Lane markings in night driving: a review of past research and of the present situation

One of the basic driver tasks is to follow the road. In daytime driving, when the visibility of the road in clear weather is unobstructed, this is normally not a problem. However, when driving at night on dark roads with low beams, it is often quite difficult to see the direction the road is taking. Indeed, drivers state that poor road guidance is their main problem in night driving. To overcome this problem, roads are fitted with retroreflective pavement markings, which are visible in night driving. This study was conducted to review the role, effects, and functioning of lane marking in night driving. The report consists of five sections. Section 1 details the scope and the limitations of this report. Section 2 presents a discussion of drivers’ needs for road guidance by means of pavement markers in general and lane markings in particular. Section 3 reviews the voluminous previous research on lane markings, focusing primarily on visibility and photometric characteristics of lane markings in night driving. Section 4 provides a summary of the issues related to lane markings. Section 5 presents the general conclusions and proposals for research topics and technical developments. The overall conclusion is that while drivers need both long-range guidance (a preview time of at least 5 s) and short-range guidance (a preview time of up to 3 s), present pavement markings often offer only short-range road guidance, especially in wet road conditions. Despite the extensive past research on pavement markings, many general and specific questions remain to be answered.Michigan University, Ann Arbor, Industry Affiliation Program for Human Factors in Transportation Safetyhttp://deepblue.lib.umich.edu/bitstream/2027.42/49387/1/UMTRI-98-50.pd

Night vision enhancement systems: what should they do and what more do we need to know?

Includes bibliographical references (p. 42-48)Night vision enhancement systems (NVES, which use infrared (IR) cameras, are designed to supplement the visibility provided by standard headlamps. There are two main NVES systems: active, near infrared (NIR) systems, which require an IR source but give a complete picture of the scene in front of the driver, and passive, far infrared (FIR) systems, which do not need an IR source but only enhance relatively warm objects (such as people and animals). There are three main display alternatives: a contact analog display with the camera view superimposed on the direct view of the road by means of a head-up display (HUD), a separate HUD on the top of the dashboard, and a head-down display (HDD) in the dashboard. This report analyses what a NVES should do to improve night visibility based on night crash statistics, driver vision and visibility conditions in night driving, driver tasks and behavior, technological approaches, costs, and regulations. Potential problems with using NVES are also discussed. Finally, issues requiring future research are presented. The six main questions that need to be answered concerning NVES are: What kind of information should be presented? To whom should the information be presented? Which technological approach should be used? When should the information be presented? How should the information be presented? Where should the information be presented?Michigan University, Ann Arbor, Industry Affiliation Program for Human Factors in Transportation Safetyhttp://deepblue.lib.umich.edu/bitstream/2027.42/49459/1/UMTRI-2002-12.pd

Relative merits of the U.S. and ECE high-beam maximum intensities and of two- and four-headlamp systems

The current maximum high-beam intensity per lamp is 75,000 cd in the United States and 140,000 cd in the ECE and Japan. The primary goal of this study was to evaluate the relative merits of these two intensity levels for visibility and safety. The analysis reviewed evidence related to the following nine factors: visibility without opposing headlights, glare from opposing and following vehicles, dimming distance, sensitivity to degradation, priority between the high and low beams and within the high beam, driver eye-fixations, difference between the intensity of the low beam and the high beam, range of high beam intensities in actual traffic, and high-beam usage. Although some relevant data do not yet exist, the available information generally favors raising the U.S. maximum from 75,000 cd to the current ECE/Japanese level of 140,000 cd. It is also recommended that the minimum high-beam intensity be raised in both the U.S. and the ECE/Japanese regulations in order to improve visibility and safety. The second topic of this study, the relative merits of two- and fourheadlamp systems, is briefly discussed in the Appendix.Michigan University, Ann Arbor, Industry Affiliation Program for Human Factors in Transportation Safetyhttp://deepblue.lib.umich.edu/bitstream/2027.42/49438/1/UMTRI-2000-41.pd

