One night CPAP withdrawal impairs performance at a driving simulator task faster than sleep restriction to 5 hours with treatment in OSA patients

Introduction Sleep restriction and missing 1 night’s continuous positive air pressure (CPAP) treatment are scenarios faced by obstructive sleep apnoea (OSA) patients, who must then assess their own fitness to drive. This study aims to assess the impact of this on driving performance. Method 11 CPAP treated participants (50–75 yrs), drove an interactive car simulator under monotonous motorway conditions for 2 hours on 3 afternoons, following;(i)normal night’s sleep (average 8.2 h) with CPAP (ii) sleep restriction (5 h), with CPAP (iii)normal length of sleep, without CPAP. Driving incidents were noted if the car came out of the designated driving lane. EEG was recorded continually and KSS reported every 200 seconds. Results Driving incidents: Incidents were more prevalent following CPAP withdrawal during hour 1, demonstrating a significant condition time interaction [F(6,60) = 3.40, p = 0.006]. KSS: At the start of driving participants felt sleepiest following CPAP withdrawal, by the end of the task KSS levels were similar following CPAP withdrawal and sleep restriction, demonstrating a significant condition, time interaction [F(3.94,39.41) = 3.39, p = 0.018]. EEG: There was a non significant trend for combined alpha and theta activity to be highest throughout the drive following CPAP withdrawal. Discussion CPAP withdrawal impairs driving simulator performance sooner than restricting sleep to 5 h with CPAP. Participants had insight into this increased sleepiness reflected by the higher KSS reported following CPAP withdrawal. In the practical terms of driving any one incident could be fatal. The earlier impairment reported here demonstrates the potential danger of missing CPAP treatment and highlights the benefit of CPAP treatment even when sleep time is short.

Hearing loss and a supportive tactile signal in a navigation system : effects on driving behavior and eye movements

An on-road study was conducted to evaluate a complementary tactile navigation signal on driving behaviour and eye movements for drivers with hearing loss (HL) compared to drivers with normal hearing (NH). 32 participants (16 HL and 16 NH) performed two preprogrammed navigation tasks. In one, participants received only visual information, while the other also included a vibration in the seat to guide them in the correct direction. SMI glasses were used for eye tracking, recording the point of gaze within the scene. Analysis was performed on predefined regions. A questionnaire examined participant's experience of the navigation systems. Hearing loss was associated with lower speed, higher satisfaction with the tactile signal and more glances in the rear view mirror. Additionally, tactile support led to less time spent viewing the navigation display.

Is the two hour recommended maximum driving time appropriate for both healthy older and treated obstructive sleep apnoea drivers?

Objectives The UK Department for Transport recommends taking a break from driving every 2 h. This study investigated: (i) if a 2 h drive time on a monotonous road is appropriate for OSA patients treated with CPAP, compared with healthy age matched controls, (ii) the impact of a night’s sleep restriction (with CPAP) and (iii) what happens if these patients miss one nights’ CPAP treatment. Methods About 19 healthy men aged 52–74 y (m = 66.2 y) and 19 OSA participants aged 50–75 y (m = 64.4 y) drove an interactive car simulator under monotonous motorway conditions for 2 h on two afternoons, in a counterbalanced design; (1) following a normal night’s sleep (8 h). (2) following a restricted night’s sleep (5 h), with normal CPAP use (3) following a night without CPAP treatment. (n = 11) Lane drifting incidents, indicative of falling asleep, were recorded for up to 2 h depending on competence to continue driving. Results Normal sleep: Controls drove for an average of 95.9 min (s.d. 37 min) and treated OSA drivers for 89.6 min (s.d. 29 min) without incident. 63.2% of controls and 42.1% of OSA drivers successfully completed the drive without an incident. Sleep restriction: 47.4% of controls and 26.3% OSA drivers finished without incident. Overall: controls drove for an average of 89.5 min (s.d. 39 min) and treated OSA drivers 65 min (s.d. 42 min) without incident. The effect of condition was significant [F(1.36) = 9.237, P < 0.05, eta2 = 0.204]. Stopping CPAP: 18.2% of drivers successfully completed the drive. Overall, participants drove for an average of 50.1 min (s.d. 38 min) without incident. The effect of condition was significant [F(2) = 8.8, P < 0.05, eta2 = 0.468]. Conclusion 52.6% of all drivers were able to complete a 2 hour drive under monotonous conditions after a full night’s sleep. Sleep restriction significantly affected both control and OSA drivers. We find evidence that treated OSA drivers are more impaired by sleep restriction than healthy control, as they were less able to sustain safely the 2 h drive without incidents. OSA drivers should be aware that non-compliance with CPAP can significantly impair driving performance. It may be appropriate to recommend older drivers take a break from driving every 90 min especially when undertaking a monotonous drive, as was the case here.

