Recent Validation Efforts for a Comprehensive Modal Emissions Model

Abstract

Mobile source emissions estimation techniques play a critical role for regional planning and development of emission control strategies. The primary models for mobile source emissions estimation have been the U.S. Environmental Protection Agency’s MOBILE model and the California Air Resources Board’s EMFAC model. These models work well for large regional areas but are not as well suited for “microscale” evaluation. Over the last several years, the College of Engineering–Center for Environmental Research and Technology (CE-CERT) has been evaluating in-use, light-duty vehicles as part of NCHRP Project 25-11, resulting in the development of a Comprehensive Modal Emissions Model (CMEM). An essential part of any model development process is validating the model. Various validation techniques have been applied to CMEM. This paper describes some of the latest validation work carried out in comparing CMEM results to independent emission testing results (independent in both vehicles and driving cycles). Further, CMEM has been compared with the latest versions of EMFAC and MOBILE. In general, compared with the independent emission measurements, CMEM predicts well. It has been found that CMEM is consistent with MOBILE and EMFAC at low to medium speeds. Greater deviations were found at very low speeds and very high speeds. At high speeds, CMEM tends to predict higher hydrocarbon (HC) emissions and lower oxides of nitrogen (NOx) emissions. At the very low speeds, CMEM tends to predict lower than EMFAC and MOBILE for all emissions. These comparisons are part of an ongoing validation process for development of CMEM.

An integrated modelling approach to estimate urban traffic emissions

“…1) Traffic microsimulation model, Quadstone PARAMICS (Quadstone Paramics, 2008) 2) Microscopic emissions model, Comprehensive Modal Emissions Model (CMEM) (Barth, et al, 1999) (Barth, et al, 2001) 3) Dispersion model: a. AERMOD, Environmental Protection Agency (EPA) regulatory model for near field dispersion (Cimorelli, et al, 2004) b. Quick Urban and Industrial Complex (QUIC), Atmospheric Dispersion Modelling System (Los Alamos National Laboratory, 2010) The morning peak period between 7:00 -9:00 AM is analysed for the following selected weekdays in 2011: 1) June 3, 13, 21, 28, 30 -CO analysis 2) July 7, 12, 13, 18, 27 -NO x analysis CO and NO x are only analysed for June and July respectively, due to limited observed data availability from the concentration measuring sensor.…”

“…Both these parameters are indicative of the driver behaviour and can vary temporally and geographically. Newer emission models such as Comprehensive Modal Emission Model (CMEM) (Barth, et al, 1999) (Barth, et al, 2001), VT Micro (Rakha, et al, 2004), and Motor Vehicle Simulator Microscopic emission models can truly exploit the benefit of using a traffic microsimulation model in order to estimate a more accurate emission rate on roadway links. Evidently, average speed models are rejected for analysis of emissions in this study.…”

“…CMEM was Further details on the model can be obtained from Barth, et al (1999), Barth, et al (2001) and Scora & Barth (2006).…”

Markov Chain Based Emissions Models: A Precursor for Green Control

“…A more realistic model is for instance the comprehensive modal emissions model (CMEM) described in reference (Barth et al 2000). According to this model, second-by-second exhaust emissions and fuel consumption are predicted, for a wide range of vehicle categories and ages.…”

Measurement of Emissions from Passenger-Picking-up Vehicles at Airport Terminals

“…One of such models being widely used is the Comprehensive Modal Emission Model (CMEM) [16]. The CMEM can be used to perform a microscopic level emission analysis for a specific area, such as the airport [13].…”