Gaps and Emerging Technologies in the Application of Solid-State Roadway Lighting
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Expansion of anthropogenic noise and night lighting across our planet1,2 is of increasing conservation concern3–6. Despite growing knowledge of physiological and behavioural responses to these stimuli from single-species and local-scale studies, whether these pollutants affect fitness is less clear, as is how and why species vary in their sensitivity to these anthropic stressors. Here we leverage a large citizen science dataset paired with high-resolution noise and light data from across the contiguous United States to assess how these stimuli affect reproductive success in 142 bird species. We find responses to both sensory pollutants linked to the functional traits and habitat affiliations of species. For example, overall nest success was negatively correlated with noise among birds in closed environments. Species-specific changes in reproductive timing and hatching success in response to noise exposure were explained by vocalization frequency, nesting location and diet. Additionally, increased light-gathering ability of species’ eyes was associated with stronger advancements in reproductive timing in response to light exposure, potentially creating phenological mismatches⁷. Unexpectedly, better light-gathering ability was linked to reduced clutch failure and increased overall nest success in response to light exposure, raising important questions about how responses to sensory pollutants counteract or exacerbate responses to other aspects of global change, such as climate warming. These findings demonstrate that anthropogenic noise and light can substantially affect breeding bird phenology and fitness, and underscore the need to consider sensory pollutants alongside traditional dimensions of the environment that typically inform biodiversity conservation.
Light pollution is increasing and artificial light sources have great impacts on animals. For migrating birds, collisions caused by artificial light pollution are a significant source of mortality. Laboratory studies have demonstrated that birds have different visual sensitivities to different colors of light, but few field experiments have compared birds’ responses to light of different wavelengths. We used 3 monochromatic lights (red, green, and blue) and polychromatic yellow light to study the impact of wavelength on phototaxis at 2 gathering sites of nocturnally migrating birds in Southwest China. For both sites, short-wavelength blue light caused the strongest phototactic response. In contrast, birds were rarely attracted to long-wavelength red light. The attractive effect of blue light was greatest during nights with fog and headwinds. As rapid urbanization and industrialization cause an increase in artificial light, we suggest that switching to longer wavelength lights is a convenient and economically effective way to reduce bird collisions.
New technological developments modulate the light levels of LED street luminaires according to traffic volumes: light levels are increased given traffic and reduced in its absence. Such dimming of street lights reduces the level of artificial light at night (ALAN) and may thus contribute to mitigate light pollution. To quantify the impact of traffic-driven dimming of street lights on nocturnal insect abundance and bat activity in comparison to full light (i.e., dimming functions of luminaires switched off), we mounted 20 insect flight-interception traps and ten batloggers on street light poles along two dimmable street light sections. Insect abundance and bat activity were measured alternately with one week of full street lighting followed by a week with light levels modulated by traffic volumes. In total, 16 dimmed and 16 full-light days were investigated. Overall, traffic-driven dimming reduced light levels by 35%. Weather conditions (warm, dry nights) were the main drivers of insect abundance and bat activity, but traffic-driven dimming resulted in lower numbers of insects caught and reduced bat activity. Among insect groups, Heteroptera benefited most from dimming. For bats, urban exploiters (Pipistrellus spp.) benefited from increased availability of prey at brightly lit street lights, while less frequent species (Myotis spp.) did not benefit from street lighting. We conclude that street light dimming technology may contribute to mitigate negative effects of ALAN on nocturnal organisms, although the measure may not be efficient enough to support light-sensitive and threatened species.
Drosophila melanogaster has long been a popular model insect species, due in large part to the availability of genetic tools and is fast becoming the model for insect colour vision. Key to understanding colour reception in Drosophila is in-depth knowledge of spectral inputs and downstream neural processing. While recent studies have sparked renewed interest in colour processing in Drosophila, photoreceptor spectral sensitivity measurements have yet to be carried out in vivo. We have fully characterised the spectral input to the motion and colour vision pathways, and directly measured the effects of spectral modulating factors, screening pigment density and carotenoid-based ocular pigments. All receptor sensitivities had significant shifts in spectral sensitivity compared to previous measurements. Notably, the spectral range of the Rh6 visual pigment is substantially broadened and its peak sensitivity is shifted by 92 nm from 508 to 600 nm. We propose that this deviation can be explained by transmission of long wavelengths through the red screening pigment and by the presence of the blue-absorbing filter in the R7y receptors. Further, we tested direct interactions between photoreceptors and found evidence of interactions between inner and outer receptors, in agreement with previous findings of cross-modulation between receptor outputs in the lamina.
Artificial light at night (ALAN) is increasing exponentially worldwide, accelerated by the transition to new efficient lighting technologies. However, ALAN and resulting light pollution can cause unintended physiological consequences. In vertebrates, production of melatonin-the "hormone of darkness" and a key player in circadian regulation-can be suppressed by ALAN. In this paper, we provide an overview of research on melatonin and ALAN in vertebrates. We discuss how ALAN disrupts natural photic environments, its effect on melatonin and circadian rhythms, and different photoreceptor systems across vertebrate taxa. We then present the results of a systematic review in which we identified studies on melatonin under typical light-polluted conditions in fishes, amphibians, reptiles, birds, and mammals, including humans. Melatonin is suppressed by extremely low light intensities in many vertebrates, ranging from 0.01-0.03 lx for fishes and rodents to 6 lx for sensitive humans. Even lower, wavelength-dependent intensities are implied by some studies and require rigorous testing in ecological contexts. In many studies, melatonin suppression occurs at the minimum light levels tested, and, in better-studied groups, melatonin suppression is reported to occur at lower light levels. We identify major research gaps and conclude that, for most groups, crucial information is lacking. No studies were identified for amphibians and reptiles and long-term impacts of low-level ALAN exposure are unknown. Given the high sensitivity of vertebrate melatonin production to ALAN and the paucity of available information, it is crucial to research impacts of ALAN further in order to inform effective mitigation strategies for human health and the wellbeing and fitness of vertebrates in natural ecosystems.
Understanding the ecological traits which predispose species to local or global extinction allows for more effective pre-emptive conservation management interventions. Insect population declines are a major facet of the global biodiversity crisis, yet even in Europe they remain poorly understood. Here we identify traits linked to population trends in ‘common and widespread’ UK moths. Population trend data from the Rothamsted Research Insect Survey spanning 40 years was subject to classification and regression models to identify common traits among species experiencing a significant change in occurrence. Our final model had an accuracy of 76% and managed to predict declining species on 90% of occasions, but was less successful with increasing species. By far the most powerful predictor associated for declines was moth wingspan with large species declining more frequently. Preference for woody or herbaceous larval food sources, nocturnal photoperiod activity, and richness of habitats occupied also proved to be significantly associated with decline. Our results suggest that ecological traits can be reliably used to predict declines in moths, and that this model could be used for Data Deficient species, of which there are many.
