Driver responses to green and red vehicular signal countdown displays: Safety and efficiency aspects

This study investigates the effects of green signal countdown display (GSCD) and red signal countdown display (RSCD) on driver behaviours, and thus on intersection safety and efficiency. Three driver responses to GSCD, including late-stopping ratio, dilemma zone and decision to cross, and three driver responses to RSCD, including early start ratio, start-up delay, and discharge headway are observed and analyzed. Results show that although GSCD can reduce late-stopping ratio, the dilemma zone is increased by about 28 m and the decision to cross will be more inconsistent among the approaching vehicles, creating a potential risk of rear-end crashes. Additionally, following the provision of a green countdown the number of vehicles ejecting to cross the intersection reduces. On the other hand, comparisons among four observation periods examining the effects of RSCD-before-RSCD, 1.5 months after-RSCD, 3.0 months after-RSCD and 4.5 months after-RSCD, show that although RSCD significantly reduces the early start ratios of the leading vehicles in various waiting areas, the ratios soon return to their before-RSCD levels, suggesting that RSCD does not significantly improve intersection safety over the longer term. However, RSCD effectively reduces start-up delay, saturated headway, and cumulative start-up delay at 4.5 months after-RSCD installation. Thus, RSCD enhances intersection efficiency. RSCD is clearly less controversial and more beneficial than GSCD.

A cross-cultural comparison of perceived hazard in response to warning components and configurations: US vs. China

There is increasing momentum towards international harmonization of warning standards. Therefore, it is critical to determine the applicability of existing standards across different cultures. Perceived hazard in response to isolated warning components (colors, signal words and symbols) and warning configurations was examined as a function of culture of the product-user (US vs. China) to determine the extent to which ANSI (American National Standards Institute)-recommended components/configurations communicate the expected level of hazard across cultures. 40 college students in the US and 43 in China rated colors, signal words, symbols, and complex configurations on a scale from 1 (not at all hazardous) to 9 (extremely hazardous). US participants consistently provided higher ratings of perceived hazard than Chinese participants. Cross-cultural differences were also observed in the relative levels of perceived hazard assigned to different levels of a label component, particularly in response to colors. However, relative levels of perceived hazard among more complex configurations were similar across culture, even though Chinese participants continued to provide lower absolute ratings of perceived hazard. These results have important implications--if it is assumed that perceived hazard-level must attain some threshold value in order to trigger compliance, then differences in perception could result in a failure of product-users to take appropriate precautions.

Drivers' and cyclists' experiences of sharing the road: incidents, attitudes and perceptions of visibility

This study explored the beliefs and attitudes of cyclists and drivers regarding cyclist visibility, use of visibility aids and crashes involving cyclists and motorists. Data are presented for 1460 participants (622 drivers and 838 cyclists) and demonstrate that there are high rates of cyclist-vehicle crashes, many of which were reported to be due to the driver not seeing the cyclist in time to avoid a collision. A divergence in attitudes was also apparent in terms of attribution of responsibility in cyclist-vehicle conflicts on the road. While the use of visibility aids was advocated by cyclists, this was not reflected in self-reported wearing patterns, and cyclists reported that the distance at which they would be first recognised by a driver was twice that estimated by the drivers. Collectively, these results suggest that interventions should target cyclists' use of visibility aids, which is less than optimal in this population, as well as re-educating both groups regarding visibility issues.

Drivers' perceptions and reactions to roadside memorials

Despite their growing popularity in North America, little research has been conducted on understanding the effects of roadside memorials on drivers' behaviour. In this study, an online survey of 810 drivers found that public opinions on the policy options as well as drivers' self-reported reactions to the presence of roadside memorials were fairly divided. In addition, an on-road experiment was conducted to examine the short term effects of roadside memorials at two intersections. Our results showed that the number of red light violations was reduced by 16.7% in the 6 weeks after the installation of the mock memorials compared to the 6 weeks before whereas the number of violations at two comparison sites experienced an increase of 16.8%.

