Impact of speed change on estimated journey time: failure of drivers to appreciate relevance of initial speed

Evaluating the effects of a simulator-based training on knowledge, attitudes and driving profiles of German ambulance drivers

INTRODUCTION

Accident risk is increased for emergency responders driving with warning lights and sirens compared to other road users' driving. Currently no standards for education of ambulance drivers exist. Research shows that high order understanding trainings focusing on insight to avoid critical driving situations might be more helpful than trainings focusing on car handling. The present controlled intervention study evaluates a one-day simulator-based high order training program specifically designed for ambulance drivers.

METHODS

In a longitudinal design with three measurement times multiple methods were used to evaluate the training holistically targeting the levels of reaction to training, learning, behavior and results of training. Questionnaire, knowledge test and driving profile data were analyzed with repeated measures analysis of variance controlling for age and sex. Data of two intervention groups and one control-waiting group was collected between 2014 and 2017 in two German federal states.

RESULTS

183 German paramedics (age: M = 33.1, SD = 9.4, 21.9 % female) participated in the study. 147 participants (80.3 %) completed post-training tests, and 30 participants (16.4 %) completed follow-up measurements six months after training. Participants' reaction to training was positive directly after the training, and dropped slightly over time. Intervention group participants gained traffic-relevant knowledge compared to control group participants. Risk sensitivity of regular driving situations was the only attitude variable positively affected by training. This effect was not sustained six months after training. Training led to a decrease of average and maximum speed in short- as well as long-term measurements but did not affect drivers' acceleration. Although speed was lower in post-tests, emergency response times did not differ.

CONCLUSION

The simulator-based training for paramedics has small but notable effects on drivers' knowledge, attitudes and real driving behavior. Although only very few measured variables showed positive training effects, no negative training effects were found. Speed was reduced in the long term which underlines the importance of such a training. More research is needed to determine effects on different types of participants and to elicit framework conditions for training integration in formal education.

Modelling braking behaviour and accident probability of drivers under increasing time pressure conditions

Drivers apply brakes to reduce the speed of a vehicle based on the perceived risk while approaching a certain event. Inadequate or excessive braking can lead to serious consequences. The current study analyses the braking behaviour and accident probability of the drivers under increasing time pressure conditions. Two perilous events (pedestrian crossing and obstacle overtaking) were designed to examine Brake Pedal Force (BPF) and Brake-To-Maximum Brake (BTMB) transition time on a driving simulator. Eighty-five Indian licensed drivers drove the simulator in three different time pressure conditions: No Time Pressure (NTP) (baseline), Low Time Pressure (LTP), and High Time Pressure (HTP). Random parameters Tobit model was used for analysing BPF and duration analysis approach was considered for BTMB analysis. Further, generalized linear mixed model with logit link function was used to study the effect of BPF and BTMB on accident probability of the drivers. The model results showed that gender, driving profession, approach speed, age, driving history, and driving condition significantly affected braking behaviour of the drivers. It was observed that in pedestrian crossing event, LTP and HTP driving conditions resulted in 42.31 % and 87.28 % increase in BPF and 13 % and 23 % reduction in BTMB respectively with respect to NTP driving condition and the corresponding changes were slightly lower in case of obstacle overtaking event. The accident probability model showed that female drivers needed 119.70 % and 186.08 % more BPF and 37.55 % and 58.51 % less BTMB in LTP and HTP driving conditions respectively to have equivalent risk levels as observed for male drivers. Further, non-professional drivers had to increase their BPF by 166.83 % in LTP and 219.93 % in HTP to offset their increased accident risk as compared to professional drivers under time pressure conditions.

Reducing the time loss bias: Two ways to improved driving safety and energy efficiency

The time loss bias describes the systematic overestimation of time lost when decelerating from a relatively high speed. In the present study, we investigated the debiasing effect of two educational interventions, the Paceometer (Peer and Gamliel, 2013) and a newly designed Pop-up assistant, in a video-based controlled-access highway driving scenario. The Paceometer provides participants with pace information (min/km) added to the common speedometer. The Pop-up assistant informs about the time lost when decreasing speed according to a specific situation. A mixed-design ANOVA confirmed the improvement of time loss estimations for both debiasing tools and the superiority of the Pop-up assistant, which produced temporal spillover effects. We discuss potential explanations in terms of simplifying information and anchoring and the potential benefits of both tools to reduce risky driving, fuel costs and range restrictions of electric vehicles.