Objective: Nighttime crashes are overrepresented on the U.S. highway system. Roadway lighting, which provides additional visibility by supplementing vehicle headlights, has been identified as an effective countermeasure to improve nighttime safety. However, the existing literature does not provide a thorough understanding of the effects of street lighting photometric characteristics on nighttime crash occurrence on roadway segments. This study aimed to investigate the relationship between lighting photometric measures and nighttime crash risk on roadway segments and develop a crash modification function/factor (CMF).
Methods: The research team collected horizontal illuminance data on 440 roadway segments between 2 successive signalized intersections in Florida for 2012–2014 and matched 4 years of nighttime and daylight crash data (2011–2014). Random parameter negative binomial models were estimated for both nighttime and daylight crash frequencies. The expected night-to-day crash odds ratio, as an equivalent of CMF, was derived from the fitted models with the correction of estimation variances. The confidence intervals (CIs) of the developed CMF were estimated using the Cox method.
Results: The coefficient of the mean of horizontal illuminance is significantly negative in the nighttime model. The coefficients of the standard deviation of horizontal illuminance are significantly positive and normally distributed in both the nighttime and daylight models. The significance of the standard deviation in the daylight model captures the confounding effects—a high standard deviation correlates with high traffic exposures, poor safety design standards, and low maintenance quality. The CMF based on the expected daylight-to-day odds ratio was developed as an exponential function of the increments and the increment squares of the mean and the standard deviation of horizontal illuminance. Its 95% CIs indicate that the CMF is almost significant over the whole range. Other significant variables contributing to nighttime crash risk include annual average daily traffic, truck percentage, segment length, access density, undivided roads, and urban/city limits.
Conclusions: Horizontal illuminance characteristics have a significant impact on nighttime crash risk on roadway segments. An increase in the mean of horizontal illuminance, indicating an improvement in average lighting level, tends to decrease nighttime crash risk; an increase in the standard deviation, representing a poor uniformity of lighting pattern on a roadway segment, is more likely to raise nighttime crash risk. Because the 2 measures are strongly correlated in a low mean range (<0.44 fc), the 2 photometric measures need to be considered together to interpret the safety effects of lighting patterns. The standard deviation shows better performance in measuring lighting uniformity on a roadway segment than the traditional ratios (max-to-min and mean-to-min). However, a new photometric measure is needed to capture the true lighting pattern influencing driver vision at night.
A growing number of offshore wind farms have led to a tremendous increase in artificial lighting in the marine environment. This study disentangles the connection of light characteristics, which potentially influence the reaction of nocturnally migrating passerines to artificial illumination under different cloud cover conditions. In a spotlight experiment on a North Sea island, birds were exposed to combinations of light colour (red, yellow, green, blue, white), intensity (half, full) and blinking mode (intermittent, continuous) while measuring their number close to the light source with thermal imaging cameras.
We found that no light variant was constantly avoided by nocturnally migrating passerines crossing the sea. The number of birds did neither differ between observation periods with blinking light of different colours nor compared to darkness. While intensity did not influence the number attracted, birds were drawn more towards continuous than towards blinking illumination, when stars were not visible. Red continuous light was the only exception that did not differ from the blinking counterpart. Continuous green, blue and white light attracted significantly more birds than continuous red light in overcast situations.
Our results suggest that light sources offshore should be restricted to a minimum, but if lighting is needed, blinking light is to be preferred over continuous light, and if continuous light is required, red light should be applied.
The alternation of light and dark periods on a daily or seasonal time scale is of utmost importance for the synchronization of physiological and behavioral processes in the environment. For the last 2 decades , artificial light at night (ALAN) has strongly increased worldwide, disrupting the photoperiod and its related physiological processes, and impacting the survival and reproduction of wild animals. ALAN is now considered as a major concern for biodiversity and human health. Here, we present why insects are relevant biological models to investigate the impact of ALAN. First the phenotypic responses to ALAN and their underpinning mechanisms are reviewed. The consequences for population dynamics, and the community composition and functioning are described in the second part. Because ALAN provides new and widespread selective pressure, we inventory evolutionary changes in response to this anthropogenic change. Finally, we identify promising future avenues, focusing on the necessity of understanding evolutionary processes that could help stakeholders consider darkness as a resource to preserve biodiversity as well as numerous ecosystem services in which insects are involved.
In this paper, we are presenting a short overview of the sensors and sensor fusion in autonomous vehicles. We focused on the sensor fusion from the key sensors in autonomous vehicles: camera, radar, and lidar. The current state-of-the-art in this area will be presented, such as 3D object detection method for leveraging both image and 3D point cloud information, moving object detection and tracking system, and occupancy grid mapping used for navigation and localization in dynamic environments. It is shown that including more sensors into sensor fusion system benefits with better performance and the robustness of the solution. Moreover, usage of camera data in localization and mapping, that is traditionally solved by radar and lidar data, improves the perceived model of the environment. Sensor fusion has a crucial role in autonomous systems overall, therefore this is one of the fastest developing areas in the autonomous vehicles domain.
In recent decades, advances in lighting technology have precipitated exponential increases in night sky brightness worldwide, raising concerns in the scientific community about the impact of artificial light at night (ALAN) on crepuscular and nocturnal biodiversity. Long‐term records show that insect abundance has declined significantly over this time, with worrying implications for terrestrial ecosystems. The majority of investigations into the vulnerability of nocturnal insects to artificial light have focused on the flight‐to‐light behavior exhibited by select insect families. However, ALAN can affect insects in other ways as well. This review proposes five categories of ALAN impact on nocturnal insects, highlighting past research and identifying key knowledge gaps. We conclude with a summary of relevant literature on bioluminescent fireflies, which emphasizes the unique vulnerability of terrestrial light‐based communication systems to artificial illumination. Comprehensive understanding of the ecological impacts of ALAN on diverse nocturnal insect taxa will enable researchers to seek out methods whereby fireflies, moths, and other essential members of the nocturnal ecosystem can coexist with humans on an increasingly urbanized planet.
Background
Avian collisions with man-made objects and vehicles (e.g., buildings, cars, airplanes, power lines) have increased recently. Lights have been proposed to alert birds and minimize the chances of collisions, but it is challenging to choose lights that are tuned to the avian eye and can also lead to avoidance given the differences between human and avian vision. We propose a choice test to address this problem by first identifying wavelengths of light that would over-stimulate the retina using species-specific perceptual models and by then assessing the avoidance/attraction responses of brown-headed cowbirds to these lights during daytime using a behavioral assay.
Methods
We used perceptual models to estimate wavelength-specific light emitting diode (LED) lights with high chromatic contrast. The behavioral assay consisted of an arena where the bird moved in a single direction and was forced to make a choice (right/left) using a single-choice design (one side with the light on, the other with the light off) under diurnal light conditions.
Results
First, we identified lights with high saliency from the cowbird visual perspective: LED lights with peaks at 380 nm (ultraviolet), 470 nm (blue), 525 nm (green), 630 nm (red), and broad-spectrum (white) LED lights. Second, we found that cowbirds significantly avoided LED lights with peaks at 470 and 630 nm, but did not avoid or prefer LED lights with peaks at 380 and 525 nm or white lights.
