This paper focuses on the safety issue for cyclists and pedestrians at unsignalized intersections. The cycling speed needs to be calmed when approaching the intersection. This study proposes and deploys an integrated portable ultra-wideband/inertial navigation system (UWB/INS) to extract cycling trajectories for a cycling safety study. The system is based on open-source hardware and delivers an open-source code for an adaptive Kalman filter to enhance positioning precision for data quality assurance at an outdoor experimental site. The results demonstrate that the system can deliver reliable trajectories for low-mobility objects. To mitigate accident risk and severity, varied cycling speed calming measures are tested at an experimental site. Based on the trajectory data, the statistical features of cycling velocities are evaluated and compared. A new proposed geometric design is found to be most effective when compared with conventional traffic signs.

To estimate traffic facility-oriented particulate matter (PM) emissions, emission factors are both necessary and critical for traffic planners and the community of traffic professionals. This study used locally calibrated laser-scattering sensors to collect PM emission concentrations in a tunnel. Emission factors of both light-duty and heavy-duty vehicles were found to be higher in autumn compared to summer. Based on this study’s data analysis, PM emissions, in terms of mass, have a strong seasonal effect. The study also conducted a PM composition test on normal days and during haze events. Preliminary results suggested that the transformation of gaseous tailpipe emissions to PM is significant within the tunnel during a haze event. This study, therefore, recommends locally calibrated portable devices to monitor mobile-source traffic emissions. The study suggests that emission factor estimation of traffic modeling packages should consider the dynamic PM formation mechanism. The study also presents traffic policy implications regarding PM emission control.

In order to investigate the impact of various highway traffic prohibition and warning signs on four-lane highways in flat regions, electroencephalography (EEG) data from drivers were collected through field experiments. A comprehensive analysis was conducted on EEG potential, time-frequency characteristics, topography, power, and derived indicators. The study aimed to objectively evaluate the effects of different traffic signs on driver behavior by examining the EEG characteristics exhibited by drivers when observing various types of traffic prohibition and warning signs. The result shows that (1) The alterations in frontal lobe potential and EEG power are significantly more pronounced than those observed in a resting state when drivers encounter traffic prohibition and warning signs, suggesting a heightened activation level in the relevant brain regions. This implies that the presence of traffic prohibition and warning signs in this context effectively alerts drivers. (2) Notable differences were identified in the EEG relative power of the β wave and the θ/β power indicator across six categories of traffic prohibition and warning signs, which include crossroads, weight limit, roundabout, T-junction, speed limit, and removal speed limit signs. Specifically, the relative power of the β wave was found to be higher, while the θ/β power indicator was lower for speed limit and removal speed limit signs, indicating that these types of traffic signs are more effective in capturing drivers' attention. (3) Conversely, the relative power of the β wave was lower and the θ/β power indicator was higher for weight limit, crossroads, and T-junction signs, suggesting that these signs are less effective in attracting sufficient attention from drivers. This diminished effectiveness may be attributed to factors such as drivers' habitual behaviors and the surrounding road environment. Consequently, it is recommended that greater emphasis be placed on optimizing weight limit, crossroads, and T-junction signs when enhancing the traffic prohibition and warning signs along this segment of the highway. The results of this study may serve as a valuable reference for the optimization of traffic prohibition and warning signs on similar highways.