How Much Can Vehicle Emissions Be Reduced?: Exploratory Analysis of an Upper Boundary Using an Emissions-Optimized Trip Assignment

Abstract

The development of a trip-assignment model designed to systematically compute emissions-optimized traffic flows for carbon monoxide is explored. Then the exploratory theoretical emissions-optimized tripassignment model is used to estimate the maximum carbon monoxide emissions reductions under varying congestion levels on a hypothetical network. The experimental results indicate moderate reductions in system-level vehicle emissions under emissions-optimized trip assignment compared with the conventional time-dependent user-equilibrium and system-optimized models. They suggest a possible method for approximating an upper boundary of expected emissions reductions using the standard travel-demand model with a modified trip-assignment objective function. The approximate boundary is useful as an estimate of emissions reductions that might be possible under optimal conditions (e.g., drivers choose emissions-optimized routes, fully implemented intelligent transportation systems, etc.). In other words, the upper boundary suggests that current traffic optimization strategies may be insufficient to fully remedy air quality problems created by mobile-source emissions.

Influential vectors in fuel consumption by an urban bus operator: Bus route, driver behavior or vehicle type?

“…Travel time cost and fuel consumption are usually considered in travel cost estimation (Ortuzar and Willumsen, 2001). Research on the relationship between route choice models and energy savings and environmental concerns is scarce (Sugawara and Niemeier, 2002;Ericsson et al, 2006) and there is only information about route length and travel time in traffic guidance systems and no other valuable information concerning emissions.…”

Modeling the effects of congestion on fuel economy for advanced power train vehicles

“…Following previous emissions modeling research (Barth and Boriboonsomsin 2008;Sugawara and Niemeier 2002), an exponentiated fourth-order polynomial functional form is used: …”

Emission-based static traffic assignment models

“…Considering such trend for all ranges of speeds has significant impact on the formulation and solution of E-UE and E-SO because the link cost function may not be monotonically increasing and consequently traffic assignment formulations may not have unique solution. Sugawara and Niemeier [18] developed CO emission-based traffic assignment model and solved using meta-heuristic simulated annealing. Ahn Fig.…”

“…The three types of environmental TA models are as follows: (1) models with environmental objectives, (2) models with environmental constraints, and (3) models for environmental impact assessment [13]. Studies based on environmental objectives include [15,[17][18][19]. The objective can be either only emissions or combinations of emissions and other factors including travel times.…”