Emission estimation based on traffic models and measurements

Emission estimation based on traffic models and measurements
Author: Nikolaos Tsanakas
Publisher: Linköping University Electronic Press
Total Pages: 131
Release: 2019-04-24
Genre:
ISBN: 9176850927

Traffic congestion increases travel times, but also results in higher energy usage and vehicular emissions. To evaluate the impact of traffic emissions on environment and human health, the accurate estimation of their rates and location is required. Traffic emission models can be used for estimating emissions, providing emission factors in grams per vehicle and kilometre. Emission factors are defined for specific traffic situations, and traffic data is necessary in order to determine these traffic situations along a traffic network. The required traffic data, which consists of average speed and flow, can be obtained either from traffic models or sensor measurements. In large urban areas, the collection of cross-sectional data from stationary sensors is a costefficient method of deriving traffic data for emission modelling. However, the traditional approaches of extrapolating this data in time and space may not accurately capture the variations of the traffic variables when congestion is high, affecting the emission estimation. Static transportation planning models, commonly used for the evaluation of infrastructure investments and policy changes, constitute an alternative efficient method of estimating the traffic data. Nevertheless, their static nature may result in an inaccurate estimation of dynamic traffic variables, such as the location of congestion, having a direct impact on emission estimation. Congestion is strongly correlated with increased emission rates, and since emissions have location specific effects, the location of congestion becomes a crucial aspect. Therefore, the derivation of traffic data for emission modelling usually relies on the simplified, traditional approaches. The aim of this thesis is to identify, quantify and finally reduce the potential errors that these traditional approaches introduce in an emission estimation analysis. According to our main findings, traditional approaches may be sufficient for analysing pollutants with global effects such as CO2, or for large-scale emission modelling applications such as emission inventories. However, for more temporally and spatially sensitive applications, such as dispersion and exposure modelling, a more detailed approach is needed. In case of cross-sectional measurements, we suggest and evaluate the use of a more detailed, but computationally more expensive, data extrapolation approach. Additionally, considering the inabilities of static models, we propose and evaluate the post-processing of their results, by applying quasi-dynamic network loading.

Real-time Vehicle Emission Estimation Using Traffic Data

Real-time Vehicle Emission Estimation Using Traffic Data
Author: Anjie Liu
Publisher:
Total Pages: 142
Release: 2019
Genre: Traffic flow
ISBN:

