Assessing the safety criticality of driver behavior toward cyclists at intersections

Abstract

Objective: Detailed analyses of car-to-cyclist accidents show that drivers intending to turn right at T-junctions collide more often with cyclists crossing from the right side on the bicycle lane than drivers intending to turn left. This fact has led to numerous studies examining the behavior of drivers turning left and right. However, the most essential question still has not been sufficiently answered: is the behavior of drivers intending to turn right generally more safety critical than the behavior of those intending to turn left? The purpose of this article is to provide a method that allows to determine whether a driver’s behavior toward cyclists can retrospectively be assessed as critical or non-critical.

Methods: Several theoretical considerations enriched by findings of experimental studies were employed to devise a multi-measure method. This method was applied to a dataset containing real-world approaching behavior of 48 drivers turning right and left at four T-junctions with different sight obstructions. For each driver a behavior-specific criticality was defined based on both, their driving and gaze behavior. Moreover, based on the behavior-specific criticality of each driver, the required field of view to see a cyclist from the right was defined and was set into relation with the available field of view of the T-junction.

Results: The results show that only a small portion of the drivers within the dataset would have posed an actual risk to cyclists crossing from the right side. Those situations with a higher safety criticality did not only arise when drivers intended to turn right, but also left.

Conclusion: Therefore, the analysis can only provide an explanation for the higher proportion of accidents between drivers turning right and cyclists crossing from the right side in certain situations. Further research, for example analyses of exposure data regarding the frequency of turning manoeuvers at T-junctions, is needed in order to explain the higher proportion of accidents between drivers turning right and cyclists crossing from the right side.     

How do Consumers Perceive Electric Vehicles? A Comparison of German Consumer Groups

Abstract

Electric vehicles (EVs) are currently being discussed as a promising means to increase the energy efficiency and sustainability of today's transport systems. While technological progress and cost reduction are certainly crucial topics for their successful diffusion, consumer acceptance is another issue that warrants further analysis. Based on a large online survey (N?=?969), we compared four consumer groups which differ in their likelihood to purchase an EV with regard to their socio-demographic characteristics, their willingness to pay (WTP) and their perceptions of EVs. The findings indicate that early users in Germany are most likely to be middle-aged men living with their families in a multi-vehicle household who have a higher WTP for an EV. Perceived compatibility of an EV with personal needs seems to be the most influential factor on the stated willingness to purchase an EV. With regard to the promotion of EVs, strengthening their environmental advantages and providing financial incentives for purchase are rated as important measures by a majority of the sample, while performance characteristics which are comparable to conventional vehicles seem to be less important for most participants. Based on the data analyses, we provide recommendations for measures regarding the further development and promotion of EVs.     

A prehistoric tsunami induced long-lasting ecosystem changes on a semi-arid tropical island—the case of Boka Bartol (Bonaire, Leeward Antilles)

The Caribbean is highly vulnerable to coastal hazards. Based on their short recurrence intervals over the intra-American seas, high-category tropical cyclones and their associated effects of elevated storm surge, heavy wave impacts, mudslides and floods represent the most serious threat. Given the abundance of historical accounts and trigger mechanisms (strike-slip motion and oblique collision at the northern and southern Caribbean plate boundaries, submarine and coastal landslides, volcanism), tsunamis must be considered as well. This paper presents interdisciplinary multi-proxy investigations of sediment cores (grain size distribution, carbonate content, loss-on-ignition, magnetic susceptibility, microfauna, macrofauna) from Washington-Slagbaai National Park, NW Bonaire (Leeward Antilles). No historical tsunami is recorded for this island. However, an allochthonous marine layer found in all cores at Boka Bartol reveals several sedimentary criteria typically linked with tsunami deposits. Calibrated ¹⁴C data from these cores point to a palaeotsunami with a maximum age of 3,300 years. Alternative explanations for the creation of this layer, such as inland flooding during tropical cyclones, cannot entirely be ruled out, though in recent times even the strongest of these events on Bonaire did not deposit significant amounts of sediment onshore. The setting of Boka Bartol changed from an open mangrove-fringed embayment into a poly- to hyperhaline lagoon due to the establishment or closure of a barrier of coral rubble during or subsequent to the inferred event. The timing of the event is supported by further sedimentary evidence from other lagoonal and alluvial archives on Bonaire.     