Punishment Avoidance and Intentional Risky Driving Behaviour : What are the Implications for ‘Getting Away with it’?

Every motorised jurisdiction mandates legal driving behaviour which facilitates driver mobility and road user safety through explicit road rules that are enforced by regulatory authorities such as the Police. In road safety, traffic law enforcement has been very successfully applied to modify road user behaviour, and increasingly technology is fundamental in detecting illegal road user behaviour. Furthermore, there is also sound evidence that highly visible and/or intensive enforcement programs achieve long-term deterrent effects. To illustrate, in Australia random breath testing has considerably reduced the incidence and prevalence of driving whilst under the influence of alcohol. There is, however, evidence that many road rules continue to be broken, including speeding and using a mobile phone whilst driving, and there are many instances where drivers are not detected or sufficiently sanctioned for these transgressions. Furthermore, there is a growing body of evidence suggesting that experiences of punishment avoidance – that is, successful attempts at avoiding punishment such as drivers talking themselves out of a ticket, or changing driving routes to evade detection –are associated with and predictive of the extent of illegal driving behaviour and future illegal driving intentions. Therefore there is a need to better understand the phenomenon of punishment avoidance to enhance our traffic law enforcement procedures and therefore safety of all road users. This chapter begins with a review of the young driver road safety problem, followed by an examination of contemporary deterrence theory to enhance our understanding of both the experiences and implications of punishment avoidance in the road environment. It is noteworthy that in situations where detection and punishment remain relatively rare, such as on extensive road networks, the research evidence suggests that experiences of punishment avoidance may have a stronger influence upon risky driving behaviour than experiences of punishment. Finally, data from a case study examining the risky behaviour of young drivers will be presented, and the implications for ‘getting away with it’ will be discussed.

Stiffness-damping matching method of an ECAS system based on LQG control

A novel method of matching stiffness and continuous variable damping of an ECAS (electronically controlled air suspension) based on LQG (linear quadratic Gaussian) control was proposed to simultaneously improve the road-friendliness and ride comfort of a two-axle school bus. Taking account of the suspension nonlinearities and target-height-dependent variation in suspension characteristics, a stiffness model of the ECAS mounted on the drive axle of the bus was developed based on thermodynamics and the key parameters were obtained through field tests. By determining the proper range of the target height for the ECAS of the fully-loaded bus based on the design requirements of vehicle body bounce frequency, the control algorithm of the target suspension height (i.e., stiffness) was derived according to driving speed and road roughness. Taking account of the nonlinearities of a continuous variable semi-active damper, the damping force was obtained through the subtraction of the air spring force from the optimum integrated suspension force, which was calculated based on LQG control. Finally, a GA (genetic algorithm)-based matching method between stepped variable damping and stiffness was employed as a benchmark to evaluate the effectiveness of the LQG-based matching method. Simulation results indicate that compared with the GA-based matching method, both dynamic tire force and vehicle body vertical acceleration responses are markedly reduced around the vehicle body bounce frequency employing the LQG-based matching method, with peak values of the dynamic tire force PSD (power spectral density) decreased by 73.6%, 60.8% and 71.9% in the three cases, and corresponding reduction are 71.3%, 59.4% and 68.2% for the vehicle body vertical acceleration. A strong robustness to variation of driving speed and road roughness is also observed for the LQG-based matching method.