The current state of climate change should be addressed by all sectors that contribute to it. One of the major contributors is the transportation sector, which generates a quarter of greenhouse gas emissions in North America. Most of these transportation related emissions are from road vehicles; as result, how to manage and control traffic or vehicular emissions is therefore becoming a major concern for the governments, the public and the transportation authorities. One of the key requirements to emission management and control is the ability to quantify the magnitude of emissions by traffic of an existing or future network under specific road plans, designs and traffic management schemes. Unfortunately, vehicular traffic emissions are difficult to quantify or predict, which has led a significant number of efforts over the past decades to address this challenge. Three general methods have been proposed in literature. The first method is for determining the traffic emissions of an existing road network with the idea of measuring the tail-pipe emissions of individual vehicles directly. This approach, while most accurate, is costly and difficult to scale as it would require all vehicles being equipped with tail-pipe emission sensors. The second approach is applying ambient pollutant sensors to measure the emissions generated by the traffic near the sensors. This method is only approximate as the vehicle-generated emissions can easily be confounded by other nearby emitters and weather and environmental conditions. Note that both of these methods are measurement-based and can only be used to evaluate the existing conditions (e.g., after a traffic project is implemented), which means that it cannot be used for evaluating alternative transportation projects at the planning stage. The last method is model-based with the idea of developing models that can be used to estimate traffic emissions. The emission models in this method link the amount of emissions being generated by a group of vehicles to their operations details as well as other influencing factors such as weather, fuel and road geometry. This last method is the most scalable, both spatially and temporally, and also most flexible as it can meet the needs of both monitoring (using field data) and prediction. Typically, traffic emissions are modelled on a macroscopic scale based on the distance travelled by vehicles and their average speeds. However, for traffic management applications, a model of higher granularity would be preferred so that impacts of different traffic control schemes can be captured. Furthermore, recent advances in vehicle detection technology has significantly increased the spatiotemporal resolutions of traffic data. For example, video-based vehicle detection can provide more details about vehicle movements and vehicle types than previous methods like inductive loop detection. Using such detection data, the vehicle movements, referred to as trajectories, can be determined on a second-by-second basis. These vehicle trajectories can then be used to estimate the emissions produced by the vehicles. In this research, we have proposed a new approach that can be used to estimate traffic generated emissions in real time using high resolution traffic data. The essential component of the proposed emission estimation method is the process to reconstruct vehicle trajectories based on available data and some assumptions on the expected vehicle motions including cruising, acceleration and deceleration, and car-following. The reconstructed trajectories containing instantaneous speed and acceleration data are then used to estimate emissions using the MOVES emission simulator. Furthermore, a simplified rate-based module was developed to replace the MOVES software for direct emission calculation, leading to significant improvement in the computational efficiency of the proposed method. The proposed method was tested in a simulated environment using the well-known traffic simulator - Vissim. In the Vissim model, the traffic activities, signal timing, and vehicle detection were simulated and both the original vehicle trajectories and detection data recorded. To evaluate the proposed method, two sets of emission estimates are compared: the "ground truth" set of estimates comes from the originally simulated vehicle trajectories, and the set from trajectories reconstructed using the detection data. Results show that the performance of the proposed method depends on many factors, such as traffic volumes, the placement of detectors, and which greenhouse gas is being estimated. Sensitivity analyses were performed to see whether the proposed method is sufficiently sensitive to the impacts of traffic control schemes. The results from the sensitivity analyses indicate that the proposed method can capture impacts of signal timing changes and signal coordination but is insufficiently sensitive to speed limit changes. Further research is recommended to validate the proposed method using field studies. Another recommendation, which falls outside of this area of research, would be to investigate the feasibility of equipping vehicles with devices that can record their instantaneous fuel consumption and location data. With this information, traffic controllers would be better informed for emission estimation than they would be with only detection data.

Transitions Towards Sustainable Mobility

Transitions Towards Sustainable Mobility
Author: Jo A.E.E. van Nunen
Publisher: Springer Science & Business Media
Total Pages: 321
Release: 2011-08-19
Genre: Business & Economics
ISBN: 3642211925

Delivering a sustainable transport system is not just a matter of adopting a number of technological innovations to improve performance in terms of people, planet, and profits. A broader structural and societal transition is needed in technology, as well as in institutions, behavioural patterns, and the economy as a whole. In this broader view, neither the free market nor the public sector will be the unique key player in making this transition happen. Elements of such an approach are presented in this book in a number of domains: integrating transport infrastructure and land use planning, thus connecting fields that are rather unconnected in day-to-day policies; experiments with dynamic transport optimization, including reports on pilot projects to test the viability of transitions; towards reliable transport systems, describing a reversal from supply-driven towards demand-driven approaches; and sustainable logistics and traffic management, from ‘local’ city distribution to global closed supply chain loops.

Traffic Data for Integrated Project-level PM [subscript] 2.5 Conformity Analysis

Traffic Data for Integrated Project-level PM [subscript] 2.5 Conformity Analysis
Author: Heng Wei (Civil engineer)
Publisher:
Total Pages: 76
Release: 2014
Genre: Motor vehicles
ISBN:

