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Public transit systems with efficient designs and operating plans can reduce greenhouse gas (GHG) emissions relative to low-occupancy transportation modes, but many current transit systems have not been designed to reduce environmental impacts. This motivates the study of the benefits of design and operational approaches for reducing the environmental impacts of transit systems. For example, transit agencies may replace level-of-service (LOS) by vehicle miles traveled (VMT) as a criterion in evaluating design and operational changes. Previous studies have demonstrated in an idealized singletechnology transit system the potential of reducing GHG emissions by lowering the transit level-of-service (LOS) provided to the users. In this research, we extend the analysis to account for a more realistic case: a transit system with a hierarchical structure (trunk and feeder lines) providing service to a city where demand is elastic. By considering the interactions between the trunk and the feeder systems, the study provides a quantitative basis for designing and operating integrated urban transit systems that can reduce GHG emissions and costs to both transit users and agencies. The study shows that highly elastic transit demand may cancel emission reduction potentials resulting from lowering LOS, due to demand shifts to lower occupancy vehicles, causing unintended consequences. However, for mass transit modes, these potentials are still significant. Transit networks with buses, bus rapid transit or light rail as trunk modes should be designed and operated near the cost-optimal point when the demand is highly elastic, while this is not required for metro. We also find that the potential for unintended consequences increases with the size of the city. The results are robust to uncertainties in the costs and emissions parameters. The study also includes a discussion of a current transit system. Since many current transit systems have not yet been optimally designed, it should be possible to reduce their GHG emissions without sacrificing the LOS. A case study of the MUNI bus system in San Francisco is used to validate this conjecture. The analysis shows that reductions in GHG emissions can be achieved when societal costs are reduced simultaneously. The cost-optimal MUNI bus system has a societal cost of 0.15 billion $/year and emits 1680 metric tons of greenhouse gases. These figures only amount to about half of the cost and a third of the emissions in the current MUNI bus system. The optimal system has a lower spatial availability but a higher temporal availability of bus service than the current system, which highlights the potential benefits of providing more frequent express bus services.

Environmental assessments have been developed with increasing emphasis since the wide-scale emergence of environmental concerns in the 1970s. However, after decades there is still plenty of room left for development. These assessments are also rapidly becoming more and more crucial as we seem to be reaching the boundaries of the carrying capacity of our planet. Assessments of the emissions from the built environment and especially of the interactions between human communities and emissions are in a very central role in the quest to solve the great problem of sustainable living. Policy- makers and professionals in various fields urgently need reliable data on the current conditions and realistic future projections, as well as robust and scientifically defensible models for decision making. This recognition was the main motivation to call for this Focus Issue, and the published contributions truly highlight the same point. This editorial provides brief summaries and discussions on the 16 articles of the Focus Issue, depicting the several interesting perspectives they offer to advance the state of the art. Now we encourage academics, practitioners, government, industry, individual consumers, and other decision makers to utilize the available findings and develop the domain of environmental assessment of the built environment further. Indeed, we hope that this Focus Issue is merely a kernel of a significantly large future body of literature.

Erythropoietin (EPO) is a cytokine hormone that regulates blood cell production. EPO is used for clinical treatment of anemia and renal disease, but may be best known as a performance enhancing drug due to its activity as an erythropoiesis stimulating agent. EPO is a small protein that is heavily glycosylated (40% by mass), and displays large N-linked glycans characterized by high sialic acid content and poly-lactosamine repeats. Thus, it is an ideal model for understanding the effect of glycan modifications on protein dynamics and conformation. We have performed H/DX MS experiments on two recombinant EPOs from CHO cells using a custom microfluidic chip MS system. The analytical platform permits low flow (300 nanoliter per minute) H/DX MS on sample quantities in the 200 femtomole per timepoint range, a sensitivity which is ∼100X higher than that provided by a typical H/DX MS system. Analysis of the EPO samples revealed EX1 type kinetics in two of the four alpha helices of the molecule. These data are consistent with the fact that these two alpha helixes are not involved in either of the two disulfide bridges which stabilize EPO and are required for biological activity. The data thus indicate that these relatively untethered secondary structures take part in rare but extensive unfolding events under native conditions. Comparison of the two recombinant EPO samples revealed similar deuterium uptake profiles at the timepoints tested, likely a reflection of their mutual origin from CHO cells. We obtained high sequence coverage from our H/DX MS experiments despite the high glycan content of the molecule. We conclude that H/DX MS is an ideal platform for comparing extensively post-translationally modified recombinant proteins and that H/DX MS experiments can be optimized for situations where sample quantity is limited.

