Locomotive Horn Detectability at Closely-Spaced Highway-Rail Grade Crossings

DTFR5317X00026Researchers assessed the feasibility of altering the locomotive horn sounding pattern of repetition at each crossing in a series of closely-spaced grade crossings by exploring the specific geometries and warning requirements for motorists in advance of such crossings. Acoustic modeling on five example scenarios showed that the locomotive horn would meet the auditory detection criteria out to a minimum of 1200 ft downstream of the primary crossing in those scenarios. The results from this analysis confirm that further exploration is needed on this topic, including assessing the feasibility and effectiveness for both detectability and driver response, to only sounding the locomotive horn prior to arriving at the first in a series of closely-spaced grade crossings

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb29