Road Lighting Design Research Articles

The effect of road pavement material on performance of street lighting

Road lighting efficiency depends not only on the use of effective lighting devices but also on the illuminated surface — road pavements. This paper focuses on studying the effects of aggregate lightness and aggregate colour on reflectance properties of different pavements types in Ukraine. The aim of paper is prove that the road surface is an important factor in optimizing energy efficiency and road lighting. Reflectance properties of pavements are very important in road lighting design and energy saving and should be considered more carefully in the design process of the road lighting.

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Sustainable Street Lighting Design Supported by Hypergraph-Based Computational Model

Street lighting systems are significant energy consumers in urban environments. The important step toward the reduction of this energy consumption and, thus, finding a balance between functional requirements and savings-related demands, was introducing LED-based light sources. There still exists, however, a margin for further savings, which is associated with well-tailored designs of road lighting installations. The critical impediment that has to be overcame beforehand is the computational complexity related to preparing such a well-suited design. To make this approach feasible, we propose using the formal graph-based model, enabling efficient heuristic computations. In this article, we demonstrate several real-life cases showing a coarse estimation of potential savings in terms of reduced CO2 emission. The presented results are expressed in kWh of saved energy, metric tones of CO2 , but also as a volume of combusted fuels, to make the assessment more tangible.

A New Approach to Street Lighting Design

ABSTRACTThis article compares two methods of roadway lighting design for situations compliant with EN 13201-2 ME/MEW series. The goal is to find out which one yields a more energy-efficient installation. The first method (further referred to as the “default” one), used by industry-standard software, assumes equally spaced luminaires (in any arrangement) and uniform width of the corresponding roadway. The second one (referred to as the “custom” one) operates on exact inventory data including spacing, road width, mounting height, and other parameters given per luminaire rather than set up globally. Both approaches are assumed to find solutions (installation setups) giving minimal energy consumption, which is accomplished, among others, by lamp dimming. The article presents the performed computations, discusses the obtained results, and analyzes the factors that might influence them. Results show that using the custom computation method and actual inventory data may bring an energy usage reduction at the level of 10% and more, compared to the default approach. Another issue critical from the practical point of view is the complexity of the solution-finding process. Although commonly known programs allow for building custom (nonuniform) scenes, the trial-and-error method of solution finding remarkably increases the design preparation time. Special heuristics embedded in the custom method allow avoiding the complexity issue and enable bulk processing, which is crucial in the case of large-scale computations made, for example, for large retrofits.

A Sensor-Less and Energy Efficient StreetLight Control System

Work in this paper is directed towards the design of a cost effective and energy efficient Street light control system. The main idea is to provide an alternative to LDR and Hardware timer based street light control systems which have reliability and efficiency related issues. Light dependent resistors are prone to signal variations due to factors such as presence of dust, humidity etc. and therefore their outputs cannot always be relied. Hardware timer based controls have no such issues but due to the improper and untimely manual changeovers of time settings of the controls, they are not quite efficient. Some recent research work has been done on controls employing LASER gates to detect traffic in vicinity which switch on the lights only when there is presence of vehicles but such types require huge infrastructure for installing Laser transmitters and receivers at a height of two feet near each street lamp post which is not feasible keeping in mind the scope of the paper.

Modifications to the CIE 115-2010 procedure for selecting lighting classes for roads

One of the crucial street lighting design steps considerably influencing electricity consumption is the selection of an appropriate lighting class. Therefore, after a detailed analysis of the current CEN and CIE selection procedures for streets and roads with motor or mixed traffic, several modifications of the CIE 115-2010 procedure are proposed. This way not only is its simplicity maintained but also the agreement between the two procedures is increased by up to 50%. The modifications are related to the weighting values corresponding to the traffic composition and ambient luminance as well as the inclusion of a value linked to the complexity of the visual field. The necessity for further investigation regarding the selection of lower lighting classes during the late night hours and the determination of appropriate luminance levels is also discussed.

Design of an Effective Illumination System for an Opencast Coal Mine

The scientific work documented in this article was carried out, as a part of the research investigation sponsored by a major coal company, to create a safe visual working environment for a mechanized opencast coal mine by designing an effective illumination system. It included an illumination survey of the existing lighting system in various working areas of the mine in which, the existing illuminance levels were found inadequate in most of the work places and hence an effective and modified design of the illumination system was necessary. The improvement measures were carried out by analysis of the problem, which leaded to the design of illumination system using DIALux software. DGMS standard for opencast mine lighting was used for both assessment and design of illumination systems. Haul road lighting design was performed as per CIE EN 13201 standard, which is internationally used for road lighting. The design model resulted in significant improvement over the existing system and all the standards were met as per the DGMS guidelines.

