Slow Drivers Research Articles

Factors Influencing Traffic Accidents Involvement: A Case Study of Online Motorcycle Taxi Drivers in Banda Aceh

In Indonesia, online transportation or motorcycle taxi is often used because they can take passengers to their destination at an affordable cost. Still, along with the rise of online motorcycle taxi facilities that are not balanced with safety facilities, human factors significantly influence traffic accidents. This study aims to identify personal characteristics and driver behavior related to anxiety, aggressive driving, impatience, and violations of accident involvement in Banda Aceh city. Data collection in this study was carried out by distributing questionnaires using Google Forms aimed at online transportation drivers, as many as 200 respondents, to determine the characteristics and driving behavior. Structural Equation Modeling (SEM) method with Confirmatory Factor Analysis (CFA) model to analyze the relationship between driving behavior variables on accident involvement in Banda Aceh city. The results of respondents’ perceptions of unsafe driving behavior towards traffic accident involvement show that all indicators have a value above 2.5 on a Likert scale of 1-4. The results of CFA modeling showed that the relationship between variables Anxiety, aggressive driving, and impatience has a positive correlation value with a significant effect on accident involvement. From the modeling, the most significant indicator is the indicator “Taking the opportunity and accelerating the speed of the vehicle when the yellow light before turning red?” with a t-value of 6.996, while the impatience variable is “Feeling impatient or angry at slow drivers and wanting to get ahead of them?” with a t-value of 6.592 and “Feeling worried if you suddenly feel sleepy while driving” with a t-value of 3.598. Based on the results, it can be stated that impatience and aggressive driving lead to accident involvement.

Do Dynamic speed feedback signs impact drivers differently based on speeding tendencies? Insights from applications at select critical roadway contexts

The effects of a traffic control devices on drivers at different speed percentiles, particularly on the faster drivers, are of specific interest due to their higher likelihood of crash involvement. A study was designed to evaluate how the dynamic speed feedback signs (DSFS) affect drivers while transitioning from a high-speed to a low-speed environment. A total of 5 sites were selected, which included a freeway exit ramp, two speed transition zones, and two high-speed rural highway curves. Vehicle speed profiles approaching and entering these critical locations were collected before and after installing the DSFS. Based on the tracked speed of the free-flowing vehicles before the influence area, drivers were categorized as slower drivers, average drivers, and faster drivers using the 15th and 85th percentile speed at each site. Overall, installing the DSFS resulted in a significant reduction in speed across all locations for all sites. Drivers were found to reduce their speed while approaching the curve, traversing through the speed transition zones, and entering the curves or reduced speed limit areas. Results showed that faster drivers tend to reduce speed more than the average or slower drivers at every location. The faster drivers also reacted to the sign earlier compared to the slower or average drivers. The overall results are encouraging as they indicate that DSFS impact faster drivers more, which can ultimately reduce speeding-related crashes when transitioning from a high-speed environment. Based on the findings, the continued use of DSFS as a speed reduction strategy is recommended.

The politics of animal welfare: A scoping review of farm animal welfare governance

AbstractThe lack of research in farm animal welfare governance is noticeable given how political science traditionally describes the agricultural field as politicized, i.e., subject to private and public regulations and governance. This paper shows how this issue is making its way into social and political science by using a scoping review methodology to map and analyze what exists in the research literature on farm animal welfare governance from 2000 to 2021. In evaluating drivers in farm animal governance, the literature points to increasing public concern. This is not necessarily because it changes the public's actions, but rather give legitimacy to actors to drive change in other domains such as research and the market. This review identifies retailers and animal welfare organizations as key actors in private farm animal welfare governance. Public government and political parties are perceived as “slower drivers,” thus leaving room for private governance.