A Surrogate Video-Based Safety Methodology for Diagnosis and Evaluation of Low-Cost Pedestrian-Safety Countermeasures: The Case of Cochabamba, Bolivia

Due to a lack of reliable data collection systems, traffic fatalities and injuries are often under-reported in developing countries. Recent developments in surrogate road safety methods and video analytics tools offer an alternative approach that can be both lower cost and more time efficient when crash data is incomplete or missing. However, very few studies investigating pedestrian road safety in developing countries using these approaches exist. This research uses an automated video analytics tool to develop and analyze surrogate traffic safety measures and to evaluate the effectiveness of temporary low-cost countermeasures at selected pedestrian crossings at risky intersections in the city of Cochabamba, Bolivia. Specialized computer vision software is used to process hundreds of hours of video data and generate data on road users’ speed and trajectories. We find that motorcycles, turning movements, and roundabouts, are among the key factors related to pedestrian crash risk, and that the implemented treatments were effective at four-legged intersections but not at traditional-design roundabouts. This study demonstrates the applicability of the surrogate methodology based on automated video analytics in the Latin American context, where traditional methods are challenging to implement. The methodology could serve as a tool to rapidly evaluate temporary treatments before they are permanently implemented and replicated.

The use of a driving simulator to determine how time pressures impact driver aggressiveness

Speeding greatly attributes to traffic safety with approximately a third of fatal crashes in the United States being speeding-related. Previous research has identified being late as a primary cause of speeding. In this driving simulator study, a virtual drive was constructed to evaluate how time pressures, or hurried driving, affected driver speed choice and driver behavior. In particular, acceleration profiles, gap acceptance, willingness to pass, and dilemma zone behavior were used, in addition to speed, as measures to evaluate whether being late increased risky and aggressive driving behaviors. Thirty-six drivers were recruited with an equal male/female split and a broad distribution of ages. Financial incentives and completion time goals calibrated from a control group were used to generate a Hurried and Very Hurried experimental group. As compared to the control group, Very Hurried drivers selected higher speeds, accelerated faster after red lights, accepted smaller gaps on left turns, were more likely to pass a slow vehicle, and were more likely to run a yellow light in a dilemma zone situation. These trends were statistically significant and were also evident with the Hurried group but a larger sample would be needed to show statistical significance. The findings from this study provide evidence that hurried drivers select higher speeds and exhibit riskier driving behaviors. These conclusive results have possible implications in areas such as transportation funding and commercial motor vehicle safety.

Estimation of the population attributable fraction of road-related injuries due to speeding and passing in Iran

OBJECTIVES

Speeding and passing are considered to be the main human factors resulting in road traffic injuries (RTIs). This study aimed to estimate the population attributeable fraction (PAF) of speeding and passing in RTIs in rural Iran during 2012.

METHODS

The contribution of speeding and passing to RTI-related morbidity and mortality was estimated using the PAF method. The prevalence of speeding and passing was obtained from the national traffic police data registry. A logistic regression model was used to measure the association between the above risk factors and RTIs.

RESULTS

Speeding accounted for 20.96% and 16.61% of rural road-related deaths and injuries, respectively. The corresponding values for passing were 13.50% and 13.44%, respectively. Jointly, the PAF of these factors was 31.63% for road-related deaths and 27.81% for injuries.

CONCLUSIONS

This study illustrates the importance of controlling speeding and passing as a high-priority aspect of public-health approaches to RTIs in Iran. It is recommended that laws restricting speeding and passing be enforced more strictly.

Speeding in urban environments: Are the time savings worth the risk?

Perceived time savings by travelling faster is often cited as a motivation for drivers' speeding behaviour. These time savings, however, come at a cost of significant road injuries and fatalities. While it is known that drivers tend to overestimate the time savings attributable to speeding there is little empirical evidence on how much time drivers genuinely save during day-to-day urban driving and how this relates to speeding-related crashes. The current paper reports on a study to address the lack of empirical evidence on this issue using naturalistic driving data collected from 106 drivers over a period of five weeks. The results show that the average driver saves 26s/day or 2min/week by speeding. More importantly, the cost of these time savings is one fatality for every 24,450h saved by the population on 100km/h roads in dry conditions and one injury for every 2458h saved on the same roads. Full speed compliance - and consequently a dramatic reduction in the road toll - could be achieved through almost imperceptible increases in travel time by each driver.

