Clothing Configurations Research Articles

Improving Pedestrian Conspicuity at Night: Testing the Efficacy of an Educational Intervention

Most pedestrian fatalities happen at night, and poor conspicuity has been identified as a critical problem. Researchers understand what typical pedestrians do not: At night, a pedestrian’s conspicuity heavily depends on contrast and the presence or absence of retroreflective markings and biological motion. This experiment aims to evaluate the impact of an 11-min educational video that explains these critical concepts. Half of the participants will view the video while the other half will not. All participants will provide quantitative estimates of the nighttime conspicuity and safety of a pedestrian wearing each of five clothing configurations. We hypothesize that participants who view the video will exhibit improved comprehension of safety-relevant concepts and the visual challenges experienced by drivers at night. This research could underscore the value of online interventions in educating road users about critical concepts that impact nighttime conspicuity, thereby encouraging them to adopt evidence-based methods to enhance their conspicuity.

Tradespace Assessment: Thermal Strain Modeling Comparison of Multiple Clothing Configurations Based on Different Environmental Conditions <br>

Tradespace Assessment: Thermal Strain Modeling Comparison of Multiple Clothing Configurations Based on Different Environmental Conditions <br>

Increasing the conspicuity of cyclists at night by using bicycle lights and clothing to highlight their biological motion to oncoming drivers

Reduced conspicuity is an important contributing factor to increased motor vehicle-bicycle crashes and cyclist fatalities at night. This study explored ways of making night-time cyclists more conspicuous to oncoming vehicles through cyclist clothing options and bicycle light position. Fifteen young participants (M = 29.1 ± 4.5 years) drove a closed-road at night and indicated when they first recognized a cyclist pedalling in place at the roadside, facing the approaching vehicle. The bicycle had a static forward-facing white light located either on the handlebars or the helmet and wore one of five clothing configurations: fluorescent vest, retroreflective vest, retroreflective ankle strips, retroreflective vest plus retroreflective ankle strips, retroreflective vest plus biomotion retroreflective strips. There was a significant effect of light position (p < 0.001) and clothing (p < 0.001), where recognition distances were longer when the light was helmet-mounted and when retroreflective strips were worn on the lower legs to highlight the cyclist’s biological motion compared to either of the vest conditions. There was also a significant interaction between light position and clothing (p = 0.007) such that the benefit of retroreflective strips was greater when the bicycle light was helmet-mounted rather than on the handlebars. Importantly, the benefits of leg markings were apparent even when positioned at the ankles alone. These findings highlight that retroreflective material is most useful for improving cyclist conspicuity at night when positioned on cyclists’ lower legs, particularly the ankles (highlighting the cyclist's pedalling motion), rather than on the torso, and have important practical implications for maximising cyclists’ conspicuity and hence safety on night-time roads.

Numerical investigation of the effect of clothing air gap distribution and environmental air speed on dry heat transfer underneath clothing

With a great advantage of presenting physical phenomenon in a three-dimensional vision, the technology of computational fluid dynamics was utilized in the current study for simulating and revealing heat transfer in the air gap/layer between human body and clothing. Five clothing configurations including one with realistic heterogeneous air layer and four simplified ones with homogeneous air layers with air gap thickness (AGT) varying between 4 and 16.34 mm were built. All clothing configurations were simulated under environmental air speeds of 0.2–2.5 m/s. It was found the thermal plume, airflow through clothing openings and pathway at armhole have resulted in an uneven distribution of heat transfer underneath clothing, even for clothing with homogeneous air layers. Simply averaging AGT blurs the heterogeneity of heat transfer over the whole body. The threshold of AGT for arising free convection in the air gap is within 12–16.34 mm at the air speed of 0.2 m/s and 8–12 mm at 2.5 m/s, indicating a substantial influence of environmental airflow on thermal flow in the air gap. Besides, increase of air speed would enhance local heat exchange by entering the air gap through clothing openings, except at the arms, where the heat flux fluctuates due to the direction of airflow in sleeves changing from upwards to downwards. Results of the current study have offered a comprehensive insight into the heat transfer in the air gap and can contribute to improving the accuracy of analytical human – clothing – environment models in clothing thermal engineering.