Effect of Driver Response on Efficiency of Vehicular Communication using Penalty Cost Function (EVCPCF)

Background and Objective: This study examines and takes into account three key timing factors that have an impact on the effectiveness of human-machine interfaces (HVI). A threshold-based mechanism is created to account for both cooperative driving and advanced vehicle control system (AVCS) scenarios. For AVCS and cooperative driving, the developed model takes into account on-board machine interface time, human interface time, and transmission time. Methods: A threshold function that represents the penalty cost of a slow driver reaction is presented in order to enable adaptive intelligence, enhance HVI design, and increase vehicle safety. The Penalty Cost Function (PCF) is used to make vehicle control systems intervene and take control in situations where the driver responds slowly to safety and warning messages. Additionally, this study demonstrates that AVCS-based vehicular systems are more responsive overall and are less impacted by the PCF function than cooperative systems. Results: The mathematical models created through this work allowed for a limiting efficiency value and capping for each driving scenario, according to comparative plots. This will improve the creation of more reliable control systems as part of a vehicle's mechatronics, impacting how vehicles communicate with one another in a cooperative setting. MATLAB simulation was used to verify the mathematical model. The simulation covered two limiting cases of 0.33 and 0.5 and used incrementing numbers of vehicles (10, 20, 30, 40, 50) to check the impact of increasing vehicle numbers on communication efficiency and examine whether both AVCS and AVCS with cooperative will have close levels and converge at limiting values. Conclusion: The successfully completed simulation demonstrated that throughput decreased as the number of vehicles increased, although in the limiting case, both scenarios and the driving system changed virtually by the same percentage.

The longitudinal dynamics and natural history of clonal haematopoiesis

Clonal expansions driven by somatic mutations become pervasive across human tissues with age, including in the haematopoietic system, where the phenomenon is termed clonal haematopoiesis1–4. The understanding of how and when clonal haematopoiesis develops, the factors that govern its behaviour, how it interacts with ageing and how these variables relate to malignant progression remains limited5,6. Here we track 697 clonal haematopoiesis clones from 385 individuals 55 years of age or older over a median of 13 years. We find that 92.4% of clones expanded at a stable exponential rate over the study period, with different mutations driving substantially different growth rates, ranging from 5% (DNMT3A and TP53) to more than 50% per year (SRSF2P95H). Growth rates of clones with the same mutation differed by approximately ±5% per year, proportionately affecting slow drivers more substantially. By combining our time-series data with phylogenetic analysis of 1,731 whole-genome sequences of haematopoietic colonies from 7 individuals from an older age group, we reveal distinct patterns of lifelong clonal behaviour. DNMT3A-mutant clones preferentially expanded early in life and displayed slower growth in old age, in the context of an increasingly competitive oligoclonal landscape. By contrast, splicing gene mutations drove expansion only later in life, whereas TET2-mutant clones emerged across all ages. Finally, we show that mutations driving faster clonal growth carry a higher risk of malignant progression. Our findings characterize the lifelong natural history of clonal haematopoiesis and give fundamental insights into the interactions between somatic mutation, ageing and clonal selection.

Temporal scope influences ecosystem driver-response relationships: A case study of Lake Erie with implications for ecosystem-based management

Understanding environmental driver-response relationships is critical to the implementation of effective ecosystem-based management. Ecosystems are often influenced by multiple drivers that operate on different timescales and may be nonstationary. In turn, contrasting views of ecosystem state and structure could arise depending on the temporal perspective of analysis. Further, assessment of multiple ecosystem components (e.g., biological indicators) may serve to identify different key drivers and connections. To explore how the timescale of analysis and data richness can influence the identification of driver-response relationships within a large, dynamic ecosystem, this study analyzed long-term (1969–2018) data from Lake Erie (USA–Canada). Data were compiled on multiple biological, physical, chemical, and socioeconomic components of the ecosystem to quantify trends and identify potential key drivers during multiple time intervals (20 to 50 years duration), using zooplankton, bird, and fish community metrics as indicators of ecosystem change. Concurrent temporal shifts of many variables occurred during the 1980s, but asynchronous dynamics were evident among indicator taxa. The strengths and rank orders of predictive drivers shifted among intervals and were sometimes taxon-specific. Drivers related to nutrient loading and lake trophic status were consistently strong predictors of temporal patterns for all indicators; however, within the longer intervals, measures of agricultural land use were the strongest predictors, whereas within shorter intervals, the stronger predictors were measures of tributary or in-lake nutrient concentrations. Physical drivers also tended to increase in predictive ability within shorter intervals. The results highlight how the time interval examined can filter influences of lower-frequency, slower drivers and higher-frequency, faster drivers. Understanding ecosystem change in support of ecosystem-based management requires consideration of both the temporal perspective of analysis and the chosen indicators, as both can influence which drivers are identified as most predictive of ecosystem trends at that timescale.