Designed for a better life. Interview by Daniel Allen

A new design audit tool contains a series of resources for carrying out an assessment of environments used by people with dementia. It is suitable for refurbishment projects or new buildings and can be used across a range of settings, including day centres, hospital wards, care homes and GP surgeries.

Properties of light reflected from road signs in active imaging

Night vision systems in vehicles are a new emerging technology. A crucial problem in active (laser-based) systems is distortion of images by saturation and blooming due to strong retroreflections from road signs. We quantify this phenomenon. We measure the Mueller matrices and the polarization state of the reflected light from three different types of road sign commonly used. Measurements of the reflected intensity are also taken with respect to the angle of reflection. We find that different types of sign have different reflection properties. It is concluded that the optimal solution for attenuating the retroreflected intensity is using a linear polarized light source and a linear polarizer with perpendicular orientation (with regard to the source) at the detector. Unfortunately, while this solution performs well for two types of road sign, it is less efficient for the third sign type.

The effects of driver factors and sign design features on the comprehensibility of traffic signs

PROBLEM

This paper addresses the effects of driver factors and sign design features on the comprehensibility of traffic signs.

METHODS

A survey was designed to capture subjects' personal particulars, ratings on sign features, and comprehension scores, and then administered to 109 Hong Kong full driving license holders.

RESULTS

Years with driving license and education level were significant predictors of sign comprehensibility. Contrary to expectation, the driver factors of age group, years of active driving, hours of driving, last time driving, driving frequency, and non-local driving experience had no effect on comprehension performance. Sign familiarity was correlated with comprehension score for licensed drivers, whereas sign concreteness, simplicity, and meaningfulness were not.

IMPACT ON INDUSTRY

The results of this study provide useful guidelines for designing more user-friendly traffic signs in the future. It identified particular driver groups who lacked good understanding of traffic signs, and this information may assist the relevant organizations to better allocate traffic training resources, and better target future studies of traffic sign comprehension.

Warning symbols as reminders of hazards: impact of training

Prior research indicates that many warning symbols are poorly understood. However Lesch [Lesch, M.F., 2003. Comprehension and memory for warning symbols: Age-related differences and impact of training. J. Safety Res. 34, 495-505] found that accident scenarios could be used to improve comprehension of warning symbols. The current study further investigated the potential benefits of accident scenario training. During training, warning symbols with verbal labels corresponding to the meaning of the symbol were paired with accident scenarios which expanded on the nature of the hazard, the required/prohibited actions, as well as the possible consequences of failing to comply. A number of measures were obtained prior to, and following (immediately and 2 weeks later), the accident scenario training: comprehension across three knowledge types (verbal label, required/prohibited actions, potential consequences of failure to comply), ratings of agreement with statements reflecting perceived control, and ratings of hazard and intent to comply. Benefits of training were observed on all dependent measures: Comprehension improved from 43 to 82% correct, reaction times were reduced by about 2s, and level of confidence in correct responses increased by 23%. Ratings of perceived hazard, intent to comply, and perceived control over accident/injury involvement also increased. It is suggested that accident scenario training can be used to help prevent accidents and injuries by ensuring that responses to warnings are "sure and swift".

Rectification of legibility distance in a driving simulator

Visual differences lead to differences in the legibility distances of traffic signs between driving simulators and real road environments. To ensure that the legibility distance in a simulator is similar to that in the real world, this study proposes a theoretical equation for predicting legibility distance and a simple algorithm for determining the magnifying power of a traffic sign for a display system in a simulator. Experiments of traffic sign recognition using a simulator were conducted under quasi-static and dynamic driving conditions. On-road tests were also carried out under quasi-static and dynamic driving conditions. Thirty healthy and non-disabled volunteers were recruited. The experimental results showed that the proposed theoretical equation for predicting legibility distance and the simple algorithm for determining the magnifying power of traffic signs reduced the difference in legibility distances between the simulator and real road environment under quasi-static and dynamic driving conditions.

