Moving towards Sustainability: Road Grades and On