Discussion
The two lights avoided had the highest chromatic contrast but relatively lower levels of achromatic contrast. Our approach can optimize limited resources to narrow down wavelengths of light with high visual saliency for a target species leading to avoidance. These lights can be used as candidates for visual deterrents to reduce collisions with man-made objects and vehicles.
The brighter nights have posed new challenges to the wild species by affecting their temporal physiology. The present study on Indian weaver bird (Ploceus philippinus) investigated if exposure to bright light at different phases of night affects their clock‐mediated daily functions. Birds were placed individually in specially designed activity cages under short days and long nights (8L:16D; L = 100 lux, D < 0.1 lux) for ∼3 weeks (19 days). Thereafter, they were divided into four groups (n = 6–9), and given ∼2 lux light either for the entire night (ZT 08–24; zeitgeber time 0 = time of light on; pattern A) or for 4 hr (pattern B), placed in 16 hr night such that its onset coincides with the onset of night (early night group, ZT 08–12), its end with the end of night (late night group, ZT 20–24), or the night was interrupted in the middle (midnight group, ZT 14–18). The results showed that bright light in entire night induced early onset of day activity and fragmented rest at night, however, if given at different phases of night, it made the days longer by delaying end (early night group) or advancing onset of daily activity (late night group). It also suppressed the melatonin levels and increased body temperature. These results suggest that bright light at night alters the perception of daylength and affects the underlying physiology. The findings may be useful in adopting a strategy for use of night light without disturbing species fitness in their environment.
Light sources attract nocturnal flying insects, but some lamps attract more insects than others. The relation between the properties of a light source and the number of attracted insects is, however, poorly understood. We developed a model to quantify the attractiveness of light sources based on the spectral output. This model is fitted using data from field experiments that compare a large number of different light sources. We validated this model using two additional datasets, one for all insects and one excluding the numerous Diptera. Our model facilitates the development and application of light sources that attract fewer insects without the need for extensive field tests and it can be used to correct for spectral composition when formulating hypotheses on the ecological impact of artificial light. In addition, we present a tool allowing the conversion of the spectral output of light sources to their relative insect attraction based on this model.
For many decades, the spectral composition of lighting was determined by the type of lamp, which also influenced potential effects of outdoor lights on species and ecosystems. Light‐emitting diode (LED) lamps have dramatically increased the range of spectral profiles of light that is economically viable for outdoor lighting. Because of the array of choices, it is necessary to develop methods to predict the effects of different spectral profiles without conducting field studies, especially because older lighting systems are being replaced rapidly. We describe an approach to predict responses of exemplar organisms and groups to lamps of different spectral output by calculating an index based on action spectra from behavioral or visual characteristics of organisms and lamp spectral irradiance. We calculate relative response indices for a range of lamp types and light sources and develop an index that identifies lamps that minimize predicted effects as measured by ecological, physiological, and astronomical indices. Using these assessment metrics, filtered yellow‐green and amber LEDs are predicted to have lower effects on wildlife than high pressure sodium lamps, while blue‐rich lighting (e.g., K ≥ 2200) would have greater effects. The approach can be updated with new information about behavioral or visual responses of organisms and used to test new lighting products based on spectrum. Together with control of intensity, direction, and duration, the approach can be used to predict and then minimize the adverse effects of lighting and can be tailored to individual species or taxonomic groups. The intersection of response curves and lamp spectra describes potential impacts of nighttime lighting on insects, sea turtles, Newell's Shearwater, and juvenile salmon, as well as their average, compared with equal brightness in lux of daylight (D65; 6500K) within the range 350–780 nm.
Many visual animals exploit spectral information for seeking food and mates, for identifying preys and predators, and for navigation. Animals use chromatic information in two ways. “True color vision,” the ability to discriminate visual stimuli on the basis of their spectral content independent of brightness, is thought to play an important role in object identification. In contrast, “wavelength-specific behavior,” which is strongly dependent on brightness, often associates with foraging, navigation, and other species-specific needs. Among animals capable of chromatic vision, insects, with their diverse habitats, stereotyped behaviors, well-characterized anatomy and powerful genetic tools, are attractive systems for studying chromatic information processing. In this review, we first discuss insect photoreceptors and the relationship between their spectral sensitivity and animals’ color vision and ecology. Second, we review recent studies that dissect chromatic circuits and explore neural mechanisms of chromatic information processing. Finally, we review insect behaviors involving “true color vision” and “wavelength-specific behaviors,” especially in bees, butterflies, and flies. We include examples of high-order color vision, such as color contrast and constancy, which are shared by vertebrates. We focus on Drosophila studies that identified neuronal correlates of color vision and innate spectral preferences. We also discuss the electrophysiological studies in bees that reveal color encoding. Despite structural differences between insects’ and vertebrates’ visual systems, their chromatic vision appears to employ the same processing principles, such as color opponency, suggesting convergent solutions of neural computation to common problems.
With many of the world's migratory bird populations in alarming decline, broad-scale assessments of responses to migratory hazards may prove crucial to successful conservation efforts. Most birds migrate at night through increasingly light-polluted skies. Bright light sources can attract airborne migrants and lead to collisions with structures, but might also influence selection of migratory stopover habitat and thereby acquisition of food resources. We demonstrate, using multi-year weather radar measurements of nocturnal migrants across the northeastern U.S., that autumnal migrant stopover density increased at regional scales with proximity to the brightest areas, but decreased within a few kilometers of brightly-lit sources. This finding implies broad-scale attraction to artificial light while airborne, impeding selection for extensive forest habitat. Given that high-quality stopover habitat is critical to successful migration, and hindrances during migration can decrease fitness, artificial lights present a potentially heightened conservation concern for migratory bird populations.
Sodium street lights, dominated by long wavelengths of light, are being replaced by broad‐spectrum, white lights globally, in particular light‐emitting diodes ( LED s). These white lights typically require less energy to operate and are therefore considered “eco‐friendly”. However, little attention has been paid to the impacts white lights may have upon local wildlife populations.
We compared insect attraction to orange (high‐pressure sodium, HPS ) and white (metal halide, MH and LED ) street lights experimentally using portable street lights and custom‐made flight intercept traps.
Significantly more (greater than five times as many) insects were attracted to white MH street lights than white (4,250 K) LED and HPS lights. There was no statistical difference in the numbers of insects attracted to LED and HPS lights for most taxa caught. However, rarefaction shows a greater diversity of insects caught at LED than HPS lights.
Policy implications . With the current, large‐scale conversion to white light‐emitting diode ( LED ) lighting, our results give insight into how changes to street light technology may affect wildlife populations and communities. We recommend avoiding metal halide light installations as they attract many more insects than competing technologies. We highlight the need to tailor LED lighting to prevent disturbances across multiple insect taxa.