Concealed texting while driving : what are young people’s beliefs about this risky behaviour?

Making a conscious effort to hide the fact that one is texting while driving (i.e., concealed texting) is a deliberate and risky behaviour involving attention diverted from the road. As the most frequent users of text messaging services and mobile phones while driving, young people appear at heightened crash risk from engaging in this behaviour. First, several small focus group discussions (N = 12) were carried out to elicit the underlying salient beliefs regarding this behaviour, in accordance with the Theory of Planned Behaviour (TPB). Findings from these discussions, in conjunction with available prior evidence regarding general mobile phone use while driving, then informed questionnaire items that assessed young peoples’ beliefs regarding this behaviour, as well as intention to engage in this behaviour in the next week. In the questionnaire phase of the study, participants (N = 171) were aged 17–25 years, owned a mobile phone, and held a current driver’s licence. Results showed that there were significant differences between low and high intenders (to engage in concealed texting while driving) on the behavioural, normative, and control beliefs investigated. Specifically, high intenders were more likely to believe that concealed texting while driving would result in sharing information with others, using time effectively, and were less likely to think that free-flowing traffic would prevent their engagement in this behaviour. By targeting these beliefs, these findings may potentially inform the development of advertising and other public intervention strategies, aimed at ensuring young drivers reconsider their engagement in this risky behaviour.

Prediction of driving safety in individuals with homonymous hemianopia and quadrantanopia from clinical neuro-imaging

BACKGROUND: The objective of this study was to determine whether it is possible to predict driving safety in individuals with homonymous hemianopia or quadrantanopia based upon a clinical review of neuro-images that are routinely available in clinical practice. METHODS: Two experienced neuro-ophthalmologists viewed a summary report of the CT/MRI scans of 16 participants with homonymous hemianopic or quadrantanopic field defects which provided information regarding the site and extent of the lesion and made predictions regarding whether they would be safe/unsafe to drive. Driving safety was defined using two independent measures: (1) The potential for safe driving was defined based upon whether the participant was rated as having the potential for safe driving, determined through a standardized on-road driving assessment by a certified driving rehabilitation specialist conducted just prior and (2) state recorded motor vehicle crashes (all crashes and at-fault). Driving safety was independently defined at the time of the study by state recorded motor vehicle crashes (all crashes and at-fault) recorded over the previous 5 years, as well as whether the participant was rated as having the potential for safe driving, determined through a standardized on-road driving assessment by a certified driving rehabilitation specialist. RESULTS: The ability to predict driving safety was highly variable regardless of the driving outcome measure, ranging from 31% to 63% (kappa levels ranged from -0.29 to 0.04). The level of agreement between the neuro-ophthalmologists was also only fair (kappa =0.28). CONCLUSIONS: The findings suggest that clinical evaluation of summary reports currently available neuro-images by neuro-ophthalmologists is not predictive of driving safety. Future research should be directed at identifying and/or developing alternative tests or strategies to better enable clinicians to make these predictions.

Sensorimotor and postural control factors associated with driving safety in a community-dwelling older driver population

Background. To establish whether sensorimotor function and balance are associated with on-road driving performance in older adults. Methods. The performance of 270 community-living adults aged 70–88 years recruited via the electoral roll was measured on a battery of peripheral sensation, strength, flexibility, reaction time, and balance tests and on a standardized measure of on-road driving performance. Results. Forty-seven participants (17.4%) were classified as unsafe based on their driving assessment. Unsafe driving was associated with reduced peripheral sensation, lower limb weakness, reduced neck range of motion, slow reaction time, and poor balance in univariate analyses. Multivariate logistic regression analysis identified poor vibration sensitivity, reduced quadriceps strength, and increased sway on a foam surface with eyes closed as significant and independent risk factors for unsafe driving. These variables classified participants into safe and unsafe drivers with a sensitivity of 74% and specificity of 70%. Conclusions. A number of sensorimotor and balance measures were associated with driver safety and the multivariate model comprising measures of sensation, strength, and balance was highly predictive of unsafe driving in this sample. These findings highlight important determinants of driver safety and may assist in developing efficacious driver safety strategies for older drivers.

