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Dockless bikeshare systems show potential for replacing traditional dock-based systems, primarily by offering greater flexibility for bike returns. However, many cities in the US currently regulate the maximum number of bikes a dockless system can deploy due to bicycle management issues. Despite inventory management challenges, dockless systems offer two main advantages over dock-based systems: a lower (sometimes zero) membership fee, and being free-range (or, at least free-range within designated service areas). Moreover, these two advantages may help to solve existing access barriers for disadvantaged populations. To date, much of the research on micro-mobility options has focused on addressing equity issues in dock-based systems. There is limited knowledge of whether, and the extent to which dockless systems might help mitigate barriers to bikeshare for disadvantaged populations. Using San Francisco and Los Angeles as case studies, because both cities have both dock-based and dockless systems running concurrently, the research team quantified bikeshare service levels for communities of concern (CoCs) by analyzing the spatial distribution of service areas, available bikes and bike idle times, trip data, and rebalancing among the dock-based and dockless systems. They found that dockless systems can provide greater availability of bikes for CoCs than for other communities, attracting more trip demand in these communities because of a larger service area and frequent bike rebalancing practices. More importantly, they noticed that the existence of electric bikes helps mitigate the bikeshare usage gap between CoCs and other tracts. Besides the data analyses for bikeshare trips, the research team also studied the spatial distribution of online suggested station locations and find that the participants’ desired destinations for work/school purposes have not been covered to the same extent in CoCs as in other communities. The results provide policy insights to local municipalities on how to properly regulate and develop dockless bikeshare systems to improve mobility equity.View the NCST Project Webpage

Bikeshare programs are increasingly popular in the United States, and they are an important part of sustainable transportation systems. They offer an important alternative mode choice for many types of last mile trips. Most of the current research on bikeshare focuses on bikeshare benefits (e.g., how to replace auto trips with bike trips and reduce greenhouse-gas emissions) and bikeshare system management (e.g., bike repositioning between stations). Far less attention has been paid to the programmatic potential for providing greater access to jobs and essential services for underserved communities. To date, there is virtually no quantitative research aimed at designing bikeshare systems for underserved communities. The authors develop a new spatial index that identifies bikeshare station locations exhibiting a high potential for providing service for underserved communities. The index can: 1) facilitate the identification of priority areas for bikeshare investment based on current infrastructure and the potential for increased job or essential service access; 2) inform the siting of bikeshare stations and investment in bike infrastructure to better assist underserved populations, and finally 3) provide an estimate of the potential for improved job and social services access via bike‐to‐transit.View the NCST Project Webpage

This report examines the ability of existing and proposed affordable housing policies to align with sustainable transportation goals in California. First, the authors compare the ability of Low Income Housing Tax Credit (LIHTC), Redevelopment and inclusionary funded projects to locate in neighborhoods with transit access to employment versus market rate production in the same period. The authors find tax credit funded units outperform market rate production with respect to job accessibility via transit, and the authors attribute this to the scoring criteria of California’s tax credit allocating body, the Tax Credit Allocation Committee (TCAC). However, the authors find this may have come at the cost of concentrating new affordable housing in areas with higher poverty rates. At the federal level, the authors measure how a change in the determination of maximum payouts for Section 8 housing vouchers, known as Fair Market Rents (FMRs), alters the ability of voucher holders to access transit and jobs rich neighborhoods. The results show that changing to “Small Area” FMRs, which are determined at the ZIP code scale, dramatically improves voucher holders’ access to jobs rich neighborhoods. This benefit comes at the cost of nearly eliminating voucher accessibility in neighborhoods that are currently accessible. And finally, at the state level, an analysis is conducted to determine if California’s emphasis on promoting affordable housing in transit and jobs rich neighborhoods is increasing the cost of affordable housing development. The modeling results indicate that affordable housing near transit stops is not significantly more expensive, but that costs increase slightly for projects in jobs rich neighborhoods. Participation in the state’s Transit Oriented Development (TOD) housing program does not significantly impact costs. The results of this research are intended to inform policy makers at every level of government on how best to continue to integrate transportation and housing policies without sacrificing the primary purpose of affordable housing policies: to house people.View the NCST Project Webpage