A Novel Macroscopic Traffic Model based on Distance Headway

A new model is proposed to characterize changes in traffic at transitions. These changes are affected by driver response. The distance headway between vehicles is considered as it affects driver behavior. Driver response is quick with a small distance headway and slow when the distance headway is large. The variations in traffic are greater with a slow driver while traffic is smooth with a quick driver. A model is developed which characterizes traffic based on driver response and distance headway. This model is compared with the well-known and widely employed Zhang and PW models. The Zhang model characterizes driver response at transitions using an equilibrium velocity distribution and ignores distance headway and driver response. Traffic flow in the PW model is characterized using only a velocity constant. Roe decomposition is employed to evaluate the Zhang, PW, and proposed models over a 270 m circular (ring) road. Results are presented which show that Zhang model provides unrealistic results. The corresponding behavior with the proposed model has large variations in flow with a slow driver but is smooth with a quick driver. The PW model provides smooth changes in flow according to the velocity constant, but the behavior is unrealistic because it is not based on traffic physics. Doi: 10.28991/CEJ-SP2021-07-03 Full Text: PDF

The Prevalence of Risky Driving Habits in Riyadh, Saudi Arabia

Road traffic crashes represent a substantial global public health issue. In Saudi Arabia, which is the focus area of this research, road traffic crashes kill over 130,000 people annually, accounting for almost 5% of deaths in that country. A cross-sectional study with 316 participants holding a valid Saudi driver’s license was conducted via the internet from December 2019 to March 2020 to collect information about the prevalence of risky driving habits among Saudi drivers. The sample was predominantly men and aged between 20 and 39, which is representative of the population of drivers in Saudi Arabia. Drivers generally reported engaging in safe behaviors, although they did state that they drove above the legal speed limit, drove aggressively around slow drivers, and became distracted while driving with some frequency. Multivariate analyses suggested men took more risks than women and younger drivers took more risks than older ones. We conclude that the behavior among drivers in Saudi Arabia generally matches those in other cultures and countries, with men and young adults taking the most risks while driving. Preventative strategies should be developed and implemented in Saudi Arabia.

Effects of Altering Mitochondrial Antioxidant Capacity on Molecular and Phenotypic Drivers of Fibrocalcific Aortic Valve Stenosis.

Background: While a small number of studies suggest that oxidative stress has an influential role in fibrocalcific aortic valve disease (FCAVD), the roles of specific antioxidant enzymes in progression of this disease remain poorly understood. Here, we focused on selectively altering mitochondrial-derived oxidative stress—which has been shown to alter progression of a myriad of age-associated diseases—on the progression of molecular and phenotypic drivers of FCAVD.Methods: We generated low-density lipoprotein receptor-deficient, Apolipoprotein B100-only mice (LA) that were either haploinsufficient for MnSOD (LA-MnSOD+/−) or genetically overexpressing MnSOD (LA-MnSODTg/0). After 6 months of Western diet feeding, mice underwent echocardiography to assess valvular and cardiac function and tissues were harvested. Quantitative-RT PCR, immunohistochemistry, and histopathology were used to measure changes in molecular pathways related to oxidative stress, calcification, and fibrosis.Results: While reductions in MnSOD increased oxidative stress, there was not an overt phenotypic effect of MnSOD deficiency on valvular and cardiac function in LA-MnSOD+/− mice. While markers of canonical bone morphogenetic protein signaling tended to increase in valve tissue from LA-MnSOD+/− (e.g., p-SMAD1/5/8 and osterix), we did not observe statistically significant increases in osteogenic signaling. We did, however, observe highly significant reductions in expression of osteopontin, which were associated with significant increases in calcium burden in LA-MnSOD+/− mice. Reciprocally, genetically increasing MnSOD did not preserve valve function in LA-MnSODTg/0, but we did observe slight reductions in p-SMAD1/5/8 levels compared to their non-transgenic littermates. Interestingly, overexpression of MnSOD dramatically increased expression of osteopontin in valve tissue from LA-MnSODTg/0 mice, but was not sufficient to attenuate calcium burden when compared to their LA-MnSOD0/0 littermates.Conclusions: Collectively, this study demonstrates that maintenance of mitochondrial antioxidant capacity is important in preventing accelerated disease progression in a mouse model of FCAVD, but that effectively altering mitochondrial antioxidant capacity as a monotherapeutic approach to slow key histopathological and molecular drivers of FCAVD remains biologically and therapeutically challenging.