Vehicle lighting and the aging population

Old drivers and old road users in general, have high injury and fatality rates in road traffic. Furthermore, the proportion of old road users and old drivers will increase rapidly during the coming decades. Night travel has proven most difficult for old persons. The purpose of this study was to analyze this situation from the vehicle lighting point of view in order to propose vehicle lighting improvements that could be of special benefit to old road users. A literature review of current knowledge concerning age, visual performance, and accident involvement was carried out. This was followed by an analysis of the present vehicle lighting problems. Based on the results from these analyses, a number of proposals for improvements were presented. The main proposals concerning illumination systems are as follows: more illumination to increase visibility in spite of higher glare, wider illumination to improve road guidance, a softer cut-off to decrease aiming sensitivity, and keeping headlights clean and correctly aimed. The main proposals concerning signaling and marking lights are the following: two intensity levels (for day and night), small, high-mounted turn signals, and higher light-source reliability. Mandatory daytime running lights are proposed. Interior lighting should be improved in a number of aspects. All of these proposed improvements should be beneficial not only for old drivers, but also for other drivers. Finally, the visibility and safety effects are estimated, research needs are pointed out, and technical and economic problems are discussed.Michigan University, Ann Arbor, Industry Affiliation Program for Human Factors in Transportation Safetyhttp://deepblue.lib.umich.edu/bitstream/2027.42/49366/1/UMTRI-98-9.pd

Nighttime visibility of retroreflective pavement markings from trucks versus cars

This nighttime field study addressed the relative visibility of retroreflective pavement markings from trucks and cars. To do that, both low-beam headlamp mounting height and observer eye height were varied. The task involved detecting the presence of a strip of retroreflective pavement marking that was moved towards a stationary observer. The main finding is that headlamp mounting height had a statistically significant effect on detection distance. Increasing the mounting height from the lowest tested level (0.6 m) to the highest tested level (1.2 m) resulted in a 19% increase in detection distance. On the other hand, there was no effect of eye height over the range tested (1.2 m to 2.4 m). Because truck headlamps are generally mounted higher than car headlamps, the present findings imply that retroreflective pavement markings are more visible (and thus more effective) for truck drivers than car drivers. Furthermore, these findings are in support of higher headlamp mounting height for all types of vehicles. However, higher headlamp mounting heights lead to more glare for both oncoming drivers and preceding drivers via rearview mirrors. Consequently, determining an optimal headlamp mounting height would require a complex weighing of both visibility and glare considerations.Michigan University, Ann Arbor, Industry Affiliation Program for Human Factors in Transportation Safetyhttp://deepblue.lib.umich.edu/bitstream/2027.42/49404/1/UMTRI-99-34.pd

What do cyclists need to see to avoid single-bicycle crashes?

The number of single-bicycle crash victims is substantial in countries with high levels of cycling. To study the role of visual characteristics of the infrastructure, such as pavement markings, in single-bicycle crashes, a study in two steps was conducted. In Study 1, a questionnaire study was conducted among bicycle crash victims (n = 734). Logistic regression was used to study the relationship between the crashes and age, light condition, alcohol use, gaze direction and familiarity with the crash scene. In Study 2, the image degrading and edge detection method (IDED-method) was used to investigate the visual characteristics of 21 of the crash scenes. The results of the studies indicate that crashes, in which the cyclist collided with a bollard or road narrowing or rode off the road, were related to the visual characteristics of bicycle facilities. Edge markings, especially in curves of bicycle tracks, and improved conspicuity of bollards are recommended. Statement of Relevance: Elevated single-bicycle crash numbers are common in countries with high levels of cycling. No research has been conducted on what cyclists need to see to avoid this type of crash. The IDED-method to investigate crash scenes is new and proves to be a powerful tool to quantify 'visual accessibility'. © 2011 Taylor & Francis

Identification of the South Saami in the Norwegian 1801 Census : Why Is the 1801 Census a Problematic Source?