Future air pollution emissions in the year 2030 were estimated for the San Joaquin Valley (SJV) in central California using a combined system of land use, mobile, off-road, stationary, area, and biogenic emissions models. Four scenarios were developed that use different assumptions about the density of development and level of investment in transportation infrastructure to accommodate the expected doubling of the SJV population in the next 20 years. Scenario 1 reflects current land-use patterns and infrastructure while scenario 2 encouraged compact urban footprints including redevelopment of existing urban centers and investments in transit. Scenario 3 allowed sprawling development in the SJV with reduced population density in existing urban centers and construction of all planned freeways. Scenario 4 followed currently adopted land use and transportation plans for the SJV. The air quality resulting from these urban development scenarios was evaluated using meteorology from a winter stagnation event that occurred on December 15, 2000 to January 7, 2001. Predicted base-case PM2.5 mass concentrations within the region exceeded 35 μg m-3 over the 22-day episode. Compact growth reduced the PM2.5 concentrations by approx. 1 µg m-3 relative to the base-case over most of the SJV with the exception of increases (approx. 1 µg m-3) in urban centers driven by increased concentrations of elemental carbon (EC) and organic carbon (OC). Low-density development increased the PM2.5 concentrations by 1-4 µg m-3 over most of the region, with decreases (0.5-2 µg m-3) around urban areas. Population-weighted average PM2.5 concentrations were very similar for all development scenarios ranging between 16 and 17.4 µg m-3. Exposure to primary PM components such as EC and OC increased 10-15% for high density development scenarios and decreased by 11-19% for low-density scenarios. Patterns for secondary PM components such as nitrate and ammonium ion were almost exactly reversed, with a 10% increase under low-density development and a 5% decrease under high density development. The increased human exposure to primary pollutants such as EC and OC could be predicted using a simplified analysis of population-weighted primary emissions. Regional planning agencies should develop thresholds of population-weighted primary emissions exposure to guide the development of growth plans. This metric will allow them to actively reduce the potential negative impacts of compact growth while preserving the benefits.

Diesel-electric locomotives used by U.S. freight railroads are relatively low emitters of criteria air pollutants and greenhouse gases when compared to competing modes; however, the continuous growth in goods movement is cause for concern as locomotive emissions may grow. Railroads only account for a small fraction of all mobile source emissions, but the concentration of emissions along rail facilities raises questions about equity, in particular environmental justice, and the relative benefits of competing modes of goods movement. This paper provides a synthesis and review of current data and methods used to account for regional locomotive activity. Understanding data limitations and methodological issues at the regional scale provides a starting point for development of more spatially detailed locomotive emission models. Methods developed by EPA and the California Air Resources Board are considered. It is found that each method produces very different results and is inadequate for use at the regional (or smaller) spatial scale. Problems arise from activity measures that ignore differences in geography and freight rail services between regions or depend on detailed operational data that are no longer available. While detailed activity data do exist, they are not always available because they are owned by private railroads. New methods should minimize the use of detailed or confidential railroad data yet still be sensitive to local factors. Fuel based methods provide the most hope, but greater cooperation between regulatory agencies and railroads is required.

Markets can play a key role in mitigating the effects of climate change by providing added flexibility, allowing emissions reductions to occur at a lower cost while maintaining a set level of emissions reductions. With careful regulatory design, both industry and consumers can benefit from low costs. We review the state of carbon trading globally and in the United States, the West and California. New policies and regulations related to AB32, which mandates reductions in California’s greenhouse-gas emissions to 1990 levels by 2020, are beginning to take shape. California has a unique opportunity to establish a new ethos for carbon trading by acknowledging unavoidable mitigation costs, and by designing a market-based solution that is fair, equitable and transparent, and protects the most vulnerable members of society.

With the passage of the Global Warming Solutions Act of 2006 (AB32), California has begun an ambitious journey to reduce in-state GHG emissions to 1990 levels by 2020. Under the direction of executive order S-20-06, a mandated Market Advisory Committee (MAC) charged with studying market-based mechanisms to reduce GHG emissions, including cap and trade systems, has recommended taking an “upstream” approach to GHG emissions regulation, arguing that upstream regulation will reduce administrative costs because there are fewer agents. In this paper, we argue that, the total costs to society of a GHG cap and trade scheme can be minimized though downstream regulation, rather than the widely proposed upstream approach. We propose a household carbon trading system with four major components: a state allocation to households, household-to-household trading, households to utility company credit transfers, and utility companies to government credit transfers. The proposed system can also be considered more equitable than carbon taxes and upstream cap and trade systems to control GHG emissions from residential energy use and is consistent with AB32.