Self-Reported Habitual Practices and Perceptions of Young Drivers in Sri Lanka

Crashes on the road have become a significant socio-economic problem. Younger generations, who have lesser experience in driving, are at greater risks of facing road accidents. It is therefore important to identify driving practices and perceptions of young and inexperienced drivers at an early phase of exposure so that factors that improve safe driving can be identified.This study analysed 400 young and inexperienced drivers’ self-reported habitual practices and perceptions based on a questionnaire survey. The questionnaire focused on supervision of early driving, limitation made by parents, accident and traffic offenses by these youngsters as drivers as well as other habitual driving practices. Analyses were done using reliability statistics, inter-item correlation, likelihood ratio tests, and parameter estimates. The highest inter-item correlation value was 0.467 for the pair of overtaking vehicles in restricted areas and taking the chance to speed and run a yellow light when it is about to change to red. Driving after alcohol consumption, mobile phone usage, taking an illegal U-turn at restricted areas, non-use of signals when changing lanes and overtaking a slow driver from the left side were influenced non-use of seat-belts by young drivers. These habitual practices while driving highlighted the importance of early intervention to improve road safety.In conclusion, there is always one or more habitual driving practices that have affect the other driving habits of a young driver.

Self-reports of workloads and aberrant driving behaviors as predictors of crash rate among taxi drivers: A cross-sectional study in China

Objective: Taxis provide an important mode of public transport in China, but there has been very little in-depth research on the crash involvement propensity of taxi drivers. Thus, this study was conducted to develop a quantitative model for predicting the crash rate of taxi drivers.Methods: A total of 2,391 taxi drivers from 29 companies in 4 Chinese cities completed a structured and anonymous face-to-face questionnaire reporting their demographic information, workload conditions, aberrant driving behaviors, and crash history within the 2 years prior to the survey. Using the self-reported variables, a negative binomial model was implemented to predict taxi drivers’ property damage only (PDO) and personal injury (PI) crash rates and identify the factors contributing to this risk.Results: Descriptive analysis of the survey data revealed that the workload of taxi drivers in China is relatively heavy. Seven significant predictors of PDO and PI crash rates were identified, including crossing red lights, dangerous overtaking, honking at a slow driver, failure to use an indicator lamp, driving while fatigued, stopping in forbidden areas to pick up or drop off a passenger, and driving with one hand. Taxi drivers’ average off-duty days per week, aggressive driving behaviors, and preventing another driver from merging had significant effects only on PDO crash rate, and sleep problems were found to be significantly correlated with PI crash rate.Conclusions: To improve the safety of taxi drivers, considerable measures should be strictly implemented, ranging from periodic driver training and safety education to workload reduction, with the cooperation of government agencies and taxi companies. The findings of this study contribute to the design of potentially useful policy initiatives as well as targeted safety promotion programs.

