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Objectives: In this article, we seek to determine how sensitive road cyclists are to vertical vibration transmitted while riding a road bicycle and to propose metrics for the evaluation of dynamic comfort.Background: Road cyclists are exposed to random-type excitation due to road roughness. Vibration transmitted affects dynamic comfort. But how sensitive are cyclists to vibration level? What are the best metrics to measure the amount of vibration transmitted to cyclists? Previous studies used sinusoidal excitation with participants on rigid seats and measured acceleration.Methods: We use a psychophysical estimation of Just Noticeable Differences in Level (JNDL) for vertical vibration transmitted to cyclists on a road simulator. In Experiment 1, we estimate the JNDL for whole-body vibration using vertical excitation on both wheels simultaneously (20 male cyclists). In Experiment 2, we estimate the JNDL at two different points of contact by applying the same signal to only the hands or the buttocks (9 male cyclists).Results: The JNDLs are expressed in terms of acceleration and power transmitted to the cyclist. We compare the JNDLs expressed with these 2 metrics and measured at different points of contact.Conclusion: Using these two metrics and at all points of contact, vibration magnitude needs to be reduced by at least 15%, for the change to be detectable by road cyclists.Application: A road bicycle needs to transmit at least 15% less vibration for male cyclists to detect an improvement in dynamic comfort. Dynamic bicycle comfort can be measured in terms of a new metric: power transmitted to the cyclist. [ABSTRACT FROM AUTHOR]

Objective: We examined how sending mobile-device warnings to texting pedestrians when they initiate an unsafe road crossing influences their decisions and actions.Background: Pedestrian texting has been identified as a key risk factor in pedestrian-vehicle collisions. Advances in sensing and communications technology offer the possibility of providing pedestrians with information about traffic conditions to assist them in safely crossing traffic-filled roadways. However, it is unclear how this information can be most effectively communicated to pedestrians.Method: We examined how texting and nontexting pedestrians crossed roads with continuous traffic in a large-screen, immersive pedestrian simulator using a between-subjects design with three conditions: texting, warning, and control. Texting participants in the warning condition received an alarm on their cell phone when they began to cross a dangerously small gap.Results: The results demonstrate the detrimental influence of texting on pedestrians' gap selection, movement timing, and gaze behavior, and show the potential of warnings to improve decision making and safety. However, the results also reveal the limits of warning texting participants once they initiate a crossing and possible overreliance on technology that may lead to reduced situation awareness.Conclusion: Mobile devices and short-range communication technologies offer enormous potential to assist pedestrians, but further study is needed to better understand how to provide useful information in a timely manner.Application: The technology for communicating traffic information to pedestrians via mobile devices is on the horizon. Research on how such information influences all aspects of pedestrian behavior is critical to developing effective solutions. [ABSTRACT FROM AUTHOR]

Objective: This paper's first objective is to determine whether motor priming assistance (consisting of directional steering wheel vibrations) can be of some benefit compared with more traditional auditory (lateralized sound) or vibratory (symmetric steering wheel oscillation) warning devices. We hypothesize that warning devices favor driving situation diagnosis, whereas motor priming can improve the initiation of action even further. Another objective is to assess the possible benefits of using multimodal information by combining auditory warning with simple steering wheel vibration or motor priming.Background: Within the context of active safety devices, the experiment dealt with moderately intrusive driving assistance devices that intervene when a certain level of risk in terms of lane departure is reached.Method: An analysis of the steering behavior of 20 participants following episodes of visual occlusion was carried out. Five warning and motor priming devices were compared.Results: All tested devices improved the drivers' steering performance, although their effects were modulated by the drivers' risk assessment. However, performance improvements were found to be greater with a motor priming device. No additional performance enhancement was observed when auditory warning was added to steering wheel vibration or motor priming devices.Conclusion: This study confirms the hypothesis that the direct intervention of motor priming at the action level is more effective than a simple warning, which intervenes upstream in situation diagnosis. Multimodal information did not seem to improve driver performance.Application: This study proposes a new kind of lateral control assistance, which acts at a sensorimotor level, in contrast with traditional warning devices. [ABSTRACT FROM AUTHOR]

The goal of this study was to determine if traffic signals that are synchronized along a route are associated with fewer red-light violations than traffic signals that are not synchronized. A total 3600 cycles of traffic signals at 12 intersections along 2 major urban arteries were observed. Synchronized intersections were effective in reducing the likelihood of red-light running (RLR) by (a) providing fewer opportunities than nonsynchronized intersections for RLR and (b) having a lower rate of RLR relative to the number of opportunities. After adjustment for the number of opportunities, the odds of entering the intersections in red in synchronized intersections were nearly 1/7 the odds of RLR in nonsynchronized intersections. Congestion reduced the effectiveness of synchronized intersections relative to nonsynchronized intersections. Male drivers were slightly more likely to run red lights than female drivers, and the effects of synchronization were fairly constant across age, gender, and the presence or absence of passengers. Actual or potential applications of this research involve signal synchronization to reduce aggressive driving in general and RLR in particular. [ABSTRACT FROM AUTHOR]