The passenger transportation modes of auto, bus, heavy rail, light rail and air are critical systems relied upon for business and leisure. When considering their environmental effects, most studies and policy focus on the fuel use of the vehicles, and ignore the energy and other resource inputs and environmental outputs from the life cycles of necessary infrastructures, fuels, and vehicles. The goal of this project is to develop comprehensive life-cycle assessment (LCA) models to quantify the energy inputs and emissions from autos, buses, heavy rail, light rail and air transportation in the U.S. associated with the entire life cycle (design, raw materials extraction, manufacturing, construction, operation, maintenance, end-of-life) of the vehicles, infrastructures, and fuels involved in these systems. Energy inputs are quantified as well as greenhouse gas and criteria air pollutant outputs. Inventory results are normalized to effects per vehicle-lifetime, VMT, and PMT. Current results show that total energy and greenhouse gas emissions increase by as much as 1.6X for automobiles, 1.4X for buses, 2.6X for light rail, 2.1X for heavy rail, and 1.3X for air over operation. Criteria air pollutant emissions increase up to 30X for automobiles, 7X for buses, 10X for light rail, 29X for heavy rail, and 9X for air. This working paper is superceded by UCB-ITS-DS-2008-1, the Ph.D. dissertation of Mikhail Vin Chester.

The passenger transportation modes of auto, bus, heavy rail, light rail and air are critical systems relied upon for business and leisure. When considering their environmental effects, most studies and policy focus on the fuel use of the vehicles, and ignore the energy and other resource inputs and environmental outputs from the life cycles of necessary infrastructures, fuels, and vehicles. The goal of this project is to develop comprehensive life-cycle assessment (LCA) models to quantify the energy inputs and emissions from autos, buses, heavy rail, light rail and air transportation in the U.S. associated with the entire life cycle (design, raw materials extraction, manufacturing, construction, operation, maintenance, end-of-life) of the vehicles, infrastructures, and fuels involved in these systems. Energy inputs are quantified as well as greenhouse gas and criteria air pollutant outputs. Inventory results are normalized to effects per vehicle-lifetime, VMT, and PMT. Current results show that energy and greenhouse gas emissions increase by as much as 1.3X for automobiles, 1.4X for buses, 2.6X for light rail, 2.1X for heavy rail, and 1.3X for air. Criteria air pollutant emissions increase up to 25X for automobiles, 7X for buses, 220X for light rail, 98X for heavy rail, and 11X for air. This working paper is superceded by UCB-ITS-DS-2008-1, the Ph.D. dissertation of Mikhail Vin Chester.

Goal, Scope and Background. LEED (Leadership in Energy and Environmental Design) is a scoring system that evaluates the environmental friendliness of,buildings. It is composed of 69 credits, each one providing a score of one (i.e., one point) if implemented. However, since each credit does not always provide the same type and magnitude of benefits for the environment, a higher rating is not always synonymous with lower impacts. The goal of this paper is to evaluate the actual extent of the benefits and burdens of LEED, identify the critical credits and develop a new scale that will correct these miscorrelations. Methods. The various LEED credits are qualitatively analysed. It is possible to quantify the actual outcomes and thus perform a lifecycle assessment (LCA) on 45 credits applied to an actual California office building. This allows comparing the benefits of the different credits among each other. Commuting of the employees is included in the system. The LCA is performed with the help of SimaPro 7, combining the ecoinvent 1.2 inventory database and the impact assessment methodology IMPACT 2002+ v2.1, adapted to North America. Impacts are evaluated for human health, ecosystems quality, climate change, and resource consumption. Impacts of the different credits are aggregated in one indicator to allow the design of a new scoring system that assigns to the different credits an amount of points (i.e., a score) that are related to the actual benefits. A school and a residential building are also modeled in order to perform a sensitivity study. Results and Discussion. Operation, especially employee commuting and electricity consumption, dominates the impacts associated with the building. It appears that waste generation have limited but not negligible impacts, whereas water consumption has small impacts. Since the building is situated in California, heating is not an important source of impacts. As a result, credits that provide the most environmental benefits are the ones geared toward increasing the fraction of green electricity, reducing energy consumption, reducing employee commuting, and increasing waste recycling, along with the ones favoring the reuse and recycling of the building structure. The ones targeting reduction of water and land use, and recycling content in the furniture appear to be less beneficial. The scores of the different LEED credits range from -128 to 606. Negative credits are due to credits that lead to more burdens than benefits, for example, the one requiring the construction of a multifloor parking lot (with a score of -128). The most beneficial credit (with a score of 606) is the one requiring that electricity comes from at least 50% green power. Conclusions and Outlook. Comparing the new scale with the observations on site shows that the LEED credits actually implemented are not always the most beneficial for the environment. This issue should be addressed in order to make LEED more efficient. The proposed rating system should help correct these discrepancies. The amount of reduction in employee commuting that the related credits really achieve, actual impacts of land and water use, along with the benefits of improved indoor air quality are among the main future challenges of the present study.