When an artificial surface (e.g. an asphalt road) reflects strongly and horizontally polarized light as water bodies do in the nature, polarotactic aquatic insects, like the creek-dwelling Ephemera danica mayflies easily become deceived. After swarming above the creek surface, E. danica females begin their upstream compensatory flight and can be deflected at bridges with an asphalt road and continue their flight above the road surface. Thus, the water-mimicking optical signal of the road may deceive water-seeking polarotactic mayflies and lead them to distant, polarized-light-polluting surfaces, which elicit anomalous oviposition. On an asphalt road crossing a creek, we deployed polarizing insect traps at different distances from the bridge. The traps captured E. danica mayflies and their catch numbers indicated that these mayflies originated from the direction of the bridge, proving that they followed the track of the road. Our results suggest that distant polarized-light-polluting objects along an asphalt road can trap mayflies emerging from a creek crossing the road. The combination of an asphalt road and a man-made in situ (local) polarizing surface forms a complex ecological trap, being capable of luring aquatic insects from greater distances. To eliminate the oviposition of dangered polarotactic aquatic insects emerging from a creek onto the asphalt road crossing the creek, we suggest to deploy strongly and horizontally polarizing water-filled black trays along the edge of the road during the swarming period. Thus, the eggs of the deceived insects can be moved back to the creek in order to assist the conservation of the offspring-generation.
Artificial light at night has shown a remarkable increase over the past decades. Effects are reported for many species groups, and include changes in presence, behaviour, physiology and life-history traits. Among these, bats are strongly affected, and how bat species react to light is likely to vary with light colour. Different spectra may therefore be applied to reduce negative impacts. We used a unique set-up of eight field sites to study the response of bats to three different experimental light spectra in an otherwise dark and undisturbed natural habitat. We measured activity of three bat species groups around transects with light posts emitting white, green and red light with an intensity commonly used to illuminate countryside roads. The results reveal a strong and spectrum-dependent response for the slowflying Myotis and Plecotus and more agile Pipistrellus species, but not for Nyctalus and Eptesicus species. Plecotus and Myotis species avoided white and green light, but were equally abundant in red light and darkness. The agile, opportunistically feeding Pipistrellus species were significantly more abundant around white and green light, most likely because of accumulation of insects, but equally abundant in red illuminated transects compared to dark control. Forest-dwelling Myotis and Plecotus species and more synanthropic Pipistrellus species are thus least disturbed by red light. Hence, in order to limit the negative impact of light at night on bats, white and green light should be avoided in or close to natural habitat, but red lights may be used if illumination is needed. © 2017 The Author(s) Published by the Royal Society. All rights reserved.
One major, yet poorly studied, change in the environment is nocturnal light pollution, which strongly alters habitats of nocturnally active species. Artificial night lighting is often considered as driving force behind rapid moth population declines in severely illuminated countries. To understand these declines, the question remains whether artificial light causes only increased mortality or also sublethal effects. We show that moths subjected to artificial night lighting spend less time feeding than moths in darkness, with the shortest time under light conditions rich in short wavelength radiation. These findings provide evidence for sublethal effects contributing to moth population declines. Because effects are strong under various types of light compared with dark conditions, the potential of spectral alterations as a conservation tool may be overestimated. Therefore, restoration and maintenance of darkness in illuminated areas is essential for reversing declines of moth populations.
Autonomous vehicles are expected to play a key role in the future of urban transportation systems, as they offer potential for additional safety, increased productivity, greater accessibility, better road efficiency, and positive impact on the environment. Research in autonomous systems has seen dramatic advances in recent years, due to the increases in available computing power and reduced cost in sensing and computing technologies, resulting in maturing technological readiness level of fully autonomous vehicles. The objective of this paper is to provide a general overview of the recent developments in the realm of autonomous vehicle software systems. Fundamental components of autonomous vehicle software are reviewed, and recent developments in each area are discussed.
Automated driving can fundamentally change road transportation and improve quality of life. However, at present, the role of humans in automated vehicles (AVs) is not clearly established. Interviews were conducted in April and May 2015 with twelve expert researchers in the field of Human Factors (HF) of automated driving to identify commonalities and distinctive perspectives regarding HF challenges in the development of AVs. The experts indicated that an AV up to SAE Level 4 should inform its driver about the AV’s capabilities and operational status, and ensure safety while changing between automated and manual modes. HF research should particularly address interactions between AVs, human drivers, and vulnerable road users. Additionally, driver training programs may have to be modified to ensure that humans are capable of using AVs. Finally, a reflection on the interviews is provided, showing discordance between the interviewees’ statements—which appear to be in line with a long history of human factors research—and the rapid development of automation technology. We expect our perspective to be instrumental for stakeholders involved in AV development and instructive to other parties.
Since the invention of the electric light bulb in 1879, a significant portion of the planet has been transformed from experiencing a natural pattern of light and dark determined by the sun, moon, stars and occasional other transient lights to being subjected to intermittent and perpetual illumination from human civilisation that is unprecedented in the history of Earth. The pervasiveness of this phenomenon and its exponential growth has measurable and significant consequences for living organisms. The results of recent research have extended knowledge about the geographic scope and specific impacts of artificial night lighting on animal behaviour, physiological processes and ecological interactions across a range of taxa and its broader ecosystem effects.
Key Concepts
Artificial lighting alters natural patterns of light and dark over large areas of Earth's surface.
Most species have circadian rhythms that are entrained by cycles of light and dark that can be affected by artificial lighting.
Organisms vary widely in their perception of intensity and wavelengths of light; what is perceived as ‘dark’ by humans may be bright to another species.
Many species specialise in activities in particular lighting conditions (either day versus night or illumination levels during a month or during the course of a night) and this temporal partitioning can be disrupted by artificial lighting.
Nocturnal processes of repair and recovery, including production of essential hormones such as melatonin, can be interrupted by artificial night lighting.
Decisions to forage at night are related to lighting levels; species weigh the risk of predation against need to seek food.
Additional light at night tends to favour predators, except when groups of prey species, such as a flock of birds or a school of fish, exhibit a communal vigilance for predators.
Artificial lighting can interfere with spatial orientation of organisms, resulting in direct mortality or unnecessary movements (e.g. migrating birds, hatchling sea turtles, insects at lights).
Adverse effects of artificial night lighting can be reduced through careful consideration of need, spectrum, intensity, direction and duration of light used.