Multigroup invariance of the DAS across a random and an internet-sourced sample

It is well established that angry and, subsequently, aggressive drivers pose a problem for road safety. Over recent years, there has been an increase in the number of published studies examining driver anger, particularly using the Driving Anger Scale (DAS). The DAS measures six broad types of situations likely to provoke anger while driving (i.e., police presence, illegal driving, discourtesy, traffic obstructions, slower drivers, and hostile gestures). The majority of the recent studies have moved away from traditional paper-and-pencil methodologies, using the internet to collect data, for reasons of convenience. However, it is not yet completely clear whether data obtained from this methodology differs from more traditional methods. While research outside of the driving arena has not found substantial differences, it is important to establish whether this also applies to driving-related research and measures, such as the DAS. The present study used Multigroup Confirmatory Factor Analysis (MGCFA) to investigate the invariance of the DAS across a random sample from the electoral roll (n = 1,081: males = 45%) and an internet sourced sample (n = 627; males = 55%). The MGCFA showed the same six-factor solution was supported in both datasets. The relationships between the DAS factors and age, sex, trait anger, and annual mileage were broadly similar, although more significant differences were identified in the internet sample. This research demonstrates that driving measures administered over the internet produce similar results to those obtained using more traditional methods.

Prevalence of Psychosocial and Behavioral Aspects in Victims of Motorcycle Accidents in Civil Hospital, Karachi.

IntroductionMotorcycles are common in a developing nation like Pakistan. In addition to their benefits, motorcycles carry a high risk for accident and injury. Many factors can exacerbate the risk of motorcycle operation including the use of mobile phones while riding, a lack of knowledge of traffic rules, not following road rules or non-satisfactory vehicle health and road conditions. Along with these physical factors, some psychosocial aspects also impact risks, including aggressive behavior of drivers or variations in driving patterns associated with changes in driver mood.ObjectiveWe conducted this study to determine the association of rider/operator behavioral and psychosocial factors with motor vehicle crashes.MethodsWe conducted a cross-sectional study on the patients of Civil Hospital in Karachi, Pakistan aged between 15 to 65 years. Data were collected from 150 patients in the outpatient department and emergency room via a questionnaire assessing driver biodata, license details, socioeconomic status, and their behavioral and psychosocial conditions. Inclusion criteria were limited to patients with motorcycle accidents only; patients involved in accidents from any other form of vehicle were excluded.ResultOf the 150 patients, 70% were reported varying their driving speed with fluctuating moods, 80% rode aggressively when they have any social or financial issue, and 57% became annoyed with another driver’s behavior-all of which highlight the influence of psychosocial factors in motorcycle crashes. Concerning behavioral factors, 88% of drivers were involved in unofficial races, 44% reported overtaking slower drivers, and 80% violated traffic signals on a regular basis. These results suggest that behavioral and psychosocial factors have a major influence on the victims of motorcycle accidents and are an important cause of injury due to crashes.ConclusionPsychosocial and behavior aspects play a critical role in motorcycle accidents. Riders experiencing family-related or social-related stress and those with an aggressive personality are more prone to have a motorcycle accident than riders who do not have those stressors. Additional measures should be taken to raise awareness regarding these important contributing factors, including stress management in driving education.

Energy, rain, and the future

Climate Change The intensification of precipitation over land owing to rising atmospheric temperature is expected to increase in the 21st century, but there are still many details about why and how much that need to be better understood. Richardson et al. used a suite of climate models to analyze the atmospheric energy budget and its effects on the fast (due to atmospheric components like carbon dioxide and sulfate) and slow (due to surface temperature changes) drivers of precipitation change. They discuss likely future changes over land and sea and the causes of the past and projected trends and find that the increase may become clearly observable by around 2050. J. Clim. 31 , 9641 (2018).