Emission inventory models are a key input to regional air quality plans, called State Implementation Plans (SIPs) in the US. These plans frequently include emissions caps, or “budgets,” to which transportation system emissions must be compared. When emissions models and vehicle fleet-related planning assumptions change substantially, but for a variety of reasons the State Implementation Plan and its emissions budgets do not, a mismatch arises. The SIP Currency approach addresses problems that arise when the latest emissions and transportation modeling tools and planning assumptions are used to estimate on-road vehicle emissions, but the resulting estimates are compared to outdated emissions targets. Translating emissions estimates into the currency of emissions estimates included in older air quality plans provides a way to ensure continued improvement in air quality while preventing unintended disruption of transportation planning. The article illustrates how carbon monoxide, volatile organic compound and oxides of nitrogen emissions may be translated into the currency of outdated emissions models.

For air quality dispersion models, mobile source emissions, including both link- and traffic zone-level emissions, must be disaggregated into grid cells. Current gridding methods assign all traffic analysis zone level emissions to the single grid cell containing the TAX centroid. In this study, we propose a new approach for disaggregating traffic analysis zone-level emissions using a bicubic spline interpolation function and activity and roadway densities. The new approach, which betters replicates the heterogeneity associated with travel activities, distributes zone-level emissions into the grid cells contained within the zone boundary. When results are compared to the current methods, we find that fewer grid cell misallocations occur and that emissions from TAZs overlapping multiple grid cells are apportioned correctly. The gridded emission inventory developed using the new approach will result in better data inputs for air quality modeling, and in particular can significantly improve transportation conformity analysis.

With a projected rise in the number of elderly, most of whom have also relied primarily on the private automobile for their mobility, it is likely that future adaptations in vehicle design will be linked in some part to the physical infirmities often faced by the elderly. This paper offers a bridge between medical research on the physical impairments of the elderly and automobile design and driving safety. We describe recent findings on the driving-related physical and cognitive impairments faced by the elderly. We then propose two major types of vehicle design and infrastructure adaptations: (1) modifications for private vehicles, and (2) intelligent technology and support services for private vehicles, which can help to minimize the driving-related effects of these impairments. For example, we present a range of modest vehicle design adaptations for components such as seats and doorways, handles, knobs, and steering wheels, and seat belts. We find that many of these improvements can be made to standard passenger vehicles with little additional design effort, and that the adaptations should also increase overall vehicle marketability. Finally, we argue that while most, if not all, of our proposed adaptations would be made to largely benefit the elderly, they will nevertheless support and improve driving across all age groups.

To more accurately predict hourly running stabilized link volumes for emissions modeling, a new method was recently developed that disaggregates the period-based model link volumes into hourly volumes using observed traffic count data and multivariate multiple regression (MMR). This paper examines the MMR methodology with clustering and classification analyses to account for spatial variability and to accommodate model links that do not have matching observed traffic count data. The methodology was applied to data collected in the South Air Basin. The spatial analysis resulted in identifying five clusters (or 24-h profiles) for San Diego and two clusters for Los Angeles. The MMR models were then estimated with and without clustering. For San Diego, the disaggregated model volumes with clustering were much closer to the observed volumes than those without clustering, with the exception of the a.m. period. For most hours in Los Angeles, the predicted volumes with clustering were only slightly closer to the observed volumes than those predicted without clustering, suggesting that spatial effects are minimal in Los Angeles (i.e., that 24-h volume profiles are fairly similar throughout the region) and clustering is not necessary. Finally, two classification models, one for San Diego and one for Los Angeles were developed and tested for network link data that does not have matching observed count data. The results indicate the procedure is relatively good at predicting cluster assignment for the unmatched location for Los Angeles but less accurate for San Diego.