As required by the U.S. Environmental Protection Agency (EPA), the MOVES model is the mandatory emission tool for new PM hot-spot analyses for project-level conformity determinations that began after December 20, 2012. Localized traffic data inputs to the model are crucial in maximizing its capability to accurately reflect the PM2.5 emissions associated with transportation programs and projects. However, accurately acquiring local traffic operating related data for project-level MOVES analysis is always a challenge to realistic practices. To address the issue, the three existing traffic data sources in Ohio that can be used as inputs for the MOVES model have been identified and analyzed through the project. The first one is referred to as the ATR data source, which contains hourly or 15-minute traffic volume and vehicle composition. The second one, PVR data source, provides individual vehicle's timestamp, class and speed information. The third one is the micro-simulation data source, which includes individual vehicle's class, speed profile and acceleration profile. The applicability of the available data sources has been evaluated by using the sample data collected on the I-275 freeway in Cincinnati, Ohio. Specifically, the roadside PM2.5 concentration is estimated based on the sample traffic data and the modeled concentration is compared to the observed data. The compared results indicate that the PVR data source is preferred for the project-level PM2.5 analysis. It requires less effort to collect and provides the most accurate results when compared to other data sources. The normalized mean-square-error of the modeled concentration can be reduced by 30.5% if the PVR data are used with the operating mode distribution data prepared based on the simulation data source. Finally, an easy-to-use computer tool in the ArcGIS environment, termed as Traffic Air Environmental Health Impact Analysis (TAEHIA) supporting system, has been developed to facilitate the application of the identified data sources into the PM2.5 conformity analysis conforming to the ODOT and EPA guidelines. The TAEHIA system is designed to: 1) incorporate the traffic data sources available in Ohio; 2) implement the PM2.5 conformity steps as recommended by the EPA hit-spot conformity analysis guideline; and 3) simplify users' tasks in the conformity analysis. The application of the TAEHIA system has been demonstrated in two case studies. As shown by the case studies, it is a user-friendly, straightforward way to analyze the transportation conformity within the TAEHIA environment.

Emissions Reduction Through Better Traffic Management

Emissions Reduction Through Better Traffic Management
Author:
Publisher:
Total Pages: 398
Release: 2001
Genre: Air
ISBN:

The objectives of this study were to: (1) evaluate a new low-cost approach for measuring on-road tailpipe emissions of highway vehicles; (2) investigate factors that affect the amount and variability of on-road emissions, using statistical methods; and (3) devise and demonstrate methods for designing and conducting observational experiments that realistically evaluate pollution prevention strategies for on-road vehicles. Portable instruments were used for measuring carbon monoxide (CO), nitric oxide (NO), and hydrocarbon (HC) emissions and vehicle activity (e.g., vehicle speed, engine parameters) on a second-by-second basis. Data collection, quality assurance, reduction, and analysis protocols were developed. Field data collection occurred in a pilot and an evaluation phase. In total, over 1,200 one-way trips were made with more than 20 vehicles, 4,000 vehicle-miles traveled, 160 hours of data, and 10 drivers. The pilot study was used to identify key factors influencing on-road emissions and as input to the design of the evaluation study. In the evaluation study, data were collected intensively with a small number of vehicles on two corridors before and after signal timing and coordination changes were implemented. For the first corridor, changes in signal timing and coordination did not result in a significant change in traffic flow or emissions. However, substantial reductions in emissions were estimated for uncongested versus congested traffic flow when comparing travel in the same direction at different times of day. For the second corridor, there were significant improvements in traffic flow and some reduction in emissions for three of the four time period and travel direction combinations evaluated. The impact of signal timing and coordination changes with respect to non-priority movements involving cross-streets was evaluated. For the first corridor, there was no statistically significant observed change in emissions for non-priority movements. For the second corridor, there typically was a decrease in average speed and an increase in emissions for non-priority movements; however, many of the observed changes were not statistically significant. The study also demonstrated other analysis methods, including: (a) macro-scale analysis of trip average emissions and traffic parameters; (b) micro-scale analysis of second-by-second emissions and vehicle operation; (c) mesoscale analysis of modal emission rates; and (d) spatial analysis of emissions at specific locations along the corridors. Both statistical and theoretical-based approaches were evaluated. The implications of the study results for pollution prevention strategies are discussed. Conclusions are presented regarding instrumentation, protocols, analysis techniques, and case study-specific findings. Recommendations are given regarding future applications of on-board measurements.