Differential effects of temperature variability on the transmission of a marine parasite

Temperature variability is particularly pronounced in intertidal systems. The importance of considering this variability has been increasingly recognised, especially in the context of climate change and disease dynamics. Here, we investigated the effects of temperature variability on the transmission of the intertidal trematode Maritrema novaezealandensis. The experimental treatments were 15 °C (control), 15 + 5 °C daily, 15 + 10 °C every second day, 15 + 15 °C every third day (overall equal thermal loading), and a heat wave treatment (15 + 10 °C daily). Daily 6 h incubations were carried out corresponding to daytime low tides over a 12-day period. Effects on output of transmission stages (cercariae) from infected Zeacumantus subcarinatus snail hosts and transmission success of cercariae to Paracalliope novizealandiae amphipod hosts were quantified, as well as the survival of amphipods. Results showed differential effects on output and transmission success. The number of cercariae emerging was similar for treatments with equal thermal loading, but was substantially increased in the heat wave treatment. Transmission success was highest and comparable for the treatments with regular daily temperature increases (i.e. 15 + 5 °C and heat wave), compared to other treatments. Amphipod survival was not affected by temperature treatment directly, but by the number of parasites infecting an amphipod, as well as amphipod sex. These results demonstrate that cercarial output depends mostly on total thermal loading, whereas successful infection of amphipods is determined by total time above 15 °C. Repeated exposure to ~25 °C, as expected under a heat wave scenario, therefore increases both transmission pressure and success, and hence, the risk of parasite-induced mortality in amphipods.     

Using the useful: characteristics of used palms in south-eastern Ecuador

Plant families differ greatly with regard to their usefulness to humans. Within families there are also large differences in the usefulness between species; some are used for many different purposes, while most are used for few or no purposes. Which ones and to what extent species are used often varies between areas and cultural groups. To better understand variation in speciesȁ9 usefulness we studied the use of different palm species (Arecaceae) among two socio-cultural groups (one indigenous and one colonist group of mixed ethnic descent) living in the same area. We used regression and correlation analyses to determine to what degree use is related to ecological and morphological characteristics, to geographical differences in abundance, and to peopleȁ9s perceptions of speciesȁ9 availability. We found that abundance and height were the most important characteristics related to use, possibly due to the effect of height and abundance on salience, search time, and (for height) suitability for different purposes. Abundance was most important for palm heart extraction, probably due to the opportunistic nature of this activity. There was no difference between socio-cultural groups with regard to the relationship between palm abundance and use, but abundance seemed to be more decisive for people who used moderate amounts of palms. Finally, it was seen that peopleȁ9s estimates of palm abundance were not related to our measurements of abundance, which may be due to use of different spatial scales in evaluating abundance and to the subjective nature of terms such as “rare” and “abundant”.     

Maternal liver transplant: Another cause of discordant fetal sex determination using cell-free DNA

Noninvasive prenatal testing (NIPT) can very accurately determine fetal sex during pregnancy. We present an exceptional case where NIPT contradicts the ultrasound-based sex determination. The pregnant woman was recipient of a liver transplant from a male donor. Graft-derived cell-free DNA released into the maternal circulation clouded the NIPT-based sex determination. Hence, NIPT is not advisable when the pregnant mother underwent an organ transplant.     

The honey bee’s tremble dance stimulates additional bees to function as nectar receivers

If a forager bee returns to her hive laden with high-quality nectar but then experiences difficulty finding a receiver bee to unload her, she will begin to produce a conspicuous communication signal called the tremble dance. The context in which this signal is produced suggests that it serves to stimulate more bees to function as nectar receivers, but so far there is no direct evidence of this effect. We now report an experiment which shows that more bees do begin to function as nectar receivers when foragers produce tremble dances. When we stimulated the production of tremble dances in a colony and counted the number of bees engaged in nectar reception before and after the period of intense tremble dancing, we found a dramatic increase. In two trials, the number of nectar receivers rose from 17% of the colony’s population before tremble dancing to 30–50% of the population after the dancing. We also investigated which bees become the additional nectar receivers, by looking at the age composition of the receiver bees before and after the period of intense tremble dancing. We found that none of the bees recruited to the task of nectar reception were old bees, most were middle-aged bees, and some were even young bees. It remains unclear whether these auxiliary nectar receivers were previously inactive (as a reserve supply of labor) or were previously active on other tasks. Overall, this study demonstrates that a honey bee colony is able to rapidly and strongly alter its allocation of labor to adapt to environmental changes, and it further documents one of the communication mechanisms underlying this ability. Received: 31 May 1996/Accepted after revision: 9 August 1996