The Prevalence and Correlates of Risky Driving Behavior Among National Guard Soldiers

Objective: Previous studies have reported that risky driving is associated with deployment and combat exposure in military populations, but there is limited research on risky driving among soldiers in the National Guard and Reserves, a group increasingly deployed to active international conflicts. The goal of this analysis was to assess the prevalence of risky driving and its demographic, mental health, and deployment-related correlates among members of the Ohio Army National Guard (OHARNG).Methods: The study group comprised 2,616 eligible OHARNG soldiers enlisted as of June 2008, or who enlisted between June 2008 and February 2009. The main outcome of interest was the prevalence of risky driving behavior assessed using six questions: “How often do you use seat belts when you drive or ride in a car?”; “In the past 30 days, how many times have you driven when you've had perhaps too much to drink?”; “In the past year, have you ever become impatient with a slow driver in the fast lane and passed them on the right?”; “In the past year have you crossed an intersection knowing that the traffic lights have already changed from yellow to red?”; “In the past year have you disregarded speed limits late at night or early in the morning?”; and “In the past year have you underestimated the speed of an oncoming vehicle when attempting to pass a vehicle in your own lane?” We fit multiple logistic regression models and derived the adjusted prevalence of risky driving behavior for soldiers with mental health conditions, deployment experience, exposure to combat or trauma, and psychosocial stressors or supports.Results: The prevalence of risky driving was higher in soldiers with a history of mental health conditions, deployment to a conflict area, deployment-related traumatic events, and combat or post-combat stressors. In contrast, the prevalence of risky driving was lower for soldiers who reported high levels of psychosocial support.Conclusions: Efforts to mitigate risky driving in military populations may be more effective if they incorporate both targeted messages to remediate dangerous learned driving behaviors and psychosocial interventions to build resilience and address underlying stressors and mental health symptoms.

Following slower drivers: Lead driver status moderates driver’s anger and behavioural responses and exonerates culpability

Two experiments investigated the effects of lead-driver status on the anger-experienced and aggression-expressed in traffic scenarios in which the lead drivers’ actions were determined by an event obviously beyond, or within, their control. Experiment I contrasted reactions to lead-cars bearing Learner driver markings (Low Status) or similar unmarked cars (Control), while Experiment II contrasted reactions to Ambulances (High Status) or otherwise identical generic work vans (Control). Reported anger, heart-rate and behaviour were measured while drivers drove. When the lead vehicle slowed or changed course because of the actions of another road user, drivers were reliably more angered when slowed by a learner driver than an unmarked sedan. Drivers reported less anger when slowed by an Ambulance, than by a work van, when there was no apparent cause for the lead-vehicle slowing. Driver behaviour also differed according to lead-vehicle status. Drivers allowed greater headway between themselves and a slower ambulance, but drove closer to the work-van, and followed Learner drivers at a dangerously close distance, leaving greater headway behind a similar, unmarked car. Reliable differences in subjective anger ratings and behaviour suggest that anger experienced and expressed depends not just on the actions of the perpetrator but on the perceived status of that perpetrator. Higher status vehicles appear to be forgiven their indiscretions more readily even when there are no extenuating circumstances, whilst lower status drivers are likely to be blamed more readily for circumstances beyond their control.

How the Risk-Taking Personality Influences Commute Drivers’ Departure Time Choices

This study is an empirical analysis of departure time choice behaviors of commute drivers on the basis of three month (Jul.∼Sep., 2006) data from the Electronic Toll Collection (ETC) systems in Tokyo, Japan. Assuming drivers’ risk taking personalities can be represented by their different driving behaviors, through proposing the usage of Travel Speed Standard Scores (TSSS), we firstly categorize the drivers into three groups: Fast Drivers who show a personality to take risk, Slow Drivers who show a personality to avoid risk, and Normal Drivers who are between the Fast and Slow Drivers. A comparison study is then carried on, which shows that the departure time choice behaviors between the Fast and the Slow drivers are significant different from each other. The former tends to depart later and with a smaller deviation. This paper aims helping to clarify the influence of risk taking personalities on transportation choices. © 2011 Published by Elsevier Ltd.

