Long-memory characteristics of urban roadside air quality

Carbon monoxide is a major contributor to air pollution in urban cities, particularly at the roadside. Hourly, monthly and seasonal mean carbon monoxide concentration data are collected from a roadside air monitoring station in Hong Kong over 7-years. The station is a few metres from a major intersection surrounded by tall buildings. In particular, hourly patterns of concentrations on different days of the week are investigated. The data show that hourly carbon monoxide concentrations resemble the traffic pattern of the area and tend to be lower in the summer. Using a seasonal autoregressive integrated moving average models shows that the daily traffic cycle strongly influences concentrations. Further, it is found that urban roadside carbon monoxide monitoring data exhibits a long-memory process, suggesting that a model incorporating long memory and seasonality effects is needed simulate urban roadside air quality.     

Is road pricing effective in abating pollution? Evidence from Milan

We estimate the effect of a road pricing policy introduced in Milan in 2008 on concentrations of benzene, carbon monoxide, particulates, nitrogen dioxide and sulphur dioxide. We found a sizeable effect of the Ecopass on air quality in terms of reduction in the concentration of carbon monoxide and particulates a few days after its introduction, although this effect disappeared after only one week. We interpret these results as indicative of an inefficient policy design: motorbikes were not charged and the treated area is too limited to generate positive outcomes for the whole city. Further evidence from a natural experiment given by a temporary suspension of the charge in 2012 confirms our hypothesis on the incentives for motorbike usage.     

Policy innovations of the US intermodal surface transportation efficiency act and clean air act amendments

In combination, the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) and the Clean Air Act Amendments of 1990 (CAAA) are innovative and aggressive efforts to move US cities toward integrated transportation and air quality planning. Under these complementary laws, air quality has become a major national transportation goal. In areas with serious air pollution, air quality will be a major consideration in determining the future shape of urban transportation.This paper considers how the CAAA and ISTEA combine to provide an innovative national policy approach of interest to countries seeking to encourage sustainable development in urban centers. The CAAA mandates measurable and enforceable air quality targets. Nation-wide standards are set for acceptable levels of carbon monoxide, ground level ozone, and small particulates. ISTEA includes directions for transportation planners and decision-makers to follow to reach air quality and other goals — transportation planning must emphasize system efficiency, and for cities with severe air pollution, transportation projects are expected to contribute to cleaner air. Each urban area has flexibility in how it applies this framework to reflect its priorities and solve its problems. Strict federal sanctions provide incentives for compliance with both laws.Enactment of these laws has produced a period of transition and uncertainty as well as of challenge and opportunity for planners and elected officials. The next several years, the US will provide one national laboratory and over 100 different urban laboratories for innovative approaches to integrate transportation and environmental policies to resolve major urban problems.Abbreviations CAAA Clean Air Act Amendments of 1990 - CO Carbon monoxide - ECO Employee Commute Option - EPA US Environmental Protection Agency - HC Transportation hydrocarbons - I/M Inspections and maintenance program - ISTEA Intermodal Surface Transportation Efficiency Act of 1991 - MPO Metropolitan planning organizations - NO_x Nitrogen oxides - PPM Parts per million - PM₁₀ Small particulate matter - SIP State Implementation Plan - TIP Transportation Improvement Program - TCM Transportation control measures - VMT Vehicle miles traveled     

The impact of coordinated policies on air pollution emissions from road transportation in China

Improving air quality across mainland China is an urgent policy challenge. While much of the problem is linked to China’s broader reliance on coal and other fossil fuels across the energy system, road transportation is an important and growing source of air pollution. Here we use an energy-economic model, embedded in a Regional Emissions Air Quality Climate and Health (REACH) integrated assessment framework, to analyze the impacts of implementing vehicle emissions standards (ES) together with a broader economy-wide climate policy on total air pollution in five species and 30 Chinese provinces. We find that full and immediate implementation of existing vehicle ES at China 3/III level or tighter will significantly reduce the contribution of transportation to degraded air quality by 2030. We further show that road transport ES function as an important complement to an economy-wide price on CO₂, which delivers significant co-benefits for air pollution reduction that are concentrated primarily in non-transportation sectors. Going forward, vehicle emissions standards and an economy-wide carbon price form a highly effective coordinated policy package that supports China’s air quality and climate change mitigation goals.     