Soybean development is controlled by environmental factors, primarily photoperiod and temperature. To date, photoperiod effects on flowering have been well studied but the performances and mechanism of postflowering photoperiod responses have not been fully understood, especially for the photoperiod effects on vegetative growth after flowering. In the present study, the responses of vegetative growth and reproductive development in soybean to different postflowering photoperiod regimes were investigated in four separate experiments. Three varieties of different maturity groups (MG) including the early (Dongnong 36, MG 000), medium (Dandou 5, MG IV), and late (Zigongdongdou, MG IX) were exposed to two photoperiods, short (10, 12 h) and long (15, 16 or 18 h). The results showed that postflowering photoperiod not only regulated reproductive development but also affected vegetative growth. Even when flowers and pods were removed, short-day (SD) treatment promoted leaf senescence. The onset of leaf senescence among varieties tested appeared to be dependent on photoperiod sensitivity. Leaf senescence of the late-maturing variety of Zigongdongdou (sensitive to photoperiod) was delayed more significantly than that of the medium and early-maturing varieties (less sensitive to photoperiod). Long-day (LD) treatments delayed leaf senescence and seed maturation in the late-maturing variety of Zigongdongdou plants with only the SD-induced leaves produced before flowering. LD treatments imposed from the beginning bloom, beginning pod setting or beginning seed filling delayed leaf senescence and seed maturation of late-maturing soybean variety (Zigongdongdou). Results of night-break with red (R) and far-red (FR) light demonstrated that postflowering photoperiod responses of soybean were R/FR reversible reactions and the phytochromes seemed to be functional as receptors of photoperiod signals even after flowering. It was proposed that the regulation of photoperiod on development of soybean was effective from emergence through maturation, and the postflowering photoperiod signals were also mediated by phytochromes similar to those before flowering. The flowering reversion in late-MG soybean varieties under LD was a directresult of LD and was not due to secondary effect of abscission of pods and flowers. Soybean leaves not only received SD signals but also LD signals; furthermore, the LD effects reversed the SD effects and vice versa.
LED lighting is predicted to constitute 70% of the outdoor and residential lighting markets by 2020. While the use of LEDs promotes energy and cost savings relative to traditional lighting technologies, little is known about the effects these broad-spectrum “white” lights will have on wildlife, human health, animal welfare, and disease transmission. We conducted field experiments to compare the relative attractiveness of four commercially available “domestic” lights, one traditional (tungsten filament) and three modern (compact fluorescent, “cool-white” LED and “warm-white” LED), to aerial insects, particularly Diptera. We found that LEDs attracted significantly fewer insects than other light sources, but found no significant difference in attraction between the “cool-” and “warm-white” LEDs. Fewer flies were attracted to LEDs than alternate light sources, including fewer Culicoides midges (Diptera: Ceratopogonidae). Use of LEDs has the potential to mitigate disturbances to wildlife and occurrences of insect-borne diseases relative to competing lighting technologies. However, we discuss the risks associated with broad-spectrum lighting and net increases in lighting resulting from reduced costs of LED technology.
Today’s conventionally manufactured vehicles have a range of driving aids that help keep the vehicle safe. The operation of these features depends primarily on the proper functioning of sensors, which continuously monitor surroundings to detect obstacles. However, these sensors are not always reliable. The aim of this article is to investigate the actual limits of automatic emergency braking (AEB) when a pedestrian enters the roadway, which in many cases is unpredictable, sudden, and not automatically controlled. The expected high efficiency of AEB is significantly affected by both the speed of the vehicle and weather conditions. The conclusion of this study, therefore, is used to develop a discussion on urban speed limits and their impacts on vulnerable road users.
Objective
Automatic emergency braking (AEB) that detects pedestrians has great potential to reduce pedestrian crashes. The objective of this study was to examine its effects on real-world police-reported crashes.
Methods
Two methods were used to assess the effects of pedestrian-detecting AEB on pedestrian crash risk. Vehicles with and without the system were examined on models where it was an optional feature. Poisson regression was used to estimate the effects of AEB on pedestrian crash rates per insured vehicle year, and quasi-induced exposure using logistic regression compared involvement in pedestrian crashes to a system-irrelevant crash type.
Results
AEB with pedestrian detection was associated with significant reductions of 25%–27% in pedestrian crash risk and 29%–30% in pedestrian injury crash risk. However, there was not evidence that that the system was effective in dark conditions without street lighting, at speed limits of 50 mph or greater, or while the AEB-equipped vehicle was turning.
Conclusions
Pedestrian-detecting AEB is reducing pedestrian crashes, but its effectiveness could be even greater. For the system to make meaningful reductions in pedestrian fatalities, it is crucial for it to work well in dark and high-speed conditions. Other proven interventions to reduce pedestrian crashes under challenging circumstances, such as improved headlights and roadway-based countermeasures, should continue to be implemented in conjunction with use of AEB to prevent pedestrian crashes most effectively.
In 2015, there were 319,195 police reported vehicle-animal crashes, resulting in 275 vehicle occupant fatalities. Animal-detecting automatic emergency braking (AEB) systems are a promising active safety measure which could potentially avoid or mitigate many of these crashes by warning the driver, utilizing automatic braking, or both. The purpose of this study was to develop and characterize a target population of vehicle-animal crashes applicable to AEB systems and to analyze the potential benefits of an animal-detecting AEB system. The study was based on two nationally representative databases, Fatality Analysis Reporting System and the National Automotive Sampling System’s General Estimates System, and a naturalistic driving study, SHRP 2. The target population was restricted to vehicle-animal crashes that were forward impacts or road departures and involved cars and light trucks, with no loss of control. Crash characteristics which may influence the performance of AEB such as lighting, weather, pre-crash movement, relation to junction, and first and worst harmful events, were analyzed. The study found that the major influences on the effectiveness of animal AEB systems were: weather, lighting, pre-crash movements, and the crash location. Six potential target populations were used to analyze the potential effectiveness of an animal AEB system, with effectiveness ranging between 21.6% and 97% of police reported crashes and between 4.1% and 50.8% of fatal vehicle-animal crashes. An AEB system’s ability to function in low light and poor weather conditions may enable it to avoid a substantially higher proportion of crashes.
Artificial light at night (ALAN) is increasing at a high rate across the globe and can cause shifts in animal phenology due to the alteration of perceived photoperiod. Birds in particular may be highly impacted due to their use of extra-retinal photoreceptors, as well as the use of photoperiodic cues to time life events such as reproduction, moult, and migration. For the first time, we used light-logging geolocators to determine the amount of ALAN experienced by long-distance migratory songbirds (purple martin; Progne subis) while at their overwintering sites in South America to measure its potential relationship with spring migration timing. Almost a third of birds (48/155; 31%) were subjected to at least one night with ALAN over 30 days prior to spring migration. Birds that experienced the highest number of nights (10+) with artificial light departed for spring migration on average 8 days earlier and arrived 8 days earlier at their breeding sites compared to those that experienced no artificial light. Early spring migration timing due to pre-migration ALAN experienced at overwintering sites could lead to mistiming with environmental conditions and insect abundance on the migratory route and at breeding sites, potentially impacting survival and/or reproductive success. Such effects would be particularly detrimental to species already exhibiting steep population declines such as purple martins and other migratory aerial insectivores.
How to predict and calculate the positions of stars, planets, the sun, the moon, and satellites using a personal computer and high school mathematics.
Our knowledge of the universe is expanding rapidly, as space probes launched decades ago begin to send information back to earth. There has never been a better time to learn about how planets, stars, and satellites move through the heavens. This book is for amateur astronomers who want to move beyond pictures of constellations in star guides and solve the mysteries of a starry night. It is a book for readers who have wondered, for example, where Saturn will appear in the night sky, when the sun will rise and set, or how long the space station will be over their location. In Celestial Calculations, J. L. Lawrence shows readers how to find the answers to these and other astronomy questions with only a personal computer and high school math. Using an easy-to-follow step-by-step approach, Lawrence explains what calculations are required, why they are needed, and how they all fit together.
Lawrence begins with basic principles: unit of measure conversions, time conversions, and coordinate systems. He combines these concepts into a computer program that can calculate the location of a star, and uses the same methods for predicting the locations of the sun, moon, and planets. He then shows how to use these methods for locating the many satellites we have sent into orbit. Finally, he describes a variety of resources and tools available to the amateur astronomer, including star charts and astronomical tables. Diagrams illustrate the major concepts, and computer programs that implement the algorithms are included. Photographs of actual celestial objects accompany the text, and interesting astronomical facts are interspersed throughout.
Source code (in Python 3, JAVA, and Visual Basic) and executables for all the programs and examples presented in the book are available for download at https://CelestialCalculations.github.io.
Artificial light at night can disrupt sleep in humans [1, 2, 3, 4] and other animals [5, 6, 7, 8, 9, 10]. A key mechanism for light to affect sleep is via non-visual photoreceptors that are most sensitive to short-wavelength (blue) light [11]. To minimize effects of artificial light on sleep, many electronic devices shift from white (blue-rich) to amber (blue-reduced) light in the evening. Switching outdoor lighting from white to amber might also benefit wildlife [12]. However, whether these two colors of light affect sleep similarly in different animals remains poorly understood. Here we show, by measuring brain activity, that both white and amber lighting disrupt sleep in birds but that the magnitude of these effects differs between species. When experimentally exposed to light at night at intensities typical of urban areas, domestic pigeons (Columba livia) and wild-caught Australian magpies (Cracticus tibicen tyrannica) slept less, favored non-rapid eye movement (NREM) sleep over REM sleep, slept less intensely, and had more fragmented sleep compared to when lights were switched off. In pigeons, these disruptive effects on sleep were similar for white and amber lighting. For magpies, however, amber light had less impact on sleep. Our results demonstrate that amber lighting can minimize sleep disruption in some birds but that this benefit may not be universal.
After decreasing for three decades, U.S. pedestrian fatalities increased by more than 40% between 2009 and 2016, hindering progress toward a future transportation system that produces zero deaths. While many researchers have investigated changes in the last decade, this study takes a long-term perspective and asks: what are the most common characteristics associated with U.S. pedestrian fatalities, and how have these characteristics shifted over the last 40 years? It analyzes all 231,675 pedestrian fatalities recorded between 1977 and 2016 in the Fatality Analysis Reporting System (FARS) database. Over 40 years, most pedestrian fatalities occurred in darkness (65%) and involved male pedestrians (70%) and male drivers (67%). They were commonly in roadway lanes (90%), away from intersections (80%), and involved vehicles traveling straight (83%). Most occurred on roadways with speed limits of 35 mph (56 km/h) or higher (70%) and four or more lanes (50%). Trends were compared across eight 5-year periods. Between the earliest and latest periods, there were significant decreases in the proportion of pedestrian fatalities among children younger than 15 (from 18% to 5%) and involving drivers who were drinking (from 15% to 8%). There were significant increases in pedestrian fatalities during darkness (from 63% to 73%), involving large vehicles (e.g., pickup trucks, vans, and SUVs) (from 22% to 44%), on roadways with speed limits 35 mph or higher (from 60% to 76%), and on roadways with four or more lanes (from 41% to 58%). These findings underscore the need for fundamental transportation systems changes to ultimately eliminate pedestrian fatalities.
Nighttime safety continues to be a major concern for transportation agencies across the country. Roadway lighting has been widely used as a countermeasure for nighttime crashes. However, safetyengineers and researchers frequently lack effective tools when determining exactly how lighting should be optimized to maximize safety while conserving energy. This project involved an extensive effort to investigate traffic safety lighting impacts at intersections. Based on the results, the project identified optimal lighting levels for different types of intersections and developed guidelines to facilitate lighting needs analysis and design at the Virginia Department of Transportation. During this study,a crash analysis showed a 2.9% reduction in night-to-day crash ratio for each 1-lux increase of minimum illuminance at intersection boxes. Additionally, the project team found a benefit-cost ratiobetween 2.6 and 5.6for unsignalized intersections and between 2.8 and 7.9 for signalized intersections, assuming one injury nighttime crash per year at such locations and depending on whether existing poles can be used.
Vehicle headlamps and roadway lighting are the major sources of illumination at night. These sources affect contrast - defined as the luminance difference of an object from its background - which drives visibility at night. However, the combined effect of vehicle headlamps and intersection lighting on object contrast has not been reported previously. In this study, the interactive effects of vehicle headlamps and overhead lighting on object contrast were explored based on earlier work that examined drivers’ visibility under three intersection lighting designs (illuminated approach, illuminated box, and illuminated approach + box). The goals of this study were to: 1) quantify object luminance and contrast as a function of a vehicle’s headlamps and its distance to an intersection using the three lighting designs; and, 2) to assess whether contrast influences visual performance and perceived visibility in a highly dynamic intersection environment. Both luminance and contrast of roadway visibility targets and a pedestrian were measured with a calibrated photometer at a realistic intersection. Both target and pedestrian contrast and luminance were substantially affected by the intersection lighting configuration, illuminance level, location at the intersection, and vehicle distance from the intersection. Objects also underwent changes in contrast polarity (positive to negative or vice-versa) as the distance between the vehicle and object changed. During these polarity transitions, objects became invisible because the contrast was zero. Negative contrast on targets was associated with higher visual performance. Within a given contrast polarity (positive vs. negative), visual performance depended on the magnitude of contrast, with higher contrast associated with higher visual performance. The relationship between pedestrian contrast and perceived visibility was complex, since pedestrians were often rendered in multiple contrasts. These findings have important implications for the lighting design of intersections and the development of nighttime pedestrian detection systems that rely on computer vision.
In an attempt to improve cost-effectiveness, it has become increasingly popular to adapt wildlife crossing structures to enable people to also use them for safe passage across roads. However, the required needs of humans and wildlife may conflict, resulting in a structure that does not actually provide the perceived improvement in cost-effectiveness, but instead a reduction in conservation benefits. For example, lighting within crossing structures for human safety at night may reduce use of the structure by nocturnal wildlife, thus contributing to barrier and mortality effects of roads rather than mitigating them.
In this study, we experimentally evaluated the impact of artificial light at night on the rate of use of wildlife crossing structures, specifically underpasses, by ten insectivorous bat species groups in south-eastern Australia. We monitored bat activity before, during and after artificially lighting the underpasses. We found that bats tended to avoided lit underpasses, and only one species consistently showed attraction to the light. Artificial light at night in underpasses hypothetically increases the vulnerability of bats to road-mortality or to the barrier effect of roads. The most likely outcomes of lighting underpasses were 1. an increase in crossing rate above the freeway and a decrease under the underpasses, or 2. a reduction in crossing rate both above freeways and under the underpasses, when structures were lit. Our results corroborate those of studies on terrestrial mammals, and thus we recommend that underpasses intended to facilitate the movement of wildlife across roads should not be lit.
