Emissions

Understanding the environmental impacts of roadway management strategies is essential not only to the estimation of construction cost, but also the protection of the environment and the conservation of the global ecological system. Vehicle speed and fuel consumptions may vary with driving conditions. Vehicle emissions can be estimated based on the speed, acceleration rate, and Vehicle Specific Power (VSP), which could normally be listed in an Operating Mode Identification (OMID) table. The relationships between pavement roughness (indicated by International Roughness Index or IRI) and speed/fuel consumption could be reflected by linear models, while the IRI is nonlinearly correlated to the emissions. It is recommended further identifying the relationships between IRI and emissions with more on-road tests for all types of vehicles on different types of roadway systems, so as to minimize the environmental, ecological, and even public health impacts through proper roadway management strategies.

MIRAVEC Report D2.1.  This is a report of the findings in Work Package 2 (WP2) in MIRAVEC. The objective of this WP is to describe existing modelling tools and evaluate their capabilities with respect to analysing the effects identified in WP1 “Road infrastructure influence effects on vehicle energy consumption and associated parameters”. The variables identified in WP1 and considered to be the most important to take into consideration when estimating the impact of road infrastructure on road traffic energy use are texture (MPD), IRI (unevenness), rut depth (RUT), gradient (RF), crossfall, horizontal curvature (ADC), road width, traffic volume (AADT) and speed (v). In this report, a selection of projects that have evaluated road characteristics and the effect on energy use are described and analysed. The results of these project shows that there can be benefits energy wise in taking the energy aspect into consideration when planning a new road or choosing rehabilitation measure of the pavement. 

MIRAVEC Report D5.3.  The objective of MIRAVEC was to build on existing knowledge and models in order to achieve a more holistic view considering a broad variety of effects. The project results are compiled in this final report of MIRAVEC project. The first part of this final report is a short summary on the findings and outputs of all Work Packages (WP), while the second part is a summary of all recommendations to National Road Administrations (NRAs) on how to implement the findings, models and tools in pavement and asset management systems. The main findings and recommendations of the project can be summarised as follows:  Five major groups of parameters influencing road vehicle energy and fuel consumption were identified, of which a subset was selected based on impact, potential for influence by National Roads Administrations and integration into existing fuel consumption models. Further analysis showed that while currently monitored parameters can be used for modelling several effects of the infrastructure influence, knowledge gaps remain with respect to other parameters and the correct modelling of associated effects.  There is no current model which takes all infrastructure-related effects into account. Most models for fuel consumption and CO2 emission of road vehicles focus on vehicle and traffic flow characteristics and tend to neglect details of the infrastructure. The Swedish VETO model is one of the most advanced models in this respect and was the basis of many analyses. As the knowledge about the infrastructure influence increases, these models offer the possibility to integrate this knowledge into decision making.  The spreadsheet tool developed in WP3 allows the comparison of the effects of different infrastructure-related measures on fuel consumption and CO2 emission. It requires data about the most widely available pavement and road layout parameters and uses information about traffic flow and vehicles as background information. While the tool can be applied even with limited data, the strong influence of these background data found in the analysis may supersede the infrastructure effects in some cases.  The investigation of the current situation with regard to the occurrence of this topic in pavement and asset management found a growing awareness of its importance with road managers, but so far very limited implementation in the actual systems. While future models based on the more commonly monitored infrastructure parameters will make the integration of vehicle CO2 emission feasible, acceptance and weight in decision making in the view of limited financial resources for maintenance still remain to be achieved. 

Various reports and presentations from the EU MIRAVEC looking at the impact of infrastructure on vehicle energy.

MIRAVEC Report D1.1: This document describes the different road infrastructure parameters which can contribute to the overall road vehicle energy consumption and highlights those which can be influenced by infrastructure design. It is a report on the effects and parameters that need be considered in order to determine the influence of road infrastructure on road vehicle energy consumption by modelling. The effects and properties were divided into the following five groups: A. Effects of pavement surface characteristics (rolling resistance, texture, longitudinal and transversal unevenness, cracking, rutting, other surface imperfections) B. Effects of road design and layout (e.g. road curvature, gradient and crossfall, lane provision) C. Traffic properties and interaction with the traffic flow (e.g. free flowing traffic vs. stop-and-go, speed limits, access restrictions) D. Vehicle and tyre characteristics including the potential effect of technological changes in this area E. Meteorological effects (e.g. temperature, wind, water, snow, ice)

Detailed reference book on the different types of driving cycles used for modelling emissions.

The current work being undertaken for the Ministry of Transport, focuses on the effects of road transport on aquatic ecosystems and by default is concerned with the contaminants and their loads generated by motor vehicles. All of the stormwater quality models that are commonly in use deal with the overall loads produced by all activities within urban areas. This report focuses on three aspects of the information required by the VFEM-W. These aspects are those that provide the framework for the emissions hub within the model (refer Figure. 1.1). The
cells for any given source within the hub contain three key pieces of information that allow emissions of contaminants to be calculated over time within a given section of roadway. These are:

• The concentration of contaminant present. 
• The rate that the contaminant is released by an individual motor-vehicle.\\\\
• The rate at which the emission from a particular source is deposited to the road surface and is then available for stormwater transport.

A wide range of contaminants are emitted from motor vehicles. Typically estimates of emissions are only required for those contaminants whose discharge to the environment is of environmental significance. The focus of this report is for those key sources known to contribute contaminants and those contaminants identified as being of potential environmental concern (COPC). Typically the COPC include the USEPA priority inorganic and organic pollutants in addition to a range of motor vehicle specific organic compounds. However where data is available on other significant contaminants in emissions from motor vehicles it is identified in this document.

The report presents information on the emissions from motor vehicles in seven sections:

• Section 2 provides an overview of the vehicle fleet and how it is categorised and how VFEM-W handles vehicle types and some of the core factors that influence emissions.
• Section 3 provides information about emissions from brake systems.
• Section 4 presents information about emissions from motor vehicle tyres.
• Section 5 presents information about emissions of lubricants and greases.
• Section 6 provides information about emissions of coolants.
• Section 7 provides information about the emissions from vehicle exhaust systems and includes specific discussion on the emission of contaminants from vehicles with catalytic converters.
• Section 8 examines the wear of material from bitumen road surfaces.

In each of these sections information is presented on the contaminants present in that source and the available information on emission rates for that source. Finally in Section 9 information is presented in relation to the pathway from the source to the road surface, as not all of the emitted contaminant is likely to end up on the road surface and then be available for stormwater transport to a fresh or coastal receiving environment. Factors are identified that provide a first estimate of air to road deposition.

Paper proposing modelling of vehicle emissions. This formed the basis for the model implemented in HDM-4.

Paper proposing modelling of vehicle emissions.

Paper proposing modelling of vehicle emissions.