Estimated time of arrival and debiasing the time saving bias

The time saving bias predicts that the time saved when increasing speed from a high speed is overestimated, and underestimated when increasing speed from a slow speed. In a questionnaire, time saving judgements were investigated when information of estimated time to arrival was provided. In an active driving task, an alternative meter indicating the inverted speed was used to debias judgements. The simulated task was to first drive a distance at a given speed, and then drive the same distance again at the speed the driver judged was required to gain exactly 3 min in travel time compared with the first drive. A control group performed the same task with a speedometer and saved less than the targeted 3 min when increasing speed from a high speed, and more than 3 min when increasing from a low speed. Participants in the alternative meter condition were closer to the target. The two studies corroborate a time saving bias and show that biased intuitive judgements can be debiased by displaying the inverted speed. Practitioner Summary: Previous studies have shown a cognitive bias in judgements of the time saved by increasing speed. This simulator study aims to improve driver judgements by introducing a speedometer indicating the inverted speed in active driving. The results show that the bias can be reduced by presenting the inverted speed and this finding can be used when designing in-car information systems.

Modeling and debiasing resource saving judgments

Svenson (2011) showed that choices of one of two alternative productivity increases to save production resources (e.g., man-months) were biased. Judgments of resource savings following a speed increase from a low production speed line were underestimated and following an increase of a high production speed line overestimated. The objective formula for computing savings includes differences between inverse speeds and this is intuitively very problematic for most people. The purpose of the present studies was to explore ways of ameliorating or eliminating the bias. Study 1 was a control study asking participants to increase the production speed of one production line to save the same amount of production resources (man-months) as was saved by a speed increase in a reference line. The increases judged to match the reference alternatives showed the same bias as in the earlier research on choices. In Study 2 the same task and problems were used as in Study 1, but the participants were asked first to judge the resource saving of the reference alternative in a pair of alternatives before they proceeded to the matching task. This weakened the average bias only slightly. In Study 3, the participants were asked to judge the resources saved from each of two successive increases of the same single production line (other than those of the matching task) before they continued to the matching problems. In this way a participant could realize that a second production speed increase from a higher speed (e.g., from 40 to 60 items /man-month) gives less resource savings than the same speed increase from a first lower speed (e.g., from 20 to 40 items/man-month. Following this, the judgments of the same problems as in the other studies improved and the bias decreased significantly but it did not disappear. To be able to make optimal decisions about productivity increases, people need information about the bias and/or reformulations of the problems.

Prevalence, knowledge, attitude and practice of speeding in two districts in Kenya: Thika and Naivasha

INTRODUCTION

In Kenya, RTIs had the second highest increase in disability-adjusted life years between 1990 and 2010, compared to other conditions. This study aims to determine the prevalence, knowledge, attitudes and practices for speeding in Thika and Naivasha districts in Kenya.

METHODS

Direct observations of vehicle speed were conducted at various times during the day and different days of the week on six roads selected based on a multi-stage sampling method in two districts to determine the prevalence of speeding. Roadside KAP interviews were administered to drivers, at motorcycle bays, petrol stations, and rest areas.

RESULTS

Eight rounds of speed observations and four rounds of KAP interviews were conducted between July 2010 and November 2012. Results from the speeding observational studies show an overall high proportion of vehicles speeding above posted limits in both districts, with an average of 46.8% in Thika and 40.2% in Naivasha. Trend analysis revealed a greater decline in this prevalence in Thika (OR: 0.804, 95% CI: 0.793-0.814) than in Naivasha (OR: 0.932, 95% CI: 0.919-0.945) over the study period. On average, 58.8% of speeding vehicles in Thika and 57.2% of speeding vehicles in Naivasha travelled at 10 km/h or higher above speed limit. While the majority of respondents agreed that speeding is a cause of road traffic crashes in both Thika (70.3%) and Naivasha (68.7%), knowledge of speed limits at the location of the interview was limited. Enforcement levels also remained low, but subsequent rounds of data collection showed improvement, especially in Thika.

CONCLUSIONS

This study demonstrates an improvement in the prevalence of speeding in two districts of Kenya over 2010-2012. It also highlights the need for further action to be taken to address the problem, and represents new data on speeding in Kenya and Africa.