Insects around the world are rapidly declining. Concerns over what this loss means for food security and ecological communities have compelled a growing number of researchers to search for the key drivers behind the declines. Habitat loss, pesticide use, invasive species, and climate change all have likely played a role, but we posit here that artificial light at night (ALAN) is another important—but often overlooked—bringer of the insect apocalypse. We first discuss the history and extent of ALAN, and then present evidence that ALAN has led to insect declines through its interference with the development, movement, foraging, and reproductive success of diverse insect species, as well as its positive effect on insectivore predation. We conclude with a discussion of how artificial lights can be tuned to reduce their impact on vulnerable populations. ALAN is unique among anthropogenic habitat disturbances in that it is fairly easy to ameliorate, and leaves behind no residual effects. Greater recognition of the ways in which ALAN affects insects can help conservationists reduce or eliminate one of the major drivers of insect declines.
Animal-vehicle collisions (AVCs) are a growing problem in the United States, resulting in countless loss of animal life and considerable human injury and death every year, especially to motorcyclists. Due to underreporting, collision data generally provide a very low (highly biased) estimate of actual AVC counts and often lack key details, such as the species of animals involved. However, AVC reports cover entire states and nations, and can illuminate differences in wild versus domestic animal-vehicle collisions through statistical and spatial analysis.
51,522 animal-related crashes were reported to Texas police from 2010 through 2016, at a total cost over $1.3 billion annually to Texas motorists – not including the value of lost animal lives. AVC reports jump twice a day: between 5 and 8 AM and between 5 and 10 PM. Motorists are also significantly more likely to collide with a wild animal during the months of October, November, and December. Wildlife-vehicle collisions (WVC) are 64% of total reports, events involving domestic animals (like dogs and cattle) are 31%, and the remaining 5% of reports are unspecified. Most AVCs in the state occur at night in unlit locations, usually on rural roads with very low traffic volumes.
Using ordinary least-squares (OLS) regression analysis across Texas’ n = 254 counties, this work finds that less densely populated counties, marked as rural, and those with fewer vehicle-miles traveled (VMT) per capita but more lane-miles per capita, tend to experience the greatest number of AVCs per VMT, after controlling for county average rainfall, share of VMT onsystem roadways, job densities, and vehicle ownership (vehicles per capita).
Intervention options for the mitigation of animal-vehicle collisions are numerous and diverse. For wildlife collisions specifically, this work finds that large crossing structures (underpasses and overpasses) at the highway link level return benefit-to-cost ratios near 3.0, while their lower-cost counterparts (wildlife fencing and animal detection systems) deliver ratios up to 30.
The growing wildland‐urban interface is a frontier of human‐wildlife conflict worldwide. Where natural and developed areas meet, there is potential for negative interactions between humans and wild animals, including wildlife‐vehicle collisions. Understanding the environmental and anthropogenic factors leading to these collisions can inform transportation and habitat planning, with an objective of reducing animal mortality and human costs. We investigated spatial, temporal, and species‐specific patterns of roadkill on Interstate‐280 (I‐280) in California, USA, and examined the effects of land cover, fencing, lighting, and traffic. The highway is situated just south of San Francisco, dividing a large wildlife refuge to the west from dense residential areas to the east, and therefore presents a major barrier to wildlife movement. Areas with a higher percentage of developed land east of I‐280 and areas with more open space on the west side of I‐280 were associated with an increase in overall roadkill, suggesting that hard boundaries at the wildland‐urban interface may be zones of high risk for dispersing animals. This pattern was especially strong for raccoons ( Procyon lotor ) and black‐tailed deer ( Odocoileus hemionus ). The presence of lighting correlated with increased roadkill with the exception of coyote ( Canis latrans ). Contrary to our expectations, we found weak evidence that fencing increases roadkill, perhaps because animals become trapped on roadways or because fencing is not sufficient to block access to the road by wildlife. Finally, we found strong evidence for roadkill seasonality, correlated with differences in movement and dispersal across life‐history stages. We highlight the value of citizen‐science datasets for monitoring human‐wildlife conflict and suggest potential mitigation measures to reduce the negative effects of wildlife‐vehicle collisions for people and wildlife. © 2019 The Wildlife Society.
Integrates Vehicle, Signal, and Road Lighting into a Unified System Many people drive many miles after dark and rely on lighting to help them gather information about the road ahead and the presence and intentions of other people on and near the road. With new technology on the industry’s horizon, Lighting for Driving: Roads, Vehicle, Signs and Signals conveys the crucial role lighting plays in road safety and examines how it could be used more effectively. Authored by a lighting and visibility expert, this book explains the thinking and scientific reasoning behind various forms of lighting and analyzes their contribution to the driver’s understanding of real and potential road hazards. Filled with useful information, this resource straightforwardly addresses a wide range of safety factors encountered in real driving situations, such as weather conditions, complex signage, and driver age. It also deals with the often-ignored consequences of too much light, such as light trespass and sky glow. Comprehensively Explores the Field, Emphasizing Improved Safety Vehicle, road, sign, and signal lighting are provided to enable drivers to reach their destinations quickly and safely. However, the attention given to how these forms of lighting function is likely to change as new technology is introduced and understanding of ergonomics and human factors improves. This book effectively illustrates how these forms of lighting can be modified to work together to best provide a coherent flow of information to the driver.
Portable light towers are a significant source of glare to motorists entering a work zone. Although existing research has evaluated the effect of light tower orientation on visibility and glare, the effects of factors like mounting height, offset distance from the roadway, and number of light towers in the work zone, on visual performance and discomfort glare is not known. Understanding these relationships can help in developing illuminating guidelines for work zones that can reduce glare for drivers. The goal of this paper is to understand the effect of mounting height, offset distance to the roadway, and number of light towers in the work zone on drivers’ visual performance and discomfort glare. Participants drove through a realistic work zone and evaluated portable light towers in varying mounting heights, offset distances, and number of light towers in the work zone. Results showed that the mounting height and offset distances play a critical role in affecting the driver’s visual performance and discomfort glare rating. Portable light towers, irrespective of wattage and lumen output, at lower than a mounting height of 20 ft and closer to the roadway result in decreasing driver visual performance and increasing their discomfort glare. Portable light towers should be mounted at a height of at least 20 ft and balloon light towers with higher wattage (4,000 W and greater) and lumen output (400,000 lumens and greater) should be located at an offset distance of at least 10 ft from the roadway.