Influence of Personal Protective Equipment on Wildland Firefighters' Physiological Response and Performance during the Pack Test.

The Pack Test (PT) is a widely used test to establish readiness for work in wildland firefighting. It is common to perform this test dressed in regular exercise clothing. However, wildland firefighters (WFF) have to wear personal protective equipment (PPE) during their deployments, which increases the physiological strain and reduces their work capacity. This study aimed to analyse the impact of full PPE on PT performance. Nine male professional WFF performed in random order a PT walking at the fastest possible self-pace wearing two different clothing configurations: (i) traditional short sports gear (SG) and (ii) the PPE currently used by Spanish WFF. Heart rate (HR), rating of perceived exertion and lap time were recorded during the PT. In addition, oxygen uptake (VO2) was estimated through the individual VO2–HR relationship previously obtained during a graded exercise test. There was a significant decrease in the PT performance (i.e., completion time) (~12%, p < 0.05) in PPE. The physiological demands with this configuration were significantly higher (~10%, p < 0.05). WFF spent ~13 min above the anaerobic threshold in PPE vs. ~4 min in SG. A multiple stepwise regression analysis revealed that PT performance variation might be explained by the maximal aerobic velocity (84.5%) in PPE and the VO2max (75.9%) in SG. In conclusion, wearing complete PPE increases WFF’s physiological strain, which translates into a significant PT performance reduction. Performing the test walking at the fastest possible self-pace wearing the PPE would better reflect the high-intensity effort periods reported in real scenarios.

Using retro-reflective cloth to enhance drivers’ judgment of pedestrian walking direction at night-time

Purpose: Fatal pedestrian collisions are over-represented at night and poor conspicuity is believed to be a leading causative factor. Retro-reflective clothing enhances pedestrian conspicuity, particularly when placed in a biological motion or “biomotion” configuration. In this study, we explored how various retro-reflective clothing configurations affected the ability to judge the direction of a pedestrian walking across the road, which has important implications for collision avoidance. Methods: Participants included 21 young drivers (mean age 21.6 ± 2.0 years) with normal vision. A closed-road circuit was used to assess the accuracy of drivers’ judgement of the direction of walking of a pedestrian at night-time wearing one of five different clothing configurations: four with retro-reflective materials placed in different locations (Biomotion, Legs + Torso, Torso Only, Legs Only), and a control wearing only black clothing (Street). Participants were seated in a stationary vehicle with low beam headlamps, 135 m from a pedestrian, who walked across the road from both sides, in different directions (towards the car, straight across the road, or away from the car). Outcome measures included drivers’ response accuracy and confidence ratings for judging pedestrian walking direction. Results: Accuracy in judging pedestrian walking direction differed significantly across the clothing configurations (p < 0.001). Response accuracy was significantly higher for the Biomotion configuration (80% correct), compared to the other retro-reflective (Legs + Torso 64%; Torso Only 53%; Legs Only 50%) and Street configurations (33%). Similar trends were noted for confidence ratings across the clothing conditions, yet the relationship between confidence ratings and response accuracy within each clothing configurations was poor. Conclusions: The use of retro-reflective clothing in a biomotion configuration facilitated the highest accuracy and confidence in drivers’ judgment of pedestrian walking direction, compared to other configurations. These findings highlight the importance of using biomotion clothing for pedestrians at night, to not only facilitate drivers’ earlier recognition of pedestrians, but also increase their accuracy in determining the walking direction of pedestrians as they cross the road. Practical applications: The use of clothing incorporating retro-reflective material in a biomotion configuration for pedestrians crossing roads at night provides enhanced cues for drivers regarding the presence and walking direction of pedestrians.

Measuring the efficacy of positioning aids for capturing 3D data in different clothing configurations and postures with a high-resolution whole-body scanner

Numerous surveys have been conducted worldwide to capture 3D anthropometric data of individuals scanned in tight underwear. However, such semi-nude data are inadequate for designing workspaces for specialised user populations who wear protective clothing and equipment. Determining the offset between semi-nude and clothed configurations requires the same individual to be repeatedly scanned in exactly the same posture. Specifically, for the use in a high-resolution 3D body scanner, positioning aids for the standing and seated posture were developed to stabilise the posture during the scanning process without compromising data integrity. The mean absolute variability (MAV) index was introduced to determine the efficacy of the positioning aids. It was shown that the positioning aids efficiently reduce the variability in fore-and-aft and side-to-side directions. This way the precondition was created for the precise superimposition of scans permitting the offset between diverse clothing configurations to be determined.