The time-saving bias: Judgements, cognition and perception

Biases in people’s judgments of time saved by increasing the speed of an activity have been studied mainly with hypothetical scenarios (Svenson, 2008). The present study asked whether the classic time-saving bias persists as a perceptual bias when we control the speed of an activity and assess the perceived time elapsed at different speeds. Specifically, we investigated the time-saving bias in a driving simulator. Each participant was asked to first drive a distance at a given speed and then drive the same distance again at the speed she or he judged necessary to gain exactly three minutes in travel time compared to the first trip. We found that that the time-saving bias applies to active driving and that it affects the choice of driving speed. The drivers’ time-saving judgements show that the perception of the time elapsed while driving does not eliminate the time-saving bias.

How do time pressured drivers estimate speed and time?

The purpose of this laboratory study was to investigate the influence of time pressure on the perception of speed and duration in driving situations. Participants provided estimations of speed and performed both productions and reproductions of time durations, based on traffic films. The experimental films were made from a driver's point of view within a moving car, and audio-recorded instructions invited participants to imagine that they were driving while under time pressure or while relaxed. The results obtained using this within-participant design support the hypothesis that time pressure promotes fast driving, and may induce an underestimation of speed and trip-related durations, the latter of which suggests that time pressure modulates time perception. Some of these effects were mediated by the emotional impact of time pressure. Links between time perception and speed were also observed. The discussion makes reference to internal clock models and focuses on the practical consequences of these results.

Pace yourself: Improving time-saving judgments when increasing activity speed

The time-saving bias describes people’s tendency to misestimate the time they can save by increasing the speed in which they perform an activity such as driving or completing a task. People typically underestimate time saved when increasing from a low speed and overestimate time saved when increasing from an already high speed. We suggest that this bias is the result of people’s failure to recognize the curvilinear relationship between increasing speed and reducing activity time: As initial speed rises, the same speed increases will yield smaller reductions in time. We explore a new technique to de-bias these faulty estimations: converting measurements of speed to a pace measure (e.g., minutes per fixed distance). Utilizing common driving scenarios, we show that participants who received pace data made more accurate estimations of journey duration at various speeds, time-savings at various speed increases and the required speed to complete a journey.

When two motivations race: The effects of time-saving bias and sensation-seeking on driving speed choices

Time-saving bias-people's biased judgments in estimating the time saved when increasing speed-has been found to strongly impact driving speed choices. However, this bias may be relevant only when the driver's motivation for increasing speed is to arrive sooner. If, on the other hand, the driver is motivated by the desire to experience thrill and sensation, a driver's level of sensation-seeking might better explain choices of speed. In this study, participants were asked to estimate the journey time when increasing speed and to estimate the speed required to arrive on time. They also indicated the speed they would personally choose in such a situation. Next, participants filled out Zuckerman's (1994) Sensation Seeking Scale. Results showed that both time-saving estimations and the Disinhibition scale of Sensation Seeking (as well as drivers' gender) contributed independently and additively to drivers' choice of speed and that time-saving bias' role was somewhat stronger than sensation-seeking.

Estimating time savings: the use of the proportion and percentage heuristics and the role of need for cognition

People generally overestimate the time they can save when increasing from a relatively high driving speed. Previous research suggested that people follow a Proportion Heuristic, calculating the time saved as the proportion of speed increase from the new higher speed. The present study suggests that drivers use another heuristic - the Percentage Heuristic - to calculate how much time they save by increasing speed. In the percentage heuristic, the initial (rather than higher) speed is used as the denominator. Using a discriminating set of questions, we classified participants' responses as normative (correct answer), as following the proportion or percentage heuristic, or some other strategy. We found that participants used the percentage heuristic more often, perhaps because it predicts linearly increasing values of time saved when increasing speed. In addition, we found that participants high in need for cognition (NFC) gave correct answers more often than low NFC participants who relied more on heuristics.