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Stjärnbildning i infraröda mörka moln. Jakten efter bildning av massiva stjärnor i dess tidiga stadie

Massive stars play an important role in the formation and development of the Uni verse, affecting the evolution of galaxies and planets to a high extent. Despite their importance, much about the mechanisms of massive star formation is still unknown. Massive stars go through their evolutionary stages at a higher pace than their low mass counterparts and spend their initial stages deeply embedded in cocoons of gas and dust. Moreover, they usually form at great distances from the Earth, which makes them challenging to observe with an angular resolution sufficient to resolve their inner structures spatially. In light of all these factors, it is difficult to gain good insight into the mechanisms occurring during the early stages of massive star formation, making the validation of current theories extremely challenging. In this thesis, we aim to study the IRDC G31.98+0.07 and analyse its star formation activi ty to contribute to a better understanding of the properties of massive stars and the processes of their evolutionary stages. Data from multiple telescopes and different wavelengths were used to analyse the cloud through data mapping, cross-matching and use of mass and age models (through SED fitting and PARSEC modelling). Using IR images from Spitzer, SOFIA and Herschel telescopes, we identify 13 point like sources located across the cloud area. For 3 of these 13 cores, data at millimetre wavelengths obtained with the IRAM telescope and ALMA was used to further ana lyse the level of star formation activity. Toward these three cores, our spectral energy distribution analysis predicts masses for forming stars in the range of 8 to 32M⊙ consistent with the high-mass regime. Furthermore, the high-resolution ALMA data does not show evidence of fragmentation towards one of the cores. This may be consistent with a Core Accretion scenario. For the 13 cores, we attempt a deeper investigation using Gaia data and find a good match within the Gaia catalogue for 13 sources. For these sources, we estimate mass and age and discuss in detail the validity of our findings. In summary, the IRDC G31.98+0.07 shows some indication of massive star formation but more data is needed to further confirm our findings and draw statistically significant results

Nature, extent and ecological implications of night-time light from road vehicles

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record1.The erosion of night‐time by the introduction of artificial lighting constitutes a profound pressure on the natural environment. It has altered what had for millennia been reliable signals from natural light cycles used for regulating a host of biological processes, with impacts ranging from changes in gene expression to ecosystem processes. 2.Studies of these impacts have focused almost exclusively on those resulting from stationary sources of light emissions, and particularly streetlights. However, mobile sources, especially road vehicle headlights, contribute substantial additional emissions. 3.The ecological impacts of light emissions from vehicle headlights are likely to be especially high because these are (i) focused so as to light roadsides at higher intensities than commonly experienced from other sources, and well above activation thresholds for many biological processes; (ii) projected largely in a horizontal plane and thus can carry over long distances; (iii) introduced into much larger areas of the landscape than experience street lighting; (iv) typically broad ‘white’ spectrum, which substantially overlaps the action spectra of many biological processes; and (v) often experienced at roadsides as series of pulses of light (produced by passage of vehicles), a dynamic known to have major biological impacts. 4.The ecological impacts of road vehicle headlights will markedly increase with projected global growth in numbers of vehicles and the road network, increasing the local severity of emissions (because vehicle numbers are increasing faster than growth in the road network) and introducing emissions into areas from which they were previously absent. The effects will be further exacerbated by technological developments that are increasing the intensity of headlight emissions and the amounts of blue light in emission spectra. 5.Synthesis and applications. Emissions from vehicle headlights need to be considered as a major, and growing, source of ecological impacts of artificial night‐time lighting. It will be a significant challenge to minimize these impacts whilst balancing drivers’ needs at night and avoiding risk and discomfort for other road users. Nonetheless, there is potential to identify solutions to these conflicts, both through the design of headlights and that of roads.The research leading to this article has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no. 268504 and Natural Environment Research Council grants NE/N001672/1 and NE/P01156X/1