M. Jennifer Klena’s research while affiliated with Pennsylvania State University and other places

Research and common sense attest to the fact that on-premise projecting signs are more detectable and are readable further away and at smaller sizes than wall-mounted signs. The objective of the current study was to conduct a small-scale field validation of earlier research on minimum letter heights for wall signs and to provide associated minimum square footage for these signs. Eight wall signs that varied in letter height and lateral offset were identified for evaluation on two roadways that varied in posted speed limit and cross-section in Nags Head, North Carolina. Using an empirical procedure involving driving and walking toward the signs, the legibility distances for these signs were evaluated and were found to compare favorably to past research that employed an analytical approach. An equation to determine sign size in square feet was also developed. Future research to further these findings is outlined.

Freestanding on-premise signs are commercial signs that are not attached to buildings or other structures and include ground-mounted, monument, pylon, and pole signs. This report focuses on issues related to the appropriate mounting height of freestanding signs. The objective of this report is to develop best practices for optimal freestanding on-premise sign mounting height based on roadway factors, sign visibility, and traffic safety, relying on existing research and practice and basic geometry, and describing variations for different road types and sign lateral offsets. To achieve this, the existing on-premise and traffic sign mounting height research was reviewed, and the current state-of-the-practice was summarized. In addition, a technical analysis of on-premise sign height and sign visibility based on roadway cross-section and driver-to-sign sightlines was conducted.

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.

The main objective of this research was to compare the legibility distance of the negative-contrast Clearview typeface with that of comparable FHWA Standard Alphabets on black-on-white signs in the daytime and nighttime for older and younger motorists. Mixed-case Clearview (2-B, 3-B, and 4-B) was compared with both mixed-case and uppercase FHWA Standard Alphabets (Series C, D, and E). In addition, the researchers evaluated the effects of letter height on the legibility distance of mixed-case Clearview. A small set of positive-contrast white-ongreen signs were displayed to compare Clearview Typefaces 2-W, 3-W, and 4-W with FHWA Standard Alphabet Series C, D, and E, which are all mixed case. Overall, signs that used Clearview negative-contrast in mixed case performed as well as FHWA Standard Alphabets in uppercase (even though the Clearview fonts took up less sign space than the FHWA Standard Alphabets) and better than mixed-case FHWA Standard Alphabets in both daytime and nighttime. Overall, Clearview in positive contrast (white on green) outperformed the comparable FHWA Standard Alphabets. In addition, a survey conducted with state departments of transportation of their current use of Clearview in positive contrast and their potential use of Clearview in negative contrast is discussed.