Using a multidimensional Rasch model approach to measure the police's perceived ability to detect, detain and intercept DWI vehicles when conducting sobriety checkpoints

This study developed a scale to measure 502 Taiwan traffic police officers' perceived ability to detect, detain, and intercept those vehicles whose drivers are driving while intoxicated (DWI) when conducting sobriety checkpoints. Through factor analysis, the officers' enforcement ability was found to consist of two component latent traits: detecting ability (DA) and detaining and intercepting ability (DIA). A multidimensional approach of Rasch models was then applied to measure the police officers' perceived abilities and particular difficulties in conducting sobriety checkpoints. The study results indicated that the majority of police officers performed well in detecting DWI vehicles, but half of the study participants lacked confidence in detaining DWI vehicles and intercepting escaping DWI vehicles. DWI with weaving was found to be the most aggressive and threatening behavior to traffic police when conducting sobriety checkpoints. Police officers over age 46 were found to have significantly lower DA and DIA, while branch captains were found to have significantly higher DA than their colleagues. Several strategies and programs are suggested based on the study findings to improve the enforcement ability of police officers.

Professionally biased: Misestimations of driving speed, journey time and time-savings among taxi and car drivers

People make systematic and predictable mistakes regarding estimations of average speed and journey time. In addition, people have been shown to commit a time-saving bias by underestimating the time that can be saved when increasing from a low speed and overestimating the time that can be saved when increasing from a relatively high speed. These misestimations have been shown to relate to biases in judgments of the speed required to arrive at a specific time and to choosing unduly high speed. Professional drivers, such as taxi drivers, might be less susceptible to these biases due to their increased driving experience. In the current study, we interviewed taxi drivers about a journey they were currently making and examined their estimations of journey time, average speed and time savings. Compared to a group of non-professional car drivers, taxi drivers showed the same considerable misestimations of driving speed, journey time and time savings as non-professionals. However, overestimations of time savings among taxi drivers were smaller than those made by car drivers. We discuss the practical significance of these findings.

Ship collision risk assessment for the Singapore Strait

The Singapore Strait is considered as the bottleneck and chokepoint of the shipping routes connecting the Indian and the Pacific Ocean. Therefore, the ship collision risk assessment is of significant importance for ships passing through the narrow, shallow, and busy waterway. In this paper, three ship collision risk indices are initially proposed to quantitatively assess the ship collision risks in the Strait: index of speed dispersion, degree of acceleration and deceleration, and number of fuzzy ship domain overlaps. These three risk indices for the Singapore Strait are estimated by using the real-time ship locations and sailing speeds provide by Lloyd's MIU automatic identification system (AIS). Based on estimation of these three risk indices, it can be concluded that Legs 4W, 5W, 11E, and 12E are the most risky legs in the Strait. Therefore, the ship collision risk reduction solutions should be prioritized being implemented in these four legs. This study also finds that around 25% of the vessels sail with a speed in excess of the speed limit, which results in higher potentials of ship collision. Analysis indicates that the safety level would be significantly improved if all the vessels follow the passage guidelines.

Exploring the time-saving bias: How drivers misestimate time saved when increasing speed

According to the time-saving bias, drivers underestimate the time saved when increasing from a low speed and overestimate the time saved when increasing from a relatively high speed. Previous research used a specific type of task — drivers were asked to estimate time saved when increasing speed and to give a numeric response — to show this. The present research conducted two studies with multiple questions to show that the time-saving bias occurs in other tasks. Study 1 found that drivers committed the time-saving bias when asked to estimate (a) the time saved when increasing speed or (b) the distance that can be completed at a given time when increasing speed or (c) the speed required to complete a given distance in decreasing times. Study 2 showed no major differences in estimations of time saved compared to estimations of the remaining journey time and also between responses given on a numeric scale versus a visual analog scale. Study 3 tested two possible explanations for the time-saving bias: a Proportion heuristic and a Differences heuristic. Some evidence was found for use of the latter.

Speeding and the time-saving bias: how drivers' estimations of time saved in higher speed affects their choice of speed

According to the time-saving bias, drivers overestimate the time saved when increasing from an already relatively high speed and underestimate the time saved when increasing from a relatively low speed. This study examined the effect the time-saving bias may have on drivers' choice of speed using hypothetical situations. Drivers were presented with a situation involving acceleration from a relatively low speed in order to arrive at a destination on time and were asked to estimate the time that could be saved by increasing to higher speeds. Drivers also estimated the speed required for arriving on time, the speed they would personally choose and the speed they believed other drivers would opt for in such a situation. Results showed that drivers indeed underestimated the time that could be saved by increasing from a low speed. In addition, drivers who showed a high time-saving bias (above median) indicated notably higher speeds in all three categories above and their indicated speeds exceeded the speed limit more frequently. These findings suggest that the time-saving bias may help explain why drivers, in some situations, prefer an overly high speed and violate the legal speed limit.