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Bus services are a fundamental component of transportation networks in Latin America, but buses often account for a disproportionately large number of environmental externalities. Electric buses (e-buses) are emerging as an effective and pragmatic option for reducing greenhouse gas emissions and local pollutants. However, e-buses are difficult to procure in Latin America because of existing procurement challenges in the region, especially as those challenges relate to forming contracts to deal with high upfront costs and unknown risks. To overcome these procurement issues, this paper presents a new contractual model, based on literature and case study research. This new model suggests the separation of bus service responsibilities into three separate actors: multiple bus procurement companies, one or multiple bus depots and charging infrastructure companies, and multiple bus operating companies. By separating bus service responsibilities, the proposed model would bring about three concrete improvements: lower costs to the transit system, better quality of service, and lower-emission fleet deployment.

Transit bus passenger loading changes significantly over the course of a workday. Therefore, time-varying vehicle mass as a result of passenger load becomes an important factor in instantaneous energy consumption. Battery-powered electric transit buses have restricted range and longer “fueling” time compared with conventional diesel-powered buses; thus, it is critical to know how much energy they require. Our previous work has shown that instantaneous transit bus mass can be obtained by measuring the pressure in the vehicle’s airbag suspension system. This paper leverages this novel technique to determine the impact of time-varying mass on energy consumption. Sixty-five days of velocity and mass data were collected from in-use transit buses operating on routes in the Twin Cities, MN metropolitan area. The simulation tool Future Automotive Systems Technology Simulator was modified to allow both velocity and mass as time-dependent inputs. This tool was then used to model an electrified and conventional bus on the same routes and determine the energy use of each bus. Results showed that the kinetic intensity varied from 0.27 to 4.69 mi−1 and passenger loading ranged from 2 to 21 passengers. Simulation results showed that energy consumption for both buses increased with increasing vehicle mass. The simulation also indicated that passenger loading has a greater impact on energy consumption for conventional buses than for electric buses owing to the electric bus’s ability to recapture energy. This work shows that measuring and analyzing real-time passenger loading is advantageous for determining the energy used by electric and conventional diesel buses.

AbstractEnvironmental histories that span the last full glacial cycle and are representative of regional change in Australia are scarce, hampering assessment of environmental change preceding and concurrent with human dispersal on the continent ca. 47,000 years ago. Here we present a continuous 150,000-year record offshore south-western Australia and identify the timing of two critical late Pleistocene events: wide-scale ecosystem change and regional megafaunal population collapse. We establish that substantial changes in vegetation and fire regime occurred ∼70,000 years ago under a climate much drier than today. We record high levels of the dung fungus Sporormiella, a proxy for herbivore biomass, from 150,000 to 45,000 years ago, then a marked decline indicating megafaunal population collapse, from 45,000 to 43,100 years ago, placing the extinctions within 4,000 years of human dispersal across Australia. These findings rule out climate change, and implicate humans, as the primary extinction cause.

Abstract Weather and climate variations on subseasonal to decadal time scales can have enormous social, economic, and environmental impacts, making skillful predictions on these time scales a valuable tool for decision-makers. As such, there is a growing interest in the scientific, operational, and applications communities in developing forecasts to improve our foreknowledge of extreme events. On subseasonal to seasonal (S2S) time scales, these include high-impact meteorological events such as tropical cyclones, extratropical storms, floods, droughts, and heat and cold waves. On seasonal to decadal (S2D) time scales, while the focus broadly remains similar (e.g., on precipitation, surface and upper-ocean temperatures, and their effects on the probabilities of high-impact meteorological events), understanding the roles of internal variability and externally forced variability such as anthropogenic warming in forecasts also becomes important. The S2S and S2D communities share common scientific and technical challenges. These include forecast initialization and ensemble generation; initialization shock and drift; understanding the onset of model systematic errors; bias correction, calibration, and forecast quality assessment; model resolution; atmosphere–ocean coupling; sources and expectations for predictability; and linking research, operational forecasting, and end-user needs. In September 2018 a coordinated pair of international conferences, framed by the above challenges, was organized jointly by the World Climate Research Programme (WCRP) and the World Weather Research Programme (WWRP). These conferences surveyed the state of S2S and S2D prediction, ongoing research, and future needs, providing an ideal basis for synthesizing current and emerging developments in these areas that promise to enhance future operational services. This article provides such a synthesis.

A new tangent energy-absorbing W-beam guardrail terminal that meets NCHRP Report 350 criteria has been developed. The terminal, designated the SKT-350, dissipates the energy of an encroaching vehicle by producing a series of plastic hinges in the W-beam as the terminal head is pushed down the guardrail. This energy-absorption concept allows for significantly lower dynamic forces on the encroaching vehicle, reducing the vehicle damage, the weight of the terminal head, the propensity for vehicle yaw and roll after impact, and the chances of buckling in the W-beam section. The energy required to move the head down the rail in this design is optimized for current criteria, but by modifying the bending geometry in the head, the average force to displace the head down the rail can be adjusted from values ranging from 11 to 60 kN (2,500 to 13,500 lb), meaning that the system can be easily modified to meet any future changes in safety performance standards. In addition to these important safety advantages, the terminal incorporates a unique cable anchor bracket that closely resembles a breakaway cable terminal anchor and a novel foundation tube design that facilitates the removal of broken posts during repair. Combining the features of reduced forces and head weight, a simple cable box, and more economical soil tubes allows the system to offer the advantages of both reduced cost and improved performance.

The city of Baltimore, Maryland, is now served by one heavy and one light rail line in addition to commuter rail service to Washington, D.C. However, the lines do not share any common stations and do not function as a network. The larger objective of this research was to evaluate ways in which the Baltimore transit system could be better integrated and contribute more to community well-being, environmental quality, and economic prosperity for all socioeconomic and racial and cultural groups. An underlying goal was to improve the mobility of a wider range of Baltimore residents so that their employment choices would not be limited by an underdeveloped transit system. This outcome was addressed in the context of the Intermodal Surface Transportation Efficiency Act of 1991, the Transportation Equity Act for the 21st Century, the Livable Communities Initiative, and the state of Maryland’s Smart Growth initiative. Only part of the larger agenda is presented here—the development of a community-based model for selecting and designing potential light rail line corridors in the larger system. The model used seven quality-of-life and livable community criteria—( a) potential to serve low-to moderate-income neighborhoods that have no direct access to public transportation (including bus access), ( b) high concentrations of employment opportunities along the route, ( c) highest number of intact commercial districts along the route, ( d) proximity to dense population centers (within a ¼-mi radius), ( e) proximity to numerous community social or cultural centers (including schools and churches), ( f) minimal physical environmental impacts, and ( g) the most potential to improve the pedestrian environment.

With rapid growth in the number of personal motor vehicles, Indian cities have been facing increasing congestion and worsening air quality. Yet until early 2005 little attention was paid to this problem, and remedial measures were focused largely on overpasses and new roadway capacity. Only Delhi, Calcutta, and Chennai had built functioning metro rail systems. However, by the second half of 2006, barely a year and a half later, the situation changed considerably, and public transport became the focus of attention in most large and medium-sized cities. This paper looks at the national initiatives that helped bring about those changes. The adoption of a national urban transport policy along with the launching of a national urban renewal mission with a sizable commitment of funds helped focus attention on improving public transportation. These were supplemented by a series of well-conceived and -planned initiatives, again led by the national government, to generate more widespread awareness of urban mobility problems and how they could be successfully addressed. The results were visible in a mere 18 months, by which time several cities had already formulated plans for significantly improved public transport and the first incremental phase of what will be India's first bus rapid transit system had become operational.