Investigation of flashing and intensity characteristics for vehicle-mounted warning beacons.

Reducing the potential for crashes involving front line service workers and passing vehicles is important for increasing worker safety in work zones and similar locations. Flashing yellow warning beacons are often used to protect, delineate, and provide visual information to drivers within and approaching work zones. A nighttime field study using simulated workers, with and without reflective vests, present outside trucks was conducted to evaluate the effects of different warning beacon intensities and flash frequencies. Interactions between intensity and flash frequency were also analyzed. This study determined that intensitiesof 25/2.5 cd and 150/15 cd (peak/trough intensity) provided the farthest detection distances of the simulated worker. Mean detection distances in response to a flash frequency of 1 Hz were not statistically different from those in response to 4 Hz flashing. Simulated workers wearing reflective vests were seen the farthest distances away from the trucks for all combinations of intensity and flash frequency.

Development of an Open-Source Tractor Driving Simulator for Tractor Stability Tests.

Developing devices for stability monitoring and rollover alerts is a promising possibility to prevent overturn events, which pose a severe risk to tractor operators. However, performing relevant tests with operators in the field is dangerous and impractical. As an alternative, this work identifies the challenges of simulating a tractor driving environment in a laboratory and details the solutions put in place to develop a tractor driving simulator at Penn State University. The simulator includes an instrumented tractor cab mounted on a custom motion base, a 2.43 m tall, 360° high-definition screen, a sound system, and a nine-computer network running open-source software that can be used to conduct experiments and simulate driving scenarios relevant to tractor instabilities. The system is used for an experiment that evaluates the driver's ability to perceive tilt angles at various tilt and roll combinations. Pilot-test results show that roll and pitch are systematically overestimated, producing perceptual errors that are unbiased, independent for roll and pitch, and typically have magnitudes of 4°. These results can aid the development of instability monitoring systems by considering human tilt perception to set alert thresholds. Future projects and applications of the tractor driving simulator are also discussed.