The focus of sustainable lighting tends to be on reduced CO2 emissions and cost savings, but not on the wider environmental effects. Ironically, the introduction of energy‐efficient lighting, such as light emitting diodes (LEDs), may be having a great impact on the health of wildlife. These white LEDs are generated with a high content of short‐wavelength ‘blue’ light. While light of any kind can suppress melatonin and the physiological processes it regulates, these short wavelengths are potent suppressors of melatonin. Here, we manipulated the spectral composition of LED lights and tested their capacity to mitigate the physiological and health consequences associated with their use. We experimentally investigated the impact of white LEDs (peak wavelength 448 nm; mean irradiance 2.87 W/m²), long‐wavelength shifted amber LEDs (peak wavelength 605 nm; mean irradiance 2.00 W/m²), and no lighting (irradiance from sky glow < 0.37 × 10⁻³ W/m²), on melatonin production, lipid peroxidation, and circulating antioxidant capacity in the tammar wallaby (Macropus eugenii). Night‐time melatonin and oxidative status were determined at baseline and again following 10 weeks exposure to light treatments. White LED exposed wallabies had significantly suppressed nocturnal melatonin compared to no light and amber LED exposed wallabies, while there was no difference in lipid peroxidation. Antioxidant capacity declined from baseline to week 10 under all treatments. These results provide further evidence that short‐wavelength light at night is a potent suppressor of nocturnal melatonin. Importantly, we also illustrate that shifting the spectral output to longer wavelengths could mitigate these negative physiological impacts.
Significance
Artificial light at night is a novel stimulus in the evolutionary history of nocturnal animals. Light pollution can significantly alter these organisms’ behaviors, from migration to foraging to vocal communication. Nocturnally migrating birds are particularly susceptible to artificial light because of adaptations and requirements for navigating and orienting in darkness. However, light’s effects on in-flight behaviors have not been well quantified, especially in urbanized environments. Here we report that an iconic urban light installation dramatically altered multiple behaviors of nocturnally migrating birds—but these effects disappeared when lights were extinguished. We recommend selective removal of light pollution during nights with substantial bird migration to mitigate negative effects on birds, in particular collisions with lighted structures.
Environmental endocrine disruptors (EEDs) are often consequences of human activity; however, the effects of EEDs are not limited to humans. A primary focus over the past ~30years has been on chemical EEDs, but the repercussions of non-chemical EEDs, such as artificial light at night (LAN), are of increasing interest. The sensitivity of the circadian system to light and the influence of circadian organization on overall physiology and behavior make the system a target for disruption with widespread effects. Indeed, there is increasing evidence for a role of LAN in human health, including disruption of circadian regulation and melatonin signaling, metabolic dysregulation, cancer risk, and disruption of other hormonally-driven systems. These effects are not limited to humans; domesticated animals as well as wildlife are also exposed to LAN, and at risk for disrupted circadian rhythms. Here, we review data that support the role of LAN as an endocrine disruptor in humans to be considered in treatments and lifestyle suggestions. We also present the effects of LAN in other animals, and discuss the potential for ecosystem-wide effects of artificial LAN. This can inform decisions in agricultural practices and urban lighting decisions to avoid unintended outcomes.
Nighttime crashes at intersections present a major traffic safety issue in the United States. Existing approaches to intersection lighting design do not account for a driver’s visual performance or the potential interactive effects of vehicle headlamps and roadway lighting. For effective design lighting at intersections, empirical research is required to evaluate the effects of lighting configuration (part of the intersection illuminated) and lighting levels on nighttime driver visual performance. The current study had two goals: First, to quantify visual performance in three lighting configurations (illuminating the intersection box, approach, or both) and second, to determine what lighting levels within each lighting configuration support the best visual performance. The study involved a target detection task completed at night on a realistic roadway intersection. Illuminating the intersection box led to superior visual performance, as indicated by longer target detection distances, fewer missed targets, and more targets identified within a safe stopping distance. For this lighting configuration, visual performance plateaued between 7 and 10 lx of mean intersection illuminance. These results have important implications for the design of intersection lighting at isolated/rural intersections, specifically that illuminating the intersection box is an effective strategy to increase nighttime visual performance for a wider range of driver ages and could also be an energy-efficient solution.
Christopher Kyba, Andrej Mohar and Thomas Posch seek a standard figure for moonlight illuminance.
Light pollution is rapidly increasing and can have deleterious effects on biodiversity, yet light types differ in their effect on wildlife. Among the light types used for street lamps, light‐emitting diodes (LEDs) are expected to become globally predominant within the next few years.
In a large‐scale field experiment, we recorded bat activity at 46 street lights for 12 nights each and investigated how the widespread replacement of conventional illuminants by LEDs affects urban bats: we compared bat activity at municipal mercury vapour (MV) street lamps that were replaced by LEDs with control sites that were not changed.
Pipistrellus pipistrellus was the most frequently recorded species; it was 45% less active at LEDs than at MV street lamps, but the activity did not depend on illuminance level. Light type did not affect the activity of Pipistrellus nathusii , Pipistrellus pygmaeus or bats in the Nyctalus/Eptesicus/Vespertilio (NEV) group, yet the activity of P. nathusii increased with illuminance level. Bats of the genus Myotis increased activity 4·5‐fold at LEDs compared with MV lights, but illuminance level had no effect.
Decreased activity of P. pipistrellus , which are considered light tolerant, probably paralleled insect densities around lights. Further, our results suggest that LEDs may be less repelling for light‐averse Myotis spp. than MV lights. Accordingly, the transition from conventional lighting techniques to LEDs may greatly alter the anthropogenic impact of artificial light on urban bats and might eventually affect the resilience of urban bat populations.
Synthesis and applications . At light‐emitting diodes (LEDs), the competitive advantage – the exclusive ability to forage on insect aggregations at lights – is reduced for light‐tolerant bats. Thus, the global spread of LED street lamps might lead to a more natural level of competition between light‐tolerant and light‐averse bats. This effect could be reinforced if the potential advantages of LEDs over conventional illuminants are applied in practice: choice of spectra with relatively little energy in the short wavelength range; reduced spillover by precisely directing light; dimming during low human activity times; and control by motion sensors. Yet, the potential benefits of LEDs could be negated if low costs foster an overall increase in artificial lighting.
Washington State Department of Transportation (WSDOT) evaluated continuous roadway lighting on mainline freeway segments in Washington State. An extensive literature review on the safety performance of roadway lighting was completed. As part of this research effort WSDOT developed multivariate random parameter (RP) models with specific lighting variables for continuous lighting on mainline freeway segments. Roadway lighting is often used as a countermeasure to address nighttime crashes and this research evaluates common assumption related to roadway lighting. The models developed for this research use crashes from the end of civil dusk twilight to the start of civil dawn twilight since lighting systems are of limited value outside these timeframes. Natural light conditions were estimated for crashes based on location and time of the crash event. Based on the RP results, the research team concludes that the contribution of continuous illumination to nighttime crash reduction is negligible. In addition to the findings on safety performance, a pilot LED project on US101 demonstrated that LED roadway lighting can significantly increase energy efficiency and environmental stewardship (e.g., reducing greenhouse gas emissions) while maintaining safety performance outcomes. The research team recommended modification to WSDOT design policy, including removal of the requirement of continuous mainline lighting and reduction of lighting where segment specific analysis indicates appropriate.