Dominant contrast as a metric for the lighting of pedestrians

CIE Publication 115 and ANSI/IESNA Recommended Practice 8-00 both use vertical illuminance 1.5 m above the ground as a design criterion for the lighting of pedestrians. While vertical illuminance has the advantage of being easy to calculate and measure, visibility is based primarily on target contrast. A central question related to the visibility of pedestrians is whether drivers need to see the whole pedestrian or can they infer the presence of a pedestrian by recognizing any part of the pedestrian’s shape. The objective of this work was to first explore various pedestrian contrast profiles that could exist and then to find a simplified approach to characterize pedestrian night-time visibility. The problem was addressed through theoretical analyses and computer simulations. Pedestrian contrast was found to be bipolar and dynamic. From the contrast profiles, we developed the concept of dominant contrast, which is defined as the contrast of any part of the pedestrian that provides the highest visibility. Dominant contrast was examined as a metric for street lighting design and night time visibility for (a) an unlit street with car headlights, (b) a lit street without car headlights and (c) a lit street with car headlights. Dominant contrast was found to be a viable metric for street lighting design and night time visibility studies.

Road Lighting Design from the Point of View of Mesopic Vision(<Special Issue>Efficient and Safe Lighting Based on the Spectral Sensitivity of Human Vision at Mesopic Light Levels)

In recent years, LED has become widespread in the world as light sources for outdoor lighting. Replacing existing light sources to LED, the energy consumption is greatly reduced. From CIE191 and other studies, under low light(mesopic) conditions, people can see brighter and more quickly detect objects which are illuminated by the lamp which has more shortwavelength components. However, this is the effect in peripheral vision, The most important light coming from the viewed object activates the very center of the retina known as the fovea. The rod response does not contribute to the important visual task of direct object recognition. Therefore, (1) the recommended light levels should be specified standard photopic photometric quantities and (2) the lamp which has more shortwavelength components is effective under mesopic lighting conditions for outdoor lighting such as a pedestrian in a roadway. In this paper, discuss technical challenges to mesopic vision technology into outdoor lighting.

Target visibility level and detection distance on a driving simulator

The visibility level (VL), a quality index in road lighting design, also serves to assess automotive lighting performance. Unlike illuminance levels, the VL provides a link between lighting design and driving performance. The reference performance of the VL is the detection of a small uniform target, standing on a uniform background (the road surface). Still, VL is subject to a number of caveats with regards to the driving task. We address the non-realistic nature of the reference target (a uniform square). A driving simulation experiment was conducted in a virtual night-time rural highway environment. The subjects drove along the road and came across different targets on the roadside. The detection distances were recorded and compared with the corresponding VL, showing rather good agreement.

A modified CIE mesopic table and the effectiveness of white light sources

Since practical application of the recently developed CIE mesopic system assumes the development of new measurement devices, recommendations and software for road lighting design, this paper presents a corrected photopic luminance table, which enables lighting designers to use the existing design procedures and measurement methods until all of these tasks are accomplished. It is also shown that there are numerous reasons for the practical application of the CIE mesopic system, although only photopic vision is involved in on-axis object recognition. Using the corrected photopic luminance table, an analysis is conducted regarding the potential electricity and cost savings when applying white light sources, which are more visually effective in the mesopic range.

Road Lighting Quality, Energy Efficiency, and Mesopic Design – LED Street Lighting Case Study

The topics of this paper are mesopic dimensioning, glare properties and energy efficiency of LED street lighting. Road lighting luminance measurements and threshold increment (TI) measurements are made for four different LED street lighting installations. The effect of mesopic dimensioning on energy consumption and life cycle costs of the LED installations are examined. Through the calculations and measurements, the energy efficiency and glare properties of the LED installations are analyzed. The measurement results indicate that the measured and calculated threshold increment values differ from each other due to varying calculation parameters in real installations. It also shows that energy can be saved when mesopic dimensioning is applied to street lighting design.

Exploring user-centered intelligent road lighting design: a road map and future research directions

Traditional road lighting systems are outdated and should be replaced with systems which can sense their environment, i.e., users and their consumer electronics (CE) devices, and react intelligently. Realizing such a system requires an interdisciplinary approach which analyzes the efficient system architecture and communication technology while taking into account the user needs. To understand these necessities, subjective experiments should be conducted in a practical testbed, similar to ours. In this paper, we first present the state-of-the-art solutions in the literature. Then, we describe the system architecture of our testbed deployed on a real street along with the preliminary experiments. Finally, we discuss the open challenges and research directions on designing a future intelligent road lighting system.

Photometric measurements for visibility level computations

Visibility level is a standard quality index in road lighting design. Three photometric values are needed to compute the visibility level of a target: its luminance, the luminance of its near background and the adaptation luminance. We discuss the consequences of how these parameters are set on the ability to predict the performance of a driver at target detection. An experiment was designed using a closed-road circuit. Sixteen targets were presented twice to 34 subjects. Six visibility level assessment methods were compared. The background luminance was set as the luminance at the bottom of the target, as the mean luminance around the target, or as the luminance associated with the maximum target contrast. The adaptation luminance was set either to the background luminance or to the mean luminance. The best non-linear fit between computed visibility level and target detection performance was found using the maximum contrast over the four sides of the square target, and setting the adaptation luminance to a unique estimated road luminance instead of the local background luminance. Even so, the variability of the visibility level data suggests great caution when using it as an index of road visibility.