Dynamics of electrochemical oscillators with electrode size disparity: asymmetrical coupling and anomalous phase synchronization

Experiments are carried out in dual electrode oscillatory Ni electrodissolution in which the two electrodes have different surface areas. The transition to phase synchronization is analyzed as asymmetrical coupling strength, induced by placing a cross resistance between the electrodes, is varied. It is shown that because of nonisochronicity (phase shear, i.e., strong dependence of period on amplitude) of the oscillators, anomalous phase synchronization effects can be observed: advanced/delayed synchronization and, to a lesser extent, frequency difference enhancement. The type of synchronization is strongly affected by the underlying heterogeneities of the oscillators; in the experiments with a slow driver (large surface area) electrode the synchronization is advanced, with a fast driver electrode the synchronization is delayed with respect to symmetrical coupling. The findings thus reveal that the interplay of asymmetrical coupling with the types of inherent heterogeneities plays an important role for the interpretation of size effects in the dynamical behavior of a nonlinear chemical reaction.

Evidence for drought and forest declines during the recent megafaunal extinctions in Madagascar

AbstractAim There remains some uncertainty concerning the causes of extinctions of Madagascar’s megafauna. One hypothesis is that they were caused by over‐hunting by humans. A second hypothesis is that their extinction was caused by both environmental change and hunting. This paper systematically addresses the second hypothesis through examination of two new pollen records from south‐eastern Madagascar alongside other published records across the island.Location South‐eastern Madagascar.Methods We reconstructed past vegetation and fire dynamics over the past 6000 years at two sites in south‐eastern Madagascar (Ste‐Luce) using fossil pollen and charcoal contained in sedimentary sequences. We investigated drivers of vegetation changes and how these, in turn, influenced faunal species in the south‐east, using published climatic, archaeological and faunal records. Further, we also used published records to provide a synthesis of environmental changes on the whole island.Results Vegetation reconstructions indicate that the mosaic vegetation in the region of Ste‐Luce was highly dynamic in response to climatic changes. The open woodland, surrounding the littoral forest, transformed into an ericoid grassland between c. 5800 and 5200 cal. yr bp, possibly in response to a moderate drought recorded during this period. The littoral forest was more stable between c. 5100 and 1000 cal. yr bp, with only some minor compositional changes c. 2800 cal. yr bp and between c. 1900 and 1000 cal. yr bp. Significant forest decline, however, is observed at c. 950 cal. yr bp, coinciding with a drought and a marine surge. A comparison of these results with a synthesis of published vegetation records across the island shows asynchronous vegetation changes in response to various droughts during the Holocene, except for the 950 cal. yr bp drought event, with evidence of widespread vegetation transformations and fires across the island.Main conclusions Pronounced climatic desiccation between 1200 and 700 cal. yr bp may have been the slow driver framing and triggering vegetation transformations and decline in megafaunal populations. In addition, hunting by drought‐impacted human inhabitants and competition with newly introduced cattle would have amplified the impacts on megafaunal populations, leading to numerous extinctions in this period.

Modeling drivers’ speed selection as a trade-off behavior

This paper proposes a new model of driver-preferred speeds derived from the assumption that drivers trade-off a portion of their safety for a time gain. The risk of receiving a ticket for speeding is also considered. A trip disutility concept is selected to combine the three components of speed choice (safety, time, and enforcement). The perceived crash risk and speed enforcement are considered as speed deterrents while the perceived value of a time gain is considered as a speed enticement. According to this concept, speeds that minimize the perceived trip disutility are preferred by drivers. The modeled trade-off behavior does not have to be fully rational since it is affected by drivers’ preferences and their ability to perceive the risk. As such, the proposed framework follows the concept of bound rationality. The attractiveness of the model lies in its parameters being estimable with the observed preferred speeds and then interpretable as the factors of risk perception, the subjective value of time, and the perceived risk of speed enforcement. The proposed method may successfully supplement behavioral studies based on a driver survey. The study focuses on four-lane rural and suburban roads in Indiana, USA. The behavior of two types of drivers (trucks and cars) is modeled. The selection of test sites was such that the roads and other local characteristics varied across the studied sites while the population of drivers could be assumed as the same. The density of intersections, land development along the road, and the presence of sidewalks were the identified prominent risk perception factors. Another interesting finding is that the speed limit seems to encourage slow drivers to drive faster and fast drivers to drive slower.