Highlighting Bicyclist Biological Motion Enhances Their Conspicuity in Daylight

For safety purposes, it is critical that bicyclists be conspicuous to drivers. We report two experiments that investigated the benefits of bicycle taillights and fluorescent clothing for enhancing the bicyclist’s rear conspicuity in daylight. In Experiment 1, 24 participants sat in a car parked on a closed road at each of three distances and rated the conspicuity of four bicyclists displaying taillights that varied in their placement, intensity, and mode. The results confirmed that bicycle taillights can significantly enhance conspicuity in daylight. Varying the placement of the taillights revealed that having an “always on” taillight mounted to each of the rider’s ankles was the most conspicuous location to mount taillights, and this effect was particularly strong at greater viewing distances. For seat post-mounted taillights, flashing taillights were rated as more conspicuous. In Experiment 2, 186 participants were passengers on a short drive during which they pressed a button each time they recognized that a bicyclist was present. Each participant passed a test bicyclist wearing one of four clothing configurations. When the cyclist wore a fluorescent yellow jersey paired with fluorescent yellow leg covers, participants responded from a distance that was 3.3 times greater than when the cyclist wore the same jersey without the yellow leg covers. Both of these experiments demonstrate that highlighting bicyclists’ pedaling motion enhances their conspicuity when viewed from behind. These results further emphasize the conspicuity benefits of biological motion and provide bicyclists with techniques to enhance their own conspicuity in daylight.

Fractional Contribution of Wildland Firefighters' Personal Protective Equipment on Physiological Strain.

Activities performed by wildland firefighters are carried out wearing a personal protective equipment (PPE). Although the PPE protects workers from a wide variety of hazards, it may increase their physiological response and limit their performance. The aim of this study was to analyze the effect of the protective clothing (PPC) and the rest of the PPE elements (i.e., helmet, neck shroud, gloves, goggles, and mid-calf leather boots) on the wildland firefighters’ thermophysiological response during a moderate-intense exercise. Six male wildland firefighters performed, in a counterbalanced order, a 120 min graded exercise test wearing three different clothing configurations: (i) a traditional short sports gear (SG), (ii) a PPC, and (iii) a complete firefighters’ PPE. Trials were conducted on separate days at the same time of the day (12:00–15:00 h) and under climate-controlled conditions (∼30°C and ∼30% relative humidity). Heart rate, respiratory gas exchange, gastrointestinal and skin temperature, blood lactate concentration were recorded throughout the tests. Additionally, parameters of heat balance were estimated. Exercise time was shorter (p < 0.001) wearing the PPE (62.4 ± 13.3 min) than with the PPC (115.5 ± 5.0 min) and SG (118.2 ± 20.7 min). The increment of gastrointestinal temperature with the PPE (1.8 ± 0.3°C) was greater (p < 0.05) than the observed in PPC (1.2 ± 0.6°C) and SG (1.0 ± 0.2°C). The use of PPC increased (p < 0.05) subjects’ metabolic demand and skin temperature versus SG during the last 20 min of the test. The sweat retention in the PPE (1,045.7 ± 214.7 g) and PPC (978.3 ± 330.6 g) was significantly higher than that obtained in the SG (510.0 ± 210.0 g). Sweat efficiency decreased (p < 0.05) in the following order: PPE (45.6 ± 18.3%), PPC (64.3 ± 7.8%), and SG (79.3 ± 7.0%). These results highlight the importance of the PPE elements in the subjects’ thermal strain. The reduction in the sweat evaporation produced by the PPE, together with the ensemble mass caused a substantial increase in the subjects’ thermophysiological response. As a consequence the performance was reduced by ∼50%.

