control. Finally, suggestions for considering dimming of road lighting based on recent developments in science and technology are provided. The three recommended approaches, static road lighting, semi-dynamic lighting levels, and dynamic lighting levels, could save energy without compromising traffic safety.
Road lighting is on the verge of one of the most attentive changes since its first introduction. The synergetic effect of the advancement of road lighting technology and usage pattern is going to change the concept of road lighting. By most estimates, light emitting diodes (LEDs) are the most energy efficient light sources that can be used in road lighting. Today, the energy saving potential when replacing HPS lamps with LED luminaires is one-third with current technology and two-thirds with improved technology in the future. This technological transformation has the potential of energy saving up to 83 % in comparison with HPS lamps. The energy saving is achievable with changing the pattern of use by intelligent road lighting control based on reducing burning hours. Intelligent road lighting can be based on such parameters as traffic density, ambient light, road condition and weather circumstances. It can also be more dynamic and consider the combined effect of road lighting and individual car headlights. The widespread adaptation of these emerging technologies is envisioned to lead towards more sustainable lighting. © 2018, LLC Editorial of Journal "Light Technik". All rights reserved.
A motorist’s visual performance can be assessed using a number of different performance criteria. The visibility of static objects (obstacles) and dynamic objects (other road users, including pedestrians) and the visibility of changes in the visual scene and the detection of relative movement are examples of important criteria. Detection just on the threshold of visibility is often not enough for safe driving: good supra-threshold visibility increases the chance of a motorist reacting in time. Another aspect, important for decreasing reaction time, is peripheral vision: noticing something out of the corner of the eye, “off” the line of sight, that needs attention. As will be explained in this chapter, peripheral vision is different in the mesopic vision range as compared to the photopic vision range.
In order to be able to draw conclusions as to what lighting quality is needed under different situations, the individual relationships between photometric lighting parameters and the different performance criteria, such as revealing power, total revealing power, visibility level, small target visibility and relative visual performance, have to be studied. Fortunately, there are many research results on the relationships between the most important performance criteria and the various lighting parameters. These will be dealt with here. The impact of adverse weather conditions and of the effect of vehicle lighting on the visual quality obtained from fixed road lighting, are other items dealt with here. Finally, the neurological influence that lighting could possibly have in helping to keep the motorist alert will be discussed.
This book outlines the underlying principles on which modern road lighting is based, and provides the reader with knowledge of how these principles should be applied in practice. This book offers a completely fresh approach to the subject, reflecting how the technology of road lighting has progressed to keep up with the changes in lamp technology, especially in solid state light sources, and the increasing awareness of energy use and environmental issues. The book is divided into three parts. Part One describes lighting of open roads, with chapters discussing visual performance and comfort (including the effects of mesopic vision and age), and international standards and recommendations for road lighting. Lighting equipment is introduced; specifically lamps and luminaires in terms of their practical properties and features, but also the road surface and its characteristics. A chapter on Lighting Design makes the link between theory and practice, providing the reader with the knowledge needed for effective lighting design, including aspects relating to sustainability. The final chapter of Part One deals with lighting calculation conventions and measurements. Part Two is devoted to light pollution. The negative consequences of light pollution are described and tactics to restrict light pollution explained. Lighting criteria are defined that can be used by the lighting designer to guarantee installations stay within acceptable limits. International standards and recommendations on the restriction of light pollution are discussed. Part Three is devoted to tunnel lighting, with chapters discussing visual performance in tunnel environments, lighting criteria, standards and recommendations, and concluding with a chapter on tunnel lighting equipment and design. This book is a valuable resource for road lighting designers and engineers, students of lighting design and engineering, town planners, traffic engineers, environmental specialists, and lamp and luminaire developers and manufacturers.
In this paper road lighting measurements were made to study the impacts of vehicle headlights on luminance contrasts of targets located on the road. Experimental measurements were made on a highway to investigate the contribution of halogen and high-intensity discharge headlights to road lighting. The measurement results indicate that in general, the use of vehicle headlights, in the presence of road lighting, does not improve the luminance contrasts of targets located on the road. The impacts of vehicle headlights are highly dependent on the vehicle, headlights type, target reflection factor, position of the target, position of the vehicle and road lighting installation. The effects of HID headlights on targets luminance contrasts were more significant compared to the ones of halogen headlights.
Current IESNA recommended practice refers to pedestrian illumination on roadways as a function of the minimum vertical illuminance Ev(min). In this article, a method is developed to find the location of the maximum Ev(min) along streets. Calculation grids are set on the side walk, along the streets and, along the median. It was found that while the vertical illuminance at one point along the street may be greater than 1 FC, at other points along the longitudinal and lateral axes, the vertical illuminance can be zero even on streets that meet the recommended horizontal illuminance targets.
Visual perception is the most important of the human senses. Lack of visual perception is one of the main causes of accidents. The safety of vehicle traffic depends on how well automotive lighting supports the visual perception of the driver. This book explains the fundamentals of visual perception, like e.g. physiology of eye and brain, as well as those of automotive lighting technology, like e.g. design of headlamps and signal lights. It is an interdiciplinary approach to a fastly evolving field of science and technology, answering questions like "How does information enter our brain when driving a car?" and "What are the benefits and dangers of LED signal lighting?".
In this study road lighting measurements were made to investigate the impacts of vehicle headlights on luminance contrasts of various targets located on the road. Altogether seven different studies were made to investigate the contribution of halogen and high-intensity discharge headlights to road lighting. The measurement results indicate that in general, the use of dipped vehicle headlights, in the presence of road lighting, does not improve the visibility of various targets located on the road. In fact, in most occasions when the targets were seen darker than the background, dipped headlights reduced target contrasts and in some cases they even made the target merge into the background. The impacts of vehicle headlights are highly dependent on the vehicle, headlights type, target reflection factor, position of the target, position of the vehicle and road lighting conditions. As assumed, the effects of HID headlights on targets luminance contrasts were more significant compared to the ones of halogen headlights.
This paper covers verification of the model for computing visibility levels using hemispherical targets which has been developed by J. Lecocq (Thorn Europhane). The outputs from this model have been compared with the ratings given by observers. The experiment confirmed the reliability of visibility calculations using the model. Good correlation was achieved between the levels of visibility and the rating given by observers. The spread of the ratings was also fairly constant for all the observations. The results from the experiment with hemispherical targets were compared with those obtained with flat targets. The study demonstrated that it is possible to use either of these visibility level calculation models.
This study measured direct and rearview-mirror glare illuminances produced by low-beam headlamps in a sample of 22 passenger vehicles. The glare illuminances were measured for 12 common glare situations that were defined by a full factorial combination of three scenarios (oncoming driver, center rearview mirror of a preceding driver, or driver-side mirror of a preceding driver one lane to the right), two longitudinal distances (25 m or 50 m), and two vertical locations (illuminated vehicle being either a car or a light truck/van/sport utility vehicle). The measurements were made outdoors at night on asphalt pavement. The median illuminances (not taking into account window transmittance or mirror reflectance) ranged from 0.5 lux for an oncoming driver of a light truck/van/sport utility vehicle at a distance of 50 m, to 3.4 lux at the driver-side mirror of a preceding car at 25 m one lane to the right. The ratios of the maxima and the minima measured for each of the 12 glare situations were large, ranging from about 5:1 to 36:1. The median actual illuminances were compared to the median expected illuminances based on a recent, laboratory-measured, representative sample of US low-beam patterns, taking into account the possible effects of dirt, voltage, misaim, and pavement reflectance. This analysis indicates that the actual illuminances could be very well modeled using the laboratory-measured beam patterns and assuming a linear relationship between the light output of clean and dirty headlamps. Additional analyses evaluated the relationships between headlamp mounting height and glare illuminance.
The introduction of the visibility level as a criterion for the obtainable visual information necessitates a metric to allow its quantification. On the basis of Adrian's, Aulhorn's and Blackwell's data a method has been developed to compute the luminance difference thresholds ΔL of visual targets of variable size and positive and negative contrast. Another parameter relevant to ΔL is the observation time to cope with practical viewing conditions in which fixation was found to be restricted to 0.1 to 0.2 s. The effect of age on the threshold contrast and that of disability glare has been incorporated. The numerical description allows the determination of the visibility level VL of objects in the visual field. A practical example of how to obtain VL is presented.
This study compared the quantitative influence of a variety of factors on the performance of low-beam headlamps. The factors included were vertical aim, horizontal aim, mounting height, lateral separation, lens dirt, lamp voltage, number of functioning lamps, vehicle type, beam pattern and light source. The following aspects of headlamp performance were considered: visibility of pedestrians, visibility of road delineation, visibility of vehicle reflex reflectors, visibility of rettoreflective traffic signs, visibility of targets near the road expansion point, glare directed towards oncoming drivers, glare reflected from wet pavement towards oncoming drivers, glare directed towards rearview mirrors of preceding vehicles, and foreground illumination. A sales-weighted average US beam pattern, with lamps mounted at sales-weighted average locations, formed the basis for most of the analyses. The results indicate that, from among the factors studied, vertical aim is overwhelmingly the most important factor in influencing the performance of low-beam headlamps. The second most important factor is the number of functioning lamps. The main implication of this study is that major improvements in current (fixed as opposed to adaptive) low-beam headlighting could be achieved primarily by better control of vertical aim and by use of longer-life headlamps. Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/68939/2/10.1177_096032719903100403.pdf
This study evaluated changes in the light output of rear signal lamps as a function of dirt accumulated during a 482 km drive, representing ten days' driving for a typical United States driver. The complete route was traversed on three separate occasions, under each of the following environmental conditions: dry, wet, and snowy/salty. Luminous intensity measurements were obtained for all US and European test points. Photometry for each of two stop lamps was performed twice after the completion of each drive: first 'as is' and then after cleaning. The results indicate that dirt deposits tended to cause the light output to decrease at the points tested. The reductions after the dry drive were all less than 8%. However, after the wet and snowy/salty drives reductions of more than 25% occurred at several test points, with a maximum reduction of 37%. The test percentage reductions occurred for the points at and near the optical axes of the lamps, which had the highest original intensities, and at which maintaining adequate intensity is presumably most important. A theoretical analysis of the changes caused by dirt indicates that this is the pattern of results that wild usually occur. A full evaluation of the significance of the effects of dirt that are quantified in this paper should be done in the context of other factors that affect signal-lamp intensity, such as vehicle voltage control and lamp design. It may also be important to measure more fully the range and distributions of dirt conditions in the real world. However, the present results demonstrate that, within the range of common weather conditions, dirt can cause reductions of signal-lamp intensity that are large enough to be of concern, especially for the relatively important positions at and near the optical axes of signal lamps. Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/68399/2/10.1177_096032719803000104.pdf
Etude d’un modèle de visibilité pour le calcul des installations d’éclairage public
- A Bacelar
- J Lecocq
- J Cariou
- M Hamard
Recommandations relatives a` l’éclairage des voies publiques
- Afe