A comparison of two training methods for improving warning symbol comprehension

This study compared the effectiveness of two different types of training in improving comprehension of warning symbols by younger (aged 20-35 years) and older adults (aged 50-70 years). The verbal label training paired the symbol with a label describing its meaning while the accident scenario training further expanded on the nature of the hazard, the required/prohibited actions, as well as the possible consequences of failing to comply. Contrary to prior research (e.g., [Lesch, M.F., 2003. Comprehension and memory for warning symbols: age-related differences and impact of training. J. Safety Res. 34, 495-505]), there was no difference in comprehension for younger and older adults prior to training, with both groups only obtaining about 40% correct responses. Both types of training improved performance on a subsequent comprehension test. However, the accident scenario training produced a higher percentage of correct responses, greater confidence in those responses, as well as a longer-lasting reduction of reaction times. In order to further improve symbol design, as well as training to address comprehension difficulties, future research should more closely examine symbol characteristics that influence comprehension.

Driving, navigation, and vehicular technology: experiences of older drivers and their co-pilots

OBJECTIVE

The objective of this article is to explore relationship between older drivers and their passengers (co-pilots) and potential implications of in-vehicle navigation technology on their driving safety.

METHODS

Semi-structured interviews were conducted with 44 healthy, community-dwelling older adults (aged 60-83) or 22 married couples. Males identified themselves as drivers and females identified themselves as passengers (i.e., co-pilot).

RESULTS

Findings indicate that operating a motor vehicle in older adulthood is a shared activity between drivers and passengers. Older drivers and co-pilots reported their level of interaction depended on their familiarity with their route. Navigating unfamiliar areas, particularly large urban centers, was identified as the most challenging driving situation. Participants identified their level of collaboration would increase with the advent of in-vehicle navigation technology. Safety concerns related to the use of this technology, included distraction of both drivers and passengers. Differences amongst couples in their perceptions of using this technology were linked to their level of experience with using other forms of technology.

CONCLUSIONS

Older drivers and passengers identified working closely together when operating a motor vehicle. Further investigation into the effects of in-vehicle navigation technology on the driving safety of older drivers and their co-pilots is warranted.

The guessability of traffic signs: effects of prospective-user factors and sign design features

This experiment investigated the relationships between the characteristics of prospective-users of traffic signs (people who will use the signs in the future) and the guessability of traffic signs, and also examined the effects of sign design features on the guessability of traffic signs. Forty-one Hong Kong Chinese subjects guessed the meanings and rated the sign features of 120 Mainland Chinese signs. Contrary to expectation, cycling experience and previous experience with sign information had no effect on sign guessing. Males and females with similar education level had similar guessing performance. Previous experience of visiting Mainland China was a significant predictor of guessing performance. Family ownership of a vehicle was associated with guessing performance for subjects who intended to become a driver and for those with car game experience. Subjects who claimed to pay attention to traffic signs in daily life performed better at sign guessing than those who did not. Traffic incident experience did not seem to enhance awareness of, or knowledge about, traffic signs. Guessability of a sign varied with the five design features of; familiarity, concreteness, simplicity, meaningfulness, and semantic closeness of the sign. Semantic closeness was the best predictor of guessability score, followed by familiarity, meaningfulness, concreteness, and simplicity. In order to design more user-friendly traffic signs and effective ways of using them, it is suggested that designers develop and evaluate signs according to the relative importance of the five sign features.

The Effects of Signage and the Physical Environment on Stair Usage

Background:

Physical activity (PA) is a health behavior that most Americans do not participate in at recommended levels.

Methods:

We sought to increase PA by use of motivational signs in selected buildings. Because physical environments are known to influence PA, the relationship of building characteristics and stair usage was also assessed. One pre- and two post-intervention observations were conducted.

Results:

The proportion of those using the stairs increased from baseline to the second data collection, (χ2 = 39.31, p < 0.01) and baseline to a final data collection (χ2 = 10.1, p < 0.01). Built environment factors, including steps to the next higher floor and the number of floors in the building were consistent predictors of stair use. With signs positioned, the visibility of the stairs while standing in front of elevators became a significant predictor of stair usage.

Conclusions:

Motivational signs and characteristics of built environments are associated with increased stair usage.