Study on calculation model of road lighting visibility

Visibility is an evaluation index for road lighting, which comprehensively influences the vision reliability of drivers and is a key factor for road lighting safety and energy saving. This paper introduces the concept of road lighting visibility and its influencing factors. It also explains the small target visibility calculation model for road lighting design, and describes the significance of establishing urban road lighting visibility standards from a point of view of visual function and visual comfort of drivers.

The effect of the driving activity on target detection as a function of the visibility level: Implications for road lighting

The small target visibility model used in road lighting design is based on a strong simplification of the driving task. To specify the driver's visibility needs in a way consistent with state-of-the-art lighting engineering practice, a field experiment was designed in order to investigate target detection performances, comparing driver and passenger status conditions. Sixteen target visibility levels (VL) were used. In the driver status, 34 participants had to press a button as soon as they detected the target stimulus placed on the experimental lighted section. In the passenger status, the same participants had to detect the target stimulus while the experimenter drove. The results show that the passengers' performances (detection distance) were higher than the drivers' performances (p = .0014). Furthermore, the higher the VL, the higher the detection distance (p < .0001). These results lead up to modify the reference scenario in order to take into account human factor components for road lighting design.

Effects of the viewing context on target detection. Implications for road lighting design

The Small Target Visibility (STV) model is the main model used to assess the quality of road lighting installations ( IESNA, 2000). However, this model is based on a simple detection task in foveal vision using psychophysical data from laboratory conditions. The purpose of this study was to evaluate the impact of a complex background and apparent motion on target detection performance in mesopic vision, for three luminance contrasts, with reference to the STV scenario. To do so, participants were invited to detect standard square targets varying in terms of contrast presented in three Conditions: a uniform background, still images, and a video. Luminance levels were chosen in the mesopic domain relevant for road lighting at night. Images and video were chosen in relation to a driving task at night. The results showed that both the spatial context and the apparent motion had a negative impact on peripheral target detection performance: contrasts which are easy to detect in conditions close to the STV reference data may lead to poor performance if one adds context variables. These results give evidence that the STV model used for road lighting design based on laboratory data is limited, which strengthens previous results ( Mayeur et al., 2008). The results are discussed in relation to the field factor used by practitioners to compensate for the differences between the STV reference scenario (detection of a small square target on a lit road while driving) and the STV psychophysical reference data.

Rational-design process and evaluation of street-lighting design for apartment complexes

This study proposes the application of a rational-design process for street-lighting design considering the characteristics of space and the apartment complex on the basis of the recommended illumination levels for such. In this study, space syntax theory, which is used to generate a strategic-design framework based on detailed analysis of spatial configuration and represent any urban area as a matrix of connected spaces using computer simulations, is implemented in the design process. Based on previous research, which utilized the application of the space syntax theory to street-lighting design in a commercial area, this study extends such research to include street-lighting design of residential areas. In addition, this study evaluates current street-lighting designs in apartment complexes including selection of proper luminaires and relocation of existing luminaires. This study proposes further detailed improvements of the street-lighting design process.

The nocturnal visual environment: energy efficiency, comfort and visual acuity in urban illumination

Aspecto notável de diferenciação do ambiente urbano em relação aos ecossistemas naturais é a densidade das transformações energéticas, que tem na iluminação no período noturno uma forte expressão. Para permitir a identificação e avaliação de alguns dos valores envolvidos, apresenta-se um estudo de caso da iluminação externa decorativa na cidade de Curitiba, especificamente na zona exclusiva de pedestres da Rua XV de Novembro. Levantamentos mostram prejuízo visível da eficiência energética e indícios decomprometimento da comodidade visual e da funcionalidade. Diante da necessidade de se considerarem múltiplos critérios de escolha quando de uma intervenção ambiental urbana, são feitos comentários críticos ao conceito de iluminação externa decorativa em voga desde o ano de 2000 na cidade, representando uma tendência disseminada em diversos municípios brasileiros.

Application of the space syntax theory to quantitative street lighting design

A new design methodology for quantitative street lighting design planning using space syntax theory, which is used to generate a strategic design framework based on detailed analysis of spatial configuration, is described. The space syntax theory is based on the fact that any urban area can be represented as a matrix of connected spaces, and that mathematical properties of this matrix can be measured using computer simulations. This study explores the development of a strategic street lighting design methodology based on the results of the space syntax model, especially a level of pedestrian movement, which may have widespread usefulness in a schematic urban lighting design stage. As a case study, the relationship between observed pedestrian movement rate and the measured illuminance values of a particular district in Seoul, Korea is analyzed, and then a new quantitative street lighting plan is proposed.