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The social functions of urbanized areas are highly dependent on and supported by the convenient access to public transportation systems, particularly for the less privileged populations who have restrained auto ownership. To accurately evaluate the public transit accessibility, it is critical to capture the spatiotemporal variation of transit services. This can be achieved by measuring the shortest paths or minimum travel time between origin-destination (OD) pairs at each time-of-day (e.g. every minute). In recent years, General Transit Feed Specification (GTFS) data has been gaining popularity for between-station travel time estimation due to its interoperability in spatiotemporal analytics. Many software packages, such as ArcGIS, have developed toolbox to enable the travel time estimation with GTFS. They perform reasonably well in calculating travel time between OD pairs for a specific time-of-day (e.g. 8:00 AM), yet can become computational inefficient and unpractical with the increase of data dimensions (e.g. all times-of-day and large network). In this paper, we introduce a new algorithm that is computationally elegant and mathematically efficient to address this issue. An open-source toolbox written in C++ is developed to implement the algorithm. We implemented the algorithm on City of St. George’s transit network to showcase the accessibility analysis enabled by the toolbox. The experimental evidence shows significant reduction on computational time. The proposed algorithm and toolbox presented is easily transferable to other transit networks to allow transit agencies and researchers perform high resolution transit performance analysis. [ABSTRACT FROM AUTHOR]

Tornadoes produced by right-moving supercells (RMs) and quasi-linear convective systems (QLCSs) are compared across the contiguous United States for the period 2003–21, based on the maximum F/EF-scale rating per hour on a 40-km horizontal grid. The frequency of QLCS tornadoes has increased dramatically since 2003, while the frequency of RM tornadoes has decreased during that same period. The finding of prior work that the most common damage rating for QLCS tornadoes at night is EF1 persists in this larger, independent sample. A comparison of WSR-88D radar attributes between RM and QLCS tornadoes shows no appreciable differences between EF0 tornadoes produced by either convective mode. Differences become apparent for EF1–2 tornadoes, where rotational velocity is larger and velocity couplet diameter is smaller for RM tornadoes compared to QLCS tornadoes. The frequency of tornadic debris signatures (TDSs) in dual-polarization data is also larger for EF1–2 RM tornadoes when controlling for tornadoes sampled relatively close to the radar sites and in those occurring during daylight versus overnight. The weaker rotational velocities, broader velocity couplet diameters, and lower frequencies of TDSs both close to the radar and at night for QLCS EF1 tornadoes suggest that a combination of inadequate radar sampling and occasional misclassification of wind damage may be responsible for the irregularities in the historical record of QLCS tornado reports. Significance Statement: A comparison of radar attributes between tornadoes with right-moving supercells and squall-line mesovortices suggests some irregularities in squall-line tornado records in the contiguous United States. The irregularities appear to be the result of both inadequate radar sampling for the relatively shallow squall-line tornadoes and occasional misclassification of wind damage with the lack of other corroborating evidence, especially overnight. [ABSTRACT FROM AUTHOR]

A variety of variables influence the optimal tilt angle of a PV panel, including the characteristics of the panel, the local seasonal weather variations, the number of daylight hours the panel is exposed to and the ambient temperature of the surroundings. In this study, the optimal PV tilt angle and maximum energy output of PV arrays was calculated for every county in the United States and compared against the practice of setting the PV tilt angle to be equivalent to the latitude angle of the PV geographic location. A PVWatts API, implemented through Python, was used in conjunction with the SciPy optimization package to find the optimal tilt angle for each county using a direct line search algorithm. Most counties (95.8%) showed a difference between the location latitude and the optimal tilt of more than one degree. Many counties showed a deviation of 2–6° lower than the location latitude. The variation of daylight hours had the largest influence on tilt angle and seasonal cloud cover and ambient temperature had varying levels of influence. Generally, winter cloud cover decreased the optimal tilt angle whereas high summer temperatures increased the tilt angle. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes a method for testing current and emerging daylight availability metrics such as daylighting factor, daylight autonomy, useful daylight illuminance and LEED 3.0 requirements against building occupant assessments of a daylit space. During spring 2011 the method was tested as a classroom exercise by 60 architectural students enrolled in two graduate-level building science courses in the 2nd floor studio space of le Corbusier’s Carpenter Center in Cambridge, MA, USA. The results from this test yielded that the Lighting Measurement protocol for Spatial Daylight Autonomy, that is current being developed by the Illuminating Engineering Society of North America (IESNA) daylighting metrics committee, reproduced the student assessments of the daylit area in the space more reliably than the other tested daylight availability metrics. These findings are preliminary and still need to be validated and refined in other spaces. Apart from providing valuable data points for scientific experiments, the method also has substantial educational value as a teaching exercise for architectural students to develop an intuitive understanding of contemporary daylight performance metrics, as well as a feeling of how their personal lighting preferences compare to these metrics. [Copyright &y& Elsevier]

This study explores the joint effect of visibility and warning devices on driver injury severity at the highway-rail grade crossings (HRGCs), while also considering other contributing factors. For this purpose, four mixed logit models are developed to estimate the determinants of driver injury severity considering the combinations of visibility conditions (daylight vs. no daylight) and type of warning devices (active vs. passive warning). The models were calibrated using the data obtained from the USDOT Federal Railroad Administration for HRGC crashes that occurred over a ten-year period 2008-2017 across the United States. A temporal transferability test was conducted and confirmed the stability of model specifications considering a ten-year span of collected data. The pseudo-elasticity analysis was conducted to ascertain marginal impact of the contributing factors on driver injury severity in each model. While the vehicle speed, train speed, time of day and driver age are found to be common significant factors among the four models, there are marked differences between parameters associated with various crash factors. The study provides new insight into the driver injury severity in train-vehicle collisions considering visibility and type of warning devices, which can help in setting up proper policies to improve safety at HRGCs. [ABSTRACT FROM AUTHOR]

The Illuminating Engineering Society of North America (IESNA) Lighting Handbook recommends illuminance criteria for specific applications to raise the ''minimum standard of care'' required of lighting design to meet human, economic environmental, and architectural concerns. Specific criteria for daylighting of auditoriums (i.e., large rooms) focus on the importance of daylighting integration, control and flexibility, illuminance levels, light distribution, color appearance, and glare. A new skylight design for day and night illumination of a large volume room is proposed. The feasibility of this unique design uses clerestory windows, also known as a roof monitor, and an outdoor lighting array. The design illuminates a room 100-feet wide, 100-feet long, and 75-feet high, located at 408-north latitude. Comparisons have been made to flat skylight wells for the same volume. The demonstrated design meets lighting criteria that satisfy IESNA standards for day and night to play basketball, a task that requires low contrast and involves small sized objects, like a basketball. The design has been tested with AGI32 software created by Lighting Analysts, Inc of Littleton, Colorado. Results show the new skylight meets IESNA criteria F (for tasks like basketball) during the daytime with an assist by external lighting as the setting sun reduces the daylight. [ABSTRACT FROM AUTHOR]