A tool for calculating aircraft emissions and its application to Greek airspace

This paper quantifies the impact of aircraft emissions on local air quality and climate change. Aircraft emissions during the cruise cycle and the landing/take-off cycle are considered. A tool is developed that computes emission values using real-time air traffic data derived from various databases. Emissions include carbon dioxide, hydrocarbons, carbon monoxide and nitrogen oxides. The overall output is a detailed ‘emissions map’ of a given territory that enables the identification of critical emission spots including routes, airports, season, aircraft type and flight category. The method can be used for real-time monitoring of airline emissions and for policy analysis. The proposed tool and resulting outputs are illustrated in the case of the Greek airport system using domestic, international and overflights. Demand volatility driven mainly by tourism and its impact on emissions is assessed.     

Identifying contributions of on-road motor vehicles to urban air pollution using travel demand model data

Ambient concentrations of pollutants are correlated with emissions, but the contribution to ambient air quality of on-road mobile sources is not necessarily equal to their contribution to regional emissions. This is true for several reasons such as the distribution of other pollution sources and regional topology, as well as meteorology. In this paper, using a dataset from a travel demand model for the Sacramento metropolitan area for 2005, regional vehicle emissions are disaggregated into hourly, gridded emission inventories, and transportation-related concentrations are estimated using an atmospheric dispersion model. Contributions of on-road motor vehicles to urban air pollution are then identified at a regional scale. The contributions to ambient concentrations are slightly higher than emission fractions that transportation accounts for in the region, reflecting that relative to other major pollution sources, mobile sources tend to have a close proximity to air quality monitors in urban areas. The contribution results indicate that the impact of mobile sources on PM₁₀ is not negligible, and mobile sources have a significant influence on both NO_x and VOC pollution that subsequently results in secondary particulate matter and ozone formation.     

Influence of vehicular traffic on urban air quality – A case study of Hyderabad,India

In the present study, impact of vehicular traffic emissions on black carbon aerosol mass concentration, trace gases and ground reaching solar radiation were analyzed during nationwide truck strike of 5–12 January, 2009 over urban environment of Hyderabad, India. A significant reduction of about 57%, 60%, 40% and 50% was observed in black carbon, particulate matter, carbon monoxide and ozone respectively during nationwide truck strike period. Results of the study are important for source apportionment of pollutants as the strike created natural laboratory for studying the impact of diesel operated trucks on urban air quality.     

A new approach for evaluating regional exposure to particulate matter emissions from motor vehicles

Exposure to fine particulate matter from vehicle exhaust is associated with increased health risk. This study develops a new approach for creating spatially detailed regional maps of fine particulate matter concentration from vehicle exhaust using a dispersion model to better evaluate these risks. The spatial extent, diurnal, and seasonal patterns of concentration fields across Los Angeles County, California are evaluated and population exposure and exposure equity by race and income are investigated. The results demonstrate how this modeling approach can create new knowledge about vehicle emissions exposure. This approach also provides a method for proactively screening out regional plans, or specific projects within these plans, that are likely to cause air quality concerns. A proactive and regional air quality assessment can identify potential problems earlier in the planning process and a wider range of solutions, saving time, money and protecting public health. The detailed concentration maps can also be used to improve the siting of regulatory air quality monitors and provide more accurate exposure data for epidemiology studies.     

Short-term,real-time prediction of the extreme ambient carbon monoxide concentrations due to vehicular exhaust emissions using transfer function-noise model

The Box–Jenkins transfer function-noise (TFN) models (Box, G.E.P., Jenkins, G.M., Reinsel, G.C., 1994. Time Series Analysis: Forecasting and Control, 3rd ed. Prentice-Hall, Englewood Cliffs, NJ.) have been used to provide short-term, real-time forecast of the extreme carbon monoxide for an air quality control region (AQCR) comprising a major traffic intersection in the centre of the capital city of Delhi. The time series of the surface wind speed and ambient temperature have been used as “explaining” exogenous variables in the TFN models. When compared with the results of univariate ARIMA model of the endogenous series, the forecast performance is found to improve with the inclusion of the wind speed as input series; however, no significant improvement is observed in the forecast with the inclusion of temperature as input series.     

An assessment of pollutant emissions due to air traffic at Nikola Tesla International Airport,Belgrade, and the link between local air quality and weather types

The assessment of local air pollution due to air traffic is an important issue from the standpoint of human health. An advanced approach using a landing and take-off cycle method is employed to assess emissions of nitrogen oxides (NO_x), carbon monoxide (CO), hydrocarbon (HC), and sulphur oxides (SO_x). Emissions of both volatile and non-volatile particulate matter are estimated using the new First-Order Approximation methodology. As synoptic situations (weather) determine the transport of pollutants in the air as well as their scavenging, the weather type for each day is classified for the study period (2008–2015).Due to a significant increase in air traffic at Nikola Tesla International Airport, Belgrade, in the last eight years, emissions of all considered pollutants have also increased. Emissions of NO_x and CO were the highest (totals for eight years were 2976.03 and 2875.66 tons, respectively). An analysis of weather types showed that the most frequent were warm, dry, anticyclones (AWD) and cyclones (low-pressure systems) including the passage of a cold front (CCF). The frequency of occurrence of AWDs and CCFs was 28.3% and 21.6%, respectively. An AWD is very unfavourable from the viewpoint of local air pollution, especially during the cold part of year, due to a shallow temperature inversion and fog formation in the morning confining the pollutants to the emission location for a longer time span. CCFs are also adverse due to the prevailing westerly and north-westerly winds that transport pollutants toward the city.     