Visually impaired drivers who use bioptic telescopes : self-assessed driving skills and agreement with on-road driving evaluation

Purpose. To compare self-assessed driving habits and skills of licensed drivers with central visual loss who use bioptic telescopes to those of age-matched normally sighted drivers, and to examine the association between bioptic drivers' impressions of the quality of their driving and ratings by a “backseat” evaluator. Methods. Participants were licensed bioptic drivers (n = 23) and age-matched normally sighted drivers (n = 23). A questionnaire was administered addressing driving difficulty, space, quality, exposure, and, for bioptic drivers, whether the telescope was helpful in on-road situations. Visual acuity and contrast sensitivity were assessed. Information on ocular diagnosis, telescope characteristics, and bioptic driving experience was collected from the medical record or in interview. On-road driving performance in regular traffic conditions was rated independently by two evaluators. Results. Like normally sighted drivers, bioptic drivers reported no or little difficulty in many driving situations (e.g., left turns, rush hour), but reported more difficulty under poor visibility conditions and in unfamiliar areas (P < 0.05). Driving exposure was reduced in bioptic drivers (driving 250 miles per week on average vs. 410 miles per week for normally sighted drivers, P = 0.02), but driving space was similar to that of normally sighted drivers (P = 0.29). All but one bioptic driver used the telescope in at least one driving task, and 56% used the telescope in three or more tasks. Bioptic drivers' judgments about the quality of their driving were very similar to backseat evaluators' ratings. Conclusions. Bioptic drivers show insight into the overall quality of their driving and areas in which they experience driving difficulty. They report using the bioptic telescope while driving, contrary to previous claims that it is primarily used to pass the vision screening test at licensure.

A simulation-based large deflection and inelastic analysis of steel frames under fire

This paper presents an accurate and robust geometric and material nonlinear formulation to predict structural behaviour of unprotected steel members at elevated temperatures. A fire analysis including large displacement effects for frame structures is presented. This finite element formulation of beam-column elements is based on the plastic hinge approach to model the elasto-plastic strain-hardening material behaviour. The Newton-Raphson method allowing for the thermal-time dependent effect was employed for the solution of the non-linear governing equations for large deflection in thermal history. A combined incremental and total formulation for determining member resistance is employed in this nonlinear solution procedure for the efficient modeling of nonlinear effects. Degradation of material strength with increasing temperature is simulated by a set of temperature-stress-strain curves according to both ECCS and BS5950 Part 8, which implicitly allows for creep deformation. The effects of uniform or non-uniform temperature distribution over the section of the structural steel member are also considered. Several numerical and experimental verifications are presented.

Investigating the individual and organisational predictors of work-related driving crash involvement in Ethiopia

The rate of road traffic injury and death in Ethiopia is at a critical level when compared to rates in high-income countries. Considering the enormity of this issue, research is to identify groups of high-risk road users and the factors contributing to their crash involvement. This study focuses on work-related drivers. This study explores driving behaviour as a mediator of the relationship between organisational and individual attribute factors and self-reported crashes in a sample of 213 work-related drivers in Addis Ababa, Ethiopia. The hypothesised framework identifies driving behaviour as the most proximal determinant of self-reported crashes, and safety values, role overload and self-efficacy as antecedents of driving behaviour. With the exception of the relationship between self-efficacy and driving behaviour, all the hypothesised relationships were supported. We make recommendations for intervention approaches that are theoretically focused and sensitive to the cultural context.

