The TRANSIMS approach to emissions estimation
Transportation systems play a significant role in urban air quality, energy consumption and carbon-dioxide emissions. Recently, it has been found that current systems for estimating emissions of pollutants from transportation devices lead to significant inaccuracies. Most of the existing emission modules use very aggregate representations of traveler behavior and attempt to estimate emissions on typical driving cycles. However, recent data suggests that typical driving cycles produce relatively low emissions with most emissions coming from off-cycle driving, cold-starts, malfunctioning vehicles, and evaporative emissions. TRANSIMS is a simulation system for the analysis of transportation options in metropolitan areas. It's major functional components are: a population disaggregation module; a travel planning module; a regional microsimulation module; and an environmental module. In addition to the major functional components, it includes a strong underpining of simulation science and an analyst's tool box. The purpose of the environmental module is to translate traveler behavior into consequent air quality. The environmental module uses information from the TRANSIMS planner and the microsimulation and it supports the analyst's toolbox. The TRANSIMS system holds the promise of a more complete description of the role of heterogeneity in transportation in emission estimation. The TRANSIMS micro-simulation produces second-by-second vehicle positions defined by 7.5 meter cell locations. A continuous fit is used to produce fine-grained velocities for each 30 meter segment of a link. The distribution of accelerations for each speed bin is estimated based on the standard deviation of speeds in the segment or the gradient of the average cube of the velocity. The model is calibrated with the use of measured speeds and accelerations for a uncongested freeway, a moderately congested freeway and a fast arterial.
- Research Organization:
- Los Alamos National Lab., NM (US)
- Sponsoring Organization:
- US Department of Transportation; Environmental Protection Agency
- OSTI ID:
- 20002138
- Report Number(s):
- CONF-990608-; TRN: IM200002%%138
- Resource Relation:
- Conference: Air and Waste 92nd Annual Meeting and Exhibition, St. Louis, MO (US), 06/20/1999--06/24/1999; Other Information: 1 CD-ROM. Operating Systems: Windows 3.1, '95, '98 and NT; Macintosh; and UNIX; PBD: 1999; Related Information: In: Air and Waste 92nd annual meeting and exhibition proceedings, [9500] pages.
- Country of Publication:
- United States
- Language:
- English
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