In general, the limitations of the current California vehicle emissions inventory models can be summarized as:- There is no direct connection between the regional emissions inventory model and the gridded emissions model. Separate model runs must be processed to develop regional emissions inventories and gridded emissions.- The emission estimates from the regional emissions inventory model and the gridded emissions model are not in agreement.- The regional emissions inventory model is not directly connected to the transportation forecasting models.- The gridded emissions model has an inappropriate interface between the transportation data and the emissions rates.The purpose of this study is to develop a new transportation and emission interface model. This requires advancing the knowledge with respect to gridded emissions calculations, as well as improving current spatial computations of emissions. Oriented at the grid cell level, the new model will establish a direct connection between regional emissions inventories for conformity and gridded emissions for airshed dispersion modeling.The new model will be able to use transportation data from the standard four-step travel demand models, and emissions rates from EMFAC2000 or a set of newly developed link-based facility-specific CAMP running exhaust emissions rates. EMFAC2000 represents the latest understanding of mobile emissions development. Its algorithm and methodologies on basic emission rates development, driving cycle adjustment, speed adjustment factors, vehicle fleet age distribution, and traffic activity data significantly improve the emissions inventory estimates. Alternatively, the link-based CAMP emissions rates disaggregate travel activities by facility type, so that emissions rates will more closely represent link-level emissions than previously available. When developing emissions inventories, both transportation data and emissions rates will sit at the link level. This will ensure that transportation data and emissions rates in the new model sit at the same level of interface, and the model will be methodologically sound.The implementation of the new model will be flexible with the ability to model areas ranging from county level to individual project level. The spatial and temporal emissions evaluation can be conducted at any level of the model's implementation.The proposal is organized into five chapters. Chapter 2 provides a broad overview of related research in transportation and emissions modeling. A summary of the available transportation, emissions rates, and emissions inventory models is presented, and their strengths and weaknesses are discussed. Model development trends are discussed at the end of the chapter.Chapter 3 provides an in-depth evaluation of the two emissions inventory models widely used in California (BURDEN7G and DTIM3). The strengths and weaknesses of each model are discussed. The chapter concludes with a summary of the challenges and motivations behind the proposed new interface model.Chapter 4 presents the design of the new transportation and emission interface model. The model structure, required transportation data, emissions rates, and the interface of transportation data and emissions rates are discussed. Finally, Chapter 5 discusses the strengths and weaknesses of the new model.

This report evaluates the costs and benefits of home-based telecommuting. Combining empirical data from the literature with a Monte Carlo simulation technique, a distribution of cost-benefit ratios is produced from three perspectives: the employer, the telecommuter, and the public sector.... Depending on the underlying assumptions, the results indicate that telecommuter benefit-cost ratios are generally above one if the employer bears the majority of the equipment cost burden. ...Even when parking and office space benefits are included, productivity lies at the heart of the telecommuting cost-benefit analysis from the employer's perspective, and in almost all cases, the employer's case relies on some assumed maintenance or increase in productivity as the primary benefit. It is also shown that the potential for office and parking space benefits are high, although these benefits remain somewhat questionable. ...Based on our analysis, we conclude that the public sector air quality and construction avoidance benefits remain somewhat questionable based on the current knowledge, and difficult to justify.... Keywords: telecommuting, cost-benefit analysis, simulation, telecommunication

This literature review has been prepared to synthesize and assess previous small-scale economic evaluations of telecommuting. These small-scale studies can be categorized as telecommuting pilot projects that take into account telecommuter and employer costs and benefits. (The reader is referred to a 1998 review of macro-scale telecommuting literature by Shafizadeh et al.). In this report, four studies are selected and examined as representing the state of practice regarding methodology and assumptions. The report identifies common inputs, critical assumptions, and limitations of these works. Finally, the major findings of each study are presented and compared to claims found in promotional literature. Among the primary findings of this review is the conclusion that few pilot evaluations contained cost-benefit results. Nonetheless, the results that are available supplement the macro-scale studies and furnish a variety of empirical values that are essential in complete cost-benefit analyses.

This document is intended for use by agencies that sponsor transportation projects as a supplement when evaluating the potential local level carbon monoxide (CO) impacts of a project. It contains an outline of the major steps involved in analyzing project-level CO impacts using the CO Protocol. It also includes examples illustrating the use of the Protocol. The Protocol provides a structure for documenting project-level air quality analysis that is accepted by regulatory agencies.

Recent studies on real-world automobile emissions measurements have not adequately addressed the question of whether driving style affects emission levels. In this study, we hypothesized that given the same experimental conditions and a random selection of drivers, the variability associated with individual driving styles (e.g. intensity or duration of acceleration events) would produce statistically significant differences in measured emissions. To test this driver variability hypothesis, we conducted a field study on 24 drivers in a single vehicle on a specified route under low traffic conditions using on-board exhaust emission and engine operating data analyzers and tested for statistically significant differences in CO and NOx emissions between drivers. Our data show significant (95% level) variations in carbon monoxide (CO) and oxides of nitrogen (NOx) emissions among the 24 drivers under driving conditions where we have controlled for driving route, traffic density and vehicle type. Since the ANOVA tests showed significant differences in emissions between drivers but the frequency of driving modes were very similar, this suggests that the intensity of vehicle operation within a give mode, not the modal frequency, explains the emissions variability between drivers.