AI-Based Transportation Planning and Operation

AI-Based Transportation Planning and Operation
Author: Keemin Sohn
Publisher: MDPI
Total Pages: 124
Release: 2021-03-29
Genre: Technology & Engineering
ISBN: 3036503641

The purpose of this Special Issue is to create an an academic platform whereby high-quality research papers are published on the applications of innovative AI algorithms to transportation planning and operation. The authors present their original research articles related to the applications of AI or machine-learning techniques to transportation planning and operation. The topics of the articles encompass traffic surveillance, traffic safety, vehicle emission reduction, congestion management, traffic speed forecasting, and ride sharing strategy.

Traffic Data for Integrated Project-Level PM2.5 Conformity Analysis

Traffic Data for Integrated Project-Level PM2.5 Conformity Analysis
Author: Heng Wei (Civil engineer)
Publisher:
Total Pages: 76
Release: 2014
Genre: Automobiles
ISBN:

As required by the U.S. Environmental Protection Agency (EPA), the MOVES model is the mandatory emission tool for new PM hot-spot analysts for project-level conformity determinations that began after December 20, 2012. Localized traffic data inputs to the model are crucial in maximizing its capability to accurately reflect the PM2.5 emissions associated with transportation programs and projects. However, accurately acquiring local traffic operating related data for project-level MOVES analysis is always a challenge to realistic practices. To address the issue, the three existing traffic data sources in Ohio that can be used as inputs for the MOVES model have been identified and analyzed through the project. The first one is referred to as the ATR data source, which contains hourly or 15-minute traffic volume and vehicle composition. The second one, PVR data source, provides individual vehicle's time stamp, class and speed information. The third one is the micro-simulation data source, which includes individual vehicle's class, speed profile and acceleration profile. The applicability of the available data sources has been evaluated by using the sample data collected on the I-275 freeway in Cincinnati, Ohio. Specifically, the roadside PM2.5 concentration is estimated based on the sample traffic data and the modeled concentration is compared to the observed data. The compared results indicate that the Ppr data source is preferred for the project-level PM2.5 analysis. It requires less effort to collect and provides the most accurate results when compared to other data sources. The normalized mean-square-error of the modeled concentration can be reduced by 30.5% if the PVR data are used with the operating mode distribution data prepared based on the simulation data source. Finally, an easy-to-use computer tool in the ArcGIS environment, termed as Traffic Air Environmental Health Impact Analysis (TAEHIA) supporting system, has been developed to facilitate the application of the identified data sources into the PM2.5 conformity analysis conforming to the ODOT and U.S. EPA guidelines. The TAEHIA system is designed to: 1) incorporate the traffic data sources available in Ohio; 2) implement the PM2.5 conformity analysis steps as recommended by the EPA hot-spot conformity analysis guideline; and 3) simplify users' tasks in the conformity analysis. The application of the TAEHIA system has been demonstrated in two case studies. As shown by the case studies, it is a user-friendly, straightforward way to analyze the transportation conformity within the TAEHIA environment.

Veinbook

Veinbook
Author: Sergio Ibarra Espinosa
Publisher: Independently Published
Total Pages: 194
Release: 2018-12-13
Genre:
ISBN: 9781791571153

Road traffic is the most important source of pollutants in urban centers. The characterization of the pollution generated by the vehicles can be cumbersome. VEIN is an R package designed to estimate vehicular emissions with different approaches covering traffic flow processing, selection of emission factors, and estimation and post-processing of emissions into databases and maps. VEIN allows you to know where are the sources of pollution and at what time are emitted. This book also covers the generation of inputs for WRF-Chem model.