Development of a positioning aid to reduce postural variability and errors in 3D whole body scan measurements

Three-dimensional (3D) body scanners have the potential to evaluate changes to the human form through different clothing configurations, the use of protective equipment, or the effects of medical interventions. To achieve this, scans of an individual need to be superimposed for each experimental condition. The literature highlights that one of the limiting factors is postural variability. This paper describes a newly developed ‘positioning aid’ that stabilises the posture during the scanning process and is invisible on scans. The results of a study evaluating the efficacy of the positioning aid showed that it reduces postural variability for all body parts in lateral and longitudinal directions. A reference test with a rigid mannequin indicated that the ‘technical’ variability due to the scanner hardware and software significantly contributes to the residual variability. Furthermore, the study showed that the newly developed positioning aid overall increased the precision of the software-assisted extraction of body dimensions.

An Open-Road Study of the Daytime Conspicuity Benefits of Fluorescent Bicyclist Apparel (Extended Abstract)

According to a 2016 NHTSA report (National Center for Statistics and Analysis, 2016) approximately 50,000 bicyclist injuries and 729 bicyclist fatalities were reported in the United States in the year 2014, with most crashes between motor vehicles and bicycles occuring during daylight hours. Most collisions between motor vehicles and bicyclists involve the bicyclist being struck from behind (Hutchinson &amp; Lindsay, 2009; Kim, Kim, Ulfarsson, &amp; Porrello, 2007). For this reason, it is important that bicyclists be sufficiently conspicuous to drivers who are approaching from behind. There has been a recent surge in research that applies basic perceptual science to make vulnerable road users more easily noticed by drivers. For example, humans’ perceptual sensitivity to biological motion (or “biomotion”; Johansson, 1973) can be used to enhance the conspicuity of pedestrians at night (for a review, see Tyrrell, Wood, Owens, Whetsel-Borzendowski, &amp; Stafford-Sewall, 2016). Similar findings, using either retroreflective tape or LEDs, have been found to apply to cyclists’ conspicuity as well (e.g., Kwan &amp; Mapstone, 2004; Wood, et al., 2012; Costa, et al., 2017). Taken together, the existing evidence makes it clear that efforts to enhance the conspicuity of both pedestrians and bicyclists – possibly including fluorescent apparel in daylight – are most effective when capitalizing on drivers’ perceptual sensitivity to biomotion. As such, this project explored the potential value of using fluorescent apparel strategically to make bicyclists more conspicuous to drivers during daylight hours. Specifically, we examined the influence of four different clothing configurations on the distances at which participants recognize the bicyclist wearing them. Methods. Visually healthy observers (N=186; mean age = 18.7 years) searched for bicyclists while a researcher drove them along a pre-determined route on public roads. Experimenters instructed participants to press a button on a numeric keypad each time they were confident that they recognized any person “on or with” a bicycle, who was “stopped or moving,” and who was “in or near the roadway.” Approximately seven minutes into their trip, participants encountered an experimenter wearing one of four outfits, pedaling (75 - 90 rpm) on a stationary bicycle on a sidewalk to the right of the roadway while facing away from the approaching vehicle. Experimenters delivered instructions to participants in such a way that was designed to limit participants’ expectancy that they would encounter a planted/scripted researcher on a bicycle during their trip. Participants’ button presses initiated a timer on the laptop computer operated by an experimenter in the back-seat of the research vehicle. The back-seat experimenter then stopped the timer once the test vehicle passed the test bicyclist. The elapsed time was used to calculate each participant’s response distance ( distance = speed × time). This technique has been used in numerous on-road pedestrian conspicuity experiments, and its accuracy has been verified for stationary roadway stimuli (e.g., Fekety, Edewaard, Stafford-Sewall, &amp; Tyrrell, 2016; Whetsel-Borzendowski, Stafford-Sewall, Rosopa, &amp; Tyrrell, 2015). After passing the experimenter bicyclist, the participants were informed that data collection had ended. Participants were then interviewed and debriefed while being driven back to the starting location. Each experimental session lasted approximately 30 minutes. Results. We performed a one-way between-subjects analysis of covariance (ANCOVA) to test the significance of the effects of clothing configuration on the response distances. The main effect of clothing was statistically significant, F(3,120) = 16.072, η2 = .287, p &lt; .001. Thus, the participants’ response distances significantly varied among the four clothing configurations. Post-hoc pairwise comparisons (Bonferroni) revealed that that a fluorescent yellow jersey did not significantly improve the cyclist’s conspicuity relative to a black jersey. However when the cyclist paired the fluorescent jersey with fluorescent yellow leggings, participants responded from a distance 3.3x farther than an identical outfit with black leggings. Discussion. The finding that fluorescent yellow leggings can provide a dramatic enhancement to bicyclist conspicuity is, we believe, a consequence of highlighting the bicyclist’s pedaling motion. The rhythmic up-down movements of a cyclist’s lower legs uniquely specify a pedaling motion that is visually distinct from, for example, a pedestrian walking or jogging. Further, considerable research has identified that highlighting a cyclist’s biological motion can provide powerful conspicuity enhancements. Thus fluorescent leggings can offer a powerful and low-tech tool for enhancing bicyclists’ daytime conspicuity.