This paper examines longitudinal mode use trends using four waves of the Puget Sound Transportation Panel. The analysis is conducted using generalized estimating equations for model estimation. In addition to examining mode use frequencies over time, we also consider mode use trends conditioning on household income and lifecycle stage. As expected, results indicate an overall increase in the number of worktrips made between 1989 and 1993 and these trips were marked by increasing use of single occupancy vehicles. The full parameters of the model were also to estimate the rate of increase in terms of percentage increase and their confidence intervals. Results indicate that the mean number of worktrips made by driving alone significantly increased from wave 1 to wave 4; with a 95% C.I. the rate of percent increase was estimated between 8.2 and 24.5%. The ranges for rates of change in high occupancy vehicle modes and non-motorized worktrip frequencies overlap with the range for single occupancy vehicle rate of change, and thus, it cannot be said that rate of change for the high occupancy modes was significantly different from the single occupancy rates of change. The rate of change in the mean frequency for the high occupancy¯transit mode is not only below the range for single occupancy vehicle trips but also suggests, with 95% confidence, the rate of percent decrease was between 2.88 and 44.0%.

Airborne particles are separated according to their electrical mobilities using a microfabricated corona ionizer and separator electrodes. Oleic acid particles with sizes ranging from 30 to 300 nm are used to characterize the device. They are generated using a TSI 3075 constant output atomizer. These particles are electrically charged by a microfabricated corona ionizer, and the resultant particle electrical mobility is a function of the size of the particle. A varying dc potential difference of 0-2 kV across the separator electrodes selects charged particles of various electrical mobilities. These separated particles are subsequently counted using a TSI 3025A Condensation Particle Counter. The device demonstrated its ability to separate particles between 50 and 130 nm into five distinct size bins. The operational flow rate is 0.5 L/min, and the micropin-between-planes corona ionizer operates at 1.3 kV with 7 [mu]A. The theoretical and experimental electrical mobilities of the particles are compared. [2008-0091] Index Terms--Aerosol instrumentation, corona ionizer, particle electrical mobility, particle separation.

A microfabricated corona ionizer is developed for miniaturized air particle monitoring instruments. Peek's breakdown criterion and Warburg's Law are used to calculate the required electrode geometries. Single mask electroplating is employed as the microfabrication technique. Devices with discharge pin radius of 20 [micro]m and interelectrode spacing of 1.4, 1.8, 2.0, and 2.2 mm are fabricated and tested. The inception voltages in the range from 1.4 to 2 kV are achieved without substrate breakdown. It consumes relatively low power at 150 mW or less. Corona charging currents of more than 50 [micro]A were achieved before streamers break down. The experimental results also demonstrated the nondependency of the inception voltage on the pin's radius of curvature so long as it is significantly smaller than the interelectrode spacing. There is only one value of inception voltage for each given interelectrode spacing ( 1.4 to 2.2 ram) with the pin's radius of curvature ranging from 10 to 200 [micro]m. This implies that strict dimensional control is not required in the microfabrication process in order to ensure the same inception voltage for each device. [2007-0152] Index Terms--Avalanche, corona, discharge, electroplating, inception, ionizer, microfabricated, plasma, streamer.

A benefit-cost analysis framework is developed for an added bicycle phase at an existing signalized intersection. The intersection operates with both high volume levels of both vehicles and bicycles. As part of this study, traffic volume counts were collected and average vehicle delays computed and extrapolated to represent a full year. The costs and disbenefits included in the analysis were construction costs and changes in operating costs, safety, and vehicle capacity. We find that the overwhelming benefits associated with increased bicycle safety, which can be seen as a decrease in the number of bicycle-vehicle conflicts, outweigh all costs and the disbenefits associated with increased vehicle delay. Externalities such as the change in vehicle emissions are also examined but are not included in the benefit-cost ratio. We find that the change in emissions associated with increased vehicle delay is relatively minor. CE Database keywords: Cost-benefit; Bicycle improvement; Bicycle phasing; Signalized intersection.

The EPA specifies that level-of-service D intersections must undergo detailed microscale carbon monoxide modeling using the recommended software such as CAL3QHCr, which requires an in-depth knowledge of microscale dispersion modeling of pollutants. In this study, a new statistical framework is introduced that is intended to replicate the microscale modeling results achieved with CAL3QHCr. The new framework provides an important means for assessing air quality impacts during the design phase of a transportation project, without having to acquire the modeling skills and/or dispersion modeling knowledge necessary to execute CAL3QHCr. To develop the framework, approximately 23,000 CAL3QHCr simulation scenarios were generated by varying the input values of the major design and dispersion modeling factors. The input values, together with the corresponding output values of CAL3QHCr simulations, were used to specify a statistical model for predicting carbon monoxide concentrations. The statistical model was then validated using field meteorological conditions for five cities in California. The study results show that the proposed model can be easily and reliably used by traffic engineers to predict potential carbon monoxide exceedances at the planning stages for transportation projects.