Testing the limits of TSM: the 1984 Los Angeles Summer Olympics

This paper analyzes the impact of the transportation system management (TSM) program employed during the 1984 Los Angeles Summer Olympics. Two issues are examined. First, the impact of the various elements of the TSM program on transportation system performance is measured by conducting a series of traffic simulation studies. The results show that TSM was an important contributing factor in the favorable traffic conditions experienced during the Olympics. Second, the potential of employing TSM as a long-term transportation policy strategy is assessed. It is concluded that the travel behavior changes that occurred in response to the TSM program were unique and short-term. Under ordinary circumstances, incentives do not exist to induce changes of the magnitude observed during the Olympics.     

Short trips: An opportunity for reducing mobile-source emissions?

This paper examines how conversion of automobile trips of less than 3 miles to other transportation modes reduces emissions. Short trips contribute disproportionately to emissions because of cold starts. An analysis is conducted of short-trip behavior across the US using the 1995 Nationwide Personal Transportation Survey. The data is used to develop likely scenarios of mode conversions for short trips, which are then applied to estimate emission savings using MOBILE6 cold start and running emission factors for volatile organic compounds, nitrogen oxides, carbon monoxide, and carbon dioxide. The results suggest that reducing short auto trips would modestly reduce mobile source air pollution, but emission reductions are high compared to most federally-funded surface transportation interventions aimed at improving air quality. Enhanced the community pedestrian environment to encourage short trip mode conversion also produces co-benefits such as increased physical activity and subsequent reductions in chronic diseases.     

价值工程理论在沥青混合料碳排放减排措施中的应用

沥青混合料碳排放减排措施是降低碳排放的有效手段,而对减排措施的选择将直接影响工程的质量和经济效益。本文运用价值工程理论的基本原理与方法,论述价值工程在减排措施选择中的应用方法和步骤,并结合工程实例,对减排措施方案的选择进行研究。结果表明,运用价值工程理论的方法可以择优确定沥青混合料碳排放减排措施。     

Estimating emissions reductions from accelerated vehicle retirement programs

Accelerated vehicle retirement programs offer owners of older vehicles incentives to scrap those vehicles earlier than might otherwise occur. Since older vehicles generally pollute more than newer vehicles, public agencies adopt such programs to reduce air pollutant emissions. Current methods of estimating the emissions reduction benefits of the programs are based on several assumptions and limited empirical evidence. This paper uses data from two large-scale programs in California to demonstrate that changing assumptions can significantly alter the assumed benefits of the program. The results show that vehicle retirement programs are likely to reduce emissions, but probably not as much as expected, particularly for nitrogen oxide and carbon monoxide emissions. The differences in estimates stem from several factors: scrapped vehicles are generally driven fewer miles than other vehicles of the same model year; some of the vehicles would have been scrapped without the program or not have lasted as long as expected; emissions for some pollutants may not be as high as predicted; and replacement vehicles are usually older than the fleet average.     

Modelling Externalities using Dynamic Traffic Assignment Models: A Review

Recently, there has been a growing interest in externalities in our society, mainly in the context of climate and air quality, which are of importance when policy decisions are made. For the assessment of externalities in transport, often the output of static traffic assignment models is used in combination with so-called effect models. Due to the rapidly increasing possibilities of using dynamic traffic assignment (DTA) models for large-scale transportation networks and the application of traffic measures, already several models have been developed to assess the externalities using DTA models more precisely. Different research projects have shown that there is a proven relation between the traffic dynamics and externalities, such as emissions of pollutants and traffic safety. This means that the assessment of external effects can be improved by using temporal information about flow, speed and density, which is the output of DTA models. In this paper, the modelling of traffic safety, emissions and noise in conjunction with DTA models is reviewed based on an extensive literature survey. This review shows that there are still gaps in knowledge in assessing traffic safety, much research is available concerning emissions, and although little research has been conducted concerning the assessment of noise using DTA models, the methods available can be used to assess the effects. Most research so far has focused on the use of microscopic models, while mesoscopic or macroscopic models may have a high potential for improving the assessment of these effects for larger networks.     