Protecting aircrew from cold stress elevates heat stress

Aircrew need to wear an immersion suit to protect against hypothermia in the unlikely event of crashing into cold water. These clothing configurations provide insulation and water tight seals to reduce body heat loss in water; however, heat loss will also be impaired during normal flying activities in a warm cockpit. Therefore, this study evaluated the heat exchange properties of the Aircrew Protective Clothing Configuration (APCC) to determine the limitations it may impose to work in warm environments.

Effects of Different Levels of Refractive Blur on Nighttime Pedestrian Visibility.

The aim of this study was to systematically investigate the effect of different levels of refractive blur and driver age on nighttime pedestrian recognition and determine whether clothing that has been shown to improve pedestrian conspicuity is robust to the effects of blur. Nighttime pedestrian recognition was measured for 24 visually normal participants (12 younger mean = 24.9 ± 4.5 years and 12 older adults mean = 77.6 ± 5.7 years) for three levels of binocular blur (+0.50 diopter [D], +1.00 D, +2.00 D) compared with baseline (optimal refractive correction). Pedestrians walked in place on a closed road circuit and wore one of three clothing conditions: everyday clothing, a retro-reflective vest, and retro-reflective tape positioned on the extremities in a configuration that conveyed biological motion (known as "biomotion"); the order of conditions was randomized among participants. Pedestrian recognition distances were recorded for each blur and pedestrian clothing combination while participants drove an instrumented vehicle around a closed road course. The recognition distances for pedestrians were significantly reduced (P < 0.05) by all levels of blur compared with baseline. Pedestrians wearing biomotion clothing were recognized at significantly longer distances than for the other clothing configurations in all blur conditions. However, these effects were smaller for the older adults, who had much shorter recognition distances for all conditions tested. In summary, even small amounts of blur had a significant detrimental effect on nighttime pedestrian recognition. Biomotion retro-reflective clothing was effective, even under moderately degraded visibility conditions, for both young and older drivers.

Drivers' judgments of the effect of headlight glare on their ability to see pedestrians at night

IntroductionSeveral studies have concluded that pedestrians typically overestimate their own conspicuity to approaching drivers at night. The present experiments extended this research by exploring the accuracy of drivers' judgments of pedestrian conspicuity while facing varying degrees of headlight glare. MethodIn Experiment 1, participants on an open road estimated their ability to see a roadside pedestrian in each of two clothing configurations and with each of three different glare intensities present. In Experiment 2, participants responded to a roadside pedestrian under the same open road conditions; the participants were naïve with regard to both the position of the pedestrian and to the clothing and glare manipulations. ResultsConsistent with earlier research, estimates of response distance were, on the average, over three times greater than actual recognition distance. The extent to which participants overestimated conspicuity was greater when the pedestrian wore a retroreflective vest, and participants incorrectly judged that headlight glare would not degrade drivers' ability to see a pedestrian wearing a retroreflective vest. Conclusions and Practical ApplicationsThese results confirm that road users' understanding of issues involving drivers' night vision is limited. These misunderstandings may result in road users behaving in ways that increase the risk of nighttime collisions with pedestrians.

