13,018 research outputs found

    Adjusting ITE’s Trip Generation Handbook for Urban Context

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    This study examines the ways in which urban context affects vehicle trip generation rates across three land uses. An intercept travel survey was administered at 78 establishments (high-turnover restaurants, convenience markets, and drinking places) in the Portland, Oregon, region during 2011. This approach was developed to adjust the Institute of Transportation Engineers (ITE) Trip Generation Handbook vehicle trip rates based on built environment characteristics where the establishments were located. A number of policy-relevant built environment measures were used to estimate a set of nine models predicting an adjustment to ITE trip rates. Each model was estimated as a single measure: activity density, number of transit corridors, number of high-frequency bus lines, employment density, lot coverage, length of bicycle facilities, presence of rail transit, retail and service employment index, and intersection density. All of these models perform similarly (Adj. R2 0.76-0.77) in estimating trip rate adjustments. Data from 34 additional sites were collected to verify the adjustments. For convenience markets and drinking places, the adjustment models were an improvement to the ITE’s handbook method, while adjustments for restaurants tended to perform similarly to those from ITE’s estimation. The approach here is useful in guiding plans and policies for a short-term improvement to the ITE’s Trip Generation Handbook. The measures are useful for communities seeking to develop local adjustments to vehicle trip rate estimates, and all could be calculated from spatial data available in most locations. The paper concludes with a discussion on what long-term improvements to the ITE’s Trip Generation Handbook might entail, with further implications in planning and practice

    Gasoline prices and road fatalities: international evidence

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    This study utilizes data for 144 countries from 1991 to 2010 to present the first international estimates of the gasoline price elasticity of road fatalities. We instrument each country’s gasoline price with that country’s oil reserves and the yearly international crude oil price to address potential endogeneity concerns. Our findings suggest that the average reduction in road fatalities resulting from a 10% increase in the gasoline pump price is in the order of 3%–6%. Around 35,000 road deaths per year could be avoided by the removal of global fuel subsidies

    Population characteristics and habitat suitability of Asian elephants (Elephas maximus Linnaeus, 1758) in the Khao Yai National Park, Thailand

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    The aim of this study was to investigate the population and habitat of wild elephants in the Khao Yai National Park, to provide elephant population densities using the line transect method. Habitat suitability was also assessed based on the data obtained from the location of the species during monthly ranger patrol across the park area, with the rate of dung decay used for population calculation. The population structure and age class were studied by direct observation to estimate the population trend. On the basis of 116 systematic transect lines that were 2 km in length and separated by 500-m intervals, a total of 1,209 elephant dung piles were found in more than 213.20 km. The analysis of the combined data showed that the dung density was 531.49 dung piles/km 2, with a decay rate of 0.0039 dung piles/day based on 56 dung piles checked every 7 days. The annual data showed that the population density was 0.15 individuals/km 2. The population structure comprising  calf:juvenile:subadult:adult was 1: 1.09:1.14:2.10; the sex ratio of adult male to adult female elephants was 1:1.10; and the ratio of reproductive ability among adult females, juveniles, and calves was 1.00:0.99:0.90. The combined data also showed that the main environmental factor affecting the presence of the animals was salt lick sites. The pooled data analysis found that the habitat most suitable for the elephants covered an area of 220.59 km 2. The habitat suitability, based on the dry season appearance data, covered an area of 258.64 km 2, whereas during the wet season, it covered an area of 517.45 km 2. As the most suitable habitat for elephants appears around the park boundary, habitat improvements for wild elephants should address the central areas of the national park. A greater emphasis should be placed on creating salt licks, being far from human activity sites

    Marginal abatement cost curves (MACCs): important approaches to obtain (firm and sector) greenhouse gases (GHGs) reduction

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    The study aims to identify appropriate methods that can help organisations to reduce energy use and emissions by using an effective concept of sustainability. In different countries, estimates of marginal abatement costs for reducing GHG emissions have been widely used. Around the world, many researchers have focused on MACCs and reported different results. This may due to different assumptions used which in turn lead to uncertainty and inaccuracy. Under these circumstances, much attention has been paid to the need for the role of MACC in providing reliable information to decision makers and various stakeholders. By reviewing the literature, this paper has analysed MACCs in terms of the role of different approaches to MACCs, representations of MACCs, MACC applications, pricing carbon, verification, and sectors analysis for energy and emissions projections. This paper concludes that MACCs should depend on actual data to provide more reliable information that may assist (firms and sectors) stockholders to determine what appropriate method for reducing emission