Traffic control oriented impact on the persistence of urban air pollutants: A causeway bay revelation during emergency period

The continuous traffic flow is always considered to take a great extent responsibility for the air quality deterioration in urban areas. Meanwhile, traffic control is assumed to be one of the most effective ways to mitigate the high concentration situation as this may cut off the emission directly and satisfy the air quality objectives. Unfortunately, the overdevelopment of central business district area in megacities not only complicates the control plan, but also troubles the process of plan assessment. Because of the road blockages caused by the radical behavior during the Hong Kong protest in 2014, it offers an unexpected chance to evaluate the influence of traffic control oriented plan on urban (i.e., Causeway Bay) air pollution. Hence, we here investigated the six air pollutants concentrations that measured in the time series before, during and after the Hong Kong Protest period. The impact of traffic flow restriction on pollutants’ persistence has been quantified both qualitatively and quantitatively in this study. The results showed that the persistence of pollutants was a general property in Causeway Bay which dominated by the traffic flow pattern. The road blockages, considered as one kind of extreme traffic control plan, would strengthen the persistence of most pollutants (except ozone). Moreover, it also indicated that comprehensive consideration and further balance among different pollutants were necessary when try to reduce pollution in urban area by traffic control.     

Simulating the environmental effects of isolated and area-wide traffic calming schemes using traffic simulation and microscopic emission modeling

This study focuses on the development of a microscopic traffic simulation and emission modeling system which aims at quantifying the effects of different types of traffic calming measures on vehicle emissions both at a link-level and at a network-level. It also investigates the effects of isolated traffic-calming measures at a corridor level and area-wide calming schemes, using a scenario analysis. Our study is set in Montreal, Canada where a traffic simulation model for a dense urban neighborhood is extended with capabilities for microscopic emission estimation. The results indicate that on average, isolated calming measures increase carbon dioxide (CO₂), carbon monoxide (CO), and nitrogen oxides (NO_x) emissions by 1.5, 0.3, and 1.5 %, respectively across the entire network. Area-wide schemes result in a percentage increase of 3.8 % for CO₂, 1.2 % for CO, and 2.2 % for NO_x across the entire network. Along specific corridors where traffic calming measures were simulated, increases in emissions of up to 83 % were observed. We also account for the effect of different measures on traffic volumes and observe moderate decreases in areas that have undergone traffic calming. In spite of traffic flow reductions, total emissions do increase.     

Carbon and energy footprints of electric delivery trucks: A hybrid multi-regional input-output life cycle assessment

Due to frequent stop-and-go operation and long idling periods when driving in congested urban areas, the electrification of commercial delivery trucks has become an interesting topic nationwide. In this study, environmental impacts of various alternative delivery trucks including battery electric, diesel, diesel-electric hybrid, and compressed natural gas trucks are analyzed. A novel life cycle assessment method, an environmentally-extended multi-region input-output analysis, is utilized to calculate energy and carbon footprints throughout the supply chain of alternative delivery trucks. The uncertainties due to fuel consumption or other key parameter variations in real life, data ranges are taken into consideration using a Monte Carlo simulation. Furthermore, variations in regional electricity mix greenhouse gas emission are also considered to present a region-specific assessment for each vehicle type. According to the analysis results, although the battery electric delivery trucks have zero tailpipe emission, electric trucks are not expected to have lower environmental impacts compared to other alternatives. On average, the electric trucks have slightly more greenhouse emissions and energy consumption than those of other trucks. The regional analysis also indicates that the percentage of cleaner power sources in the electricity mix plays an important role in the life cycle greenhouse gas emission impacts of electric trucks.     

Low carbon urban transport scenarios for China and India: A comparative assessment

This paper assesses comparable urban transport scenarios for China and India. The assessment methodology uses AIM/End-use model with a detailed characterization of technologies to analyze two scenarios for India and China till the year 2050. The first scenario assumes continuation and enhancement, in both countries, of policies under a typical business-as-usual dynamics, like constructing metros, implementing national fuel economy standards, promoting alternate fuel vehicles and implementing national air quality standards. The alternative, low carbon scenario assumes application, in both countries, of globally envisaged measures like fuel economy standards as well as imposition of carbon price derived from a global integrated assessment modeling exercise aiming to achieve global 2 °C temperature stabilization target. The modeling results for both countries show that decarbonizing transport sector shall need a wide array of measures including fuel economy, low carbon fuel mix including low carbon electricity supply. The comparison of China and India results provides important insights and lessons from their similarities and differences in the choice of urban transport options. India can benefit from China’s experiences as it lags China in urbanization and income. Modeling assessments show that both nations can contribute to, as well as benefit by aligning their transport plans with global climate stabilization regime.