The Accuracy of Drivers’ Judgments of the Effects of Headlight Glare on Pedestrian Recognition at Night

In response to consumer complaints of being disabled by modern headlighting technologies, several recent studies have assessed whether drivers accurately assess the extent their ability to see is degraded by headlight glare. This research has suggested that drivers can overestimate the extent to which glare from headlights degrades their ability to see relatively simple stimuli. The present studies extended this research by quantifying the accuracy with which drivers judge that glare interferes with their ability to see pedestrians at night. In Experiment 1, 21 participants judged their ability to see a roadside pedestrian in two clothing configurations and with three intensities of glare present. In Experiment 2, 65 new participants responded to a roadside pedestrian in the same conditions. On average, participants overestimated the distance at which they would see a pedestrian by a factor of more than three. Interestingly, the participants’ overestimates were significantly greater when the pedestrian wore a retroreflective vest. The participants judged that headlight glare would have a larger effect on their ability to see a pedestrian who was not wearing retroreflective material than for a pedestrian who wore a retroreflective vest.

On-road measures of the visibility of pedestrians at night

Most collisions between vehicles and pedestrians occur at night. This experiment quantified the ability of drivers to detect pedestrians at night. Ten younger (M=27.8 yrs) and ten older (M=67.9 yrs) participants drove an instrumented car ten laps around an unilluminated 1.1 mile test track. Drivers pressed a dash-mounted touchpad when they recognized the presence of a pedestrian. A computer-based system measured recognition distances by interpreting the parallax provided by two synchronized digital video cameras mounted on the car's roof. Two pedestrians walked in place at different positions on the far shoulder. One pedestrian was in darkness and one was positioned just beyond a stationary pair of headlights that was a source of glare for the approaching driver. Across laps, drivers used both low and high beams and pedestrians wore four different clothing configurations. The effects of age, glare, clothing, and beam all significantly influenced both pedestrian identification (all p

Insertion loss of personal protective clothing

The use of personal protective clothing that covers the head is a common practice in many industries. Such personal protective clothing will impact the sound pressure level and the frequency content of sounds to which the wearer will be exposed. The use of such clothing, then, may impact speech and alarm audibility. A measure of the impact of such clothing is its insertion loss. Insertion loss measurements were performed on four types of personal protective clothing which utilize cloth and plastic hood configurations to protect the head. All clothing configurations tested at least partially cover the ears. The measurements revealed that insertion loss of the items tested was notable at frequencies above 1000 Hz only and was a function of material stiffness and acoustic flanking paths to the ear. Further, an estimate of the clothing's noise reduction rating reveals poor performance in that regard, even though the insertion loss of the test articles was significant at frequencies at and above 1000 Hz.

The Effectiveness of Educating Pedestrians about their own Nighttime Visibility

Pedestrians consistently overestimate their visibility at night. This experiment examined the effectiveness of several strategies of educating pedestrians about their own nighttime visibility. Forty-eight undergraduates were assigned to one of four groups: Lecture, Demo, Combo, or Control. Several weeks prior to data collection, participants in the Lecture and Combo groups had heard a lecture on applied visual physiology in their Introductory Psychology course. Immediately before data collection, participants in the Demo and Combo groups sat in a car and watched a nighttime pedestrian visibility demonstration. Under various clothing and illumination configurations, all participants walked towards a stationary car until they believed they were recognizable as a pedestrian. The lecture significantly reduced estimated visibility distances. This result is encouraging since it suggests public education efforts may be useful. The demonstration did not produce significant changes when participants wore either white or black clothing, but significantly increased estimates when wearing retroreflective strips.

Selected physiological and psychobiological responses to physical activity in different configurations of firefighting gear

The aim was to examine selected physiological and psychobiological responses to different configurations of protective firefighting gear. Career firefighters (n = 10) walked on a treadmill (3·5 km · h−1, 10% grade) for 15 min in three different clothing configurations. On separate days subjects wore: (a) ‘station blues’, (b) a hip boot configuration of firefighting gear, and (c) the current ‘NFPA 1500 standard’ gear. Physiological, psychophysical, and psychological measurements were recorded pre-exercise (5 min), during exercise (15 min), and during post-exercise recovery (10min). Repeated measures ANOVA revealed significant main effects for condition, time, and interaction (p < 0·001) for heart rate (HR), rectal temperature, mean skin temperature, oxygen consumption, breathing distress, thermal sensations, and affect. Furthermore, post hoc analyses revealed that all variables were significantly higher in the NFPA 1500 standard versus the hip boot or the station blues clothing configurations. These data s...