    The limits of technology: achieving transport efficiency in developing nations

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    Emissions from the transport sector represent the fastest growing source of greenhouse gas emissions. There is little prospect that this situation will be resolved with a single technological fix. As developing nations quickly move to catch up with the motorisation levels of developed nations, the sheer number of private vehicles on the roadways will overwhelm any advances made by cleaner fuels. By the year 2030, there is projected to be more vehicles in the developing world than in developed nations. However, most developing cities today still have the basis for a more sustainable future. Public transport and non-motorised transport (walking and cycling) still command a dominant share of travel in developing cities. Thus, a key objective for local and international initiatives is to preserve existing mode shares. Unfortunately, most investment in reducing transport emissions relies exclusively upon achieving costly reductions only through fuel and propulsion system technologies. Bogotá (Colombia) represents one of the best examples of a city that has developed a package of complementary measures to substantially reduce vehicle emissions and congestion. Bogotá’s implementation of a high-quality bus rapid transit (BRT) system, bicycle infrastructure, pedestrian improvements, car-free events, and auto restriction measures all have contributed to an urban transformation in a period of just a few years. Initial projections of greenhouse gas reductions during the first 30 years of the BRT system’s operation indicate reductions of approximately 14.6 million metric tons of CO2 equivalents. This research presents a framework for evaluating the greenhouse gas emission reductions in the transport sector. This framework highlights three principal areas of emission reduction potential: 1.) Mode share (behaviour); 2.) Distance travelled (land-use/design); and 3.) Fuel efficiency (technology). Only by addressing all three components an optimum transport energy path can be achieved

    Cities, traffic, and CO2: A multidecadal assessment of trends, drivers, and scaling relationships

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    Emissions of CO2 from road vehicles were 1.57 billion metric tons in 2012, accounting for 28% of US fossil fuel CO2 emissions, but the spatial distributions of these emissions are highly uncertain. We develop a new emissions inventory, the Database of Road Transportation Emissions (DARTE), which estimates CO2 emitted by US road transport at a resolution of 1 km annually for 1980-2012. DARTE reveals that urban areas are responsible for 80% of on-road emissions growth since 1980 and for 63% of total 2012 emissions. We observe nonlinearities between CO2 emissions and population density at broad spatial/temporal scales, with total on-road CO2 increasing nonlinearly with population density, rapidly up to 1,650 persons per square kilometer and slowly thereafter. Per capita emissions decline as density rises, but at markedly varying rates depending on existing densities. We make use of DARTE's bottom-up construction to highlight the biases associated with the common practice of using population as a linear proxy for disaggregating national- or state-scale emissions. Comparing DARTE with existing downscaled inventories, we find biases of 100% or more in the spatial distribution of urban and rural emissions, largely driven by mismatches between inventory downscaling proxies and the actual spatial patterns of vehicle activity at urban scales. Given cities' dual importance as sources of CO2 and an emerging nexus of climate mitigation initiatives, high-resolution estimates such as DARTE are critical both for accurately quantifying surface carbon fluxes and for verifying the effectiveness of emissions mitigation efforts at urban scales.https://doi.org/10.1073/pnas.1421723112Published versio

    What is a system? NASA's phased project description

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    NASA phase A and B projects are addressed. The Phase A study is the preliminary analysis of a space concept. These concepts could have come from a pre-Phase A study or from other sources within or external to NASA. The majority of concepts that are studied at MSFC are assigned by NASA Headquarters and funded accordingly. The overall program schedule depicts important milestones that establish the start and finish dates of each study phase, including design, development, launch, and operations. The Phase B of the project consists of the refinement of preliminary requirements, cost estimates, schedules and risk assessments prior to starting final design and development. The goal of a concept definition activity is to determine the best and most feasible concept(s) that will satisfy the mission and science requirements

    Market Power, Multimarket Contact and Pricing: Some Evidence from the US Automobile Market

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    Multimarket contact is perceived to be one of those factors, which can facilitate and sustain implicit collusive (cooperative) arrangements. This paper attempts to develop new approaches to study the interdependence of firm behaviour across markets, especially in the context of differentiated products industries. I analyse the principle of conducting a test of the mutual forbearance hypothesis, and its application using particular data. The multimarket contact effects are studied within a structural oligopoly model for differentiated products for the US automobile market on the basis of the aggregate product-level data for 2001-2003. Some support has been found that multimarket contact may influence competition in the automobile market and increase the firms' strategic interdependence. This effect is, however, difficult to disentangle from the effect of the market concentration in the US automobile market (dominance of the market by the American Big Three) on the firm behaviour, which could also facilitate collusion. In other words, it is difficult to argue whether coordination is due to market concentration, or due to multimarket contact, or both. Concentration is argued to foster the slack, which is transferred through the multimarket contact. --multimarket contact,collusion,automobile industry,test for non-nested hypothesis,menu test,structural oligopoly models
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