Consumer perceptions of medication warnings about driving : a comparison of French and Australian labels

OBJECTIVE Little research has examined user perceptions of medication warnings about driving. Consumer perceptions of the Australian national approach to medication warnings about driving are examined. The Australian approach to warning presentation is compared with an alternative approach used in France. Visual characteristics of the warnings and overall warning readability are investigated. Risk perceptions and behavioral intentions associated with the warnings are also examined. METHOD Surveys were conducted with 358 public hospital outpatients in Queensland, Australia. Extending this investigation is a supplementary comparison study of French hospital outpatients (n = 75). RESULTS The results suggest that the Australian warning approach of using a combination of visual characteristics is important for consumers but that the use of a pictogram could enhance effects. Significantly higher levels of risk perception were found among the sample for the French highest severity label compared to the analogous mandatory Australian warning, with a similar trend evident in the French study results. The results also indicated that the French label was associated with more cautious behavioral intentions. CONCLUSION The results are potentially important for the Australian approach to medication warnings about driving impairment. The research contributes practical findings that can be used to enhance the effectiveness of warnings and develop countermeasures in this area. Hospital pharmacy patients should include persons with the highest level of likelihood of knowledge and awareness of medication warning labeling. Even in this context it appears that a review of the Australian warning system would be useful particularly in the context of increasing evidence relating to associated driving risks. Reviewing text size and readability of messages including the addition of pictograms, as well as clarifying the importance of potential risk in a general community context, is recommended for consideration and further research.

Hospital outpatients' responses to taking medications with driving warnings

OBJECTIVE The study investigates the knowledge, intentions, and driving behavior of persons prescribed medications that display a warning about driving. It also examines their confidence that they can self-assess possible impairment, as is required by the Australian labeling system. METHOD We surveyed 358 outpatients in an Australian public hospital pharmacy, representing a well-advised group taking a range of medications including those displaying a warning label about driving. A brief telephone follow-up survey was conducted with a subgroup of the participants. RESULTS The sample had a median age of 53.2 years and was 53 percent male. Nearly three quarters (73.2%) had taken a potentially impairing class of medication and more than half (56.1%) had taken more than one such medication in the past 12 months. Knowledge of the potentially impairing effects of medication was relatively high for most items; however, participants underestimated the possibility of increased impairment from exceeding the prescribed dose and at commencing treatment. Participants' responses to the safety implications of taking drugs with the highest level of warning varied. Around two thirds (62.8%) indicated that they would consult a health practitioner for advice and around half would modify their driving in some way. However, one fifth (20.9%) would drive when the traffic was thought to be less heavy and over a third (37.7%) would modify their medication regime so that they could drive. The findings from the follow-up survey of a subsample taking target drugs at the time of the first interview were also of concern. Only just over half (51%) recalled seeing the warning label on their medications and, of this group, three quarters (78%) reported following the warning label advice. These findings indicated that there remains a large proportion of people who either did not notice or did not consider the warning when deciding whether to drive. There was a very high level of confidence in this group that they could determine whether they were personally affected by the medication, which may be a problem from a safety perspective. CONCLUSION This study involved persons who should have had a very high level of knowledge and awareness of medication warning labeling. Even in this group there was a lack of informed response to potential impairment. A review of the Australian warning system and wider dissemination of information on medication treatment effects would be useful. Clarifying the importance of potential risk in the general community context is recommended for consideration and further research.

Blast response of reinforced concrete pile using fully coupled computer simulation techniques

Pile foundations transfer loads from superstructures to stronger sub soil. Their strength and stability can hence affect structural safety. This paper treats the response of reinforced concrete pile in saturated sand to a buried explosion. Fully coupled computer simulation techniques are used together with five different material models. Influence of reinforcement on pile response is investigated and important safety parameters of horizontal deformations and tensile stresses in the pile are evaluated. Results indicate that adequate longitudinal reinforcement and proper detailing of transverse reinforcement can reduce pile damage. Present findings can serve as a benchmark reference for future analysis and design.

Process modelling and simulation of tissue damage during mechanical peeling of pumpkin as a tough skinned vegetable

Food waste is a current challenge that both developing and developed countries face. This project applied a novel combination of available methods in Mechanical, agricultural and food engineering to address these challenges. A systematic approach was devised to investigate possibilities of reducing food waste and increasing the efficiency of industry by applying engineering concepts and theories including experimental, mathematical and computational modelling methods. This study highlights the impact of comprehensive understanding of agricultural and food material response to the mechanical operations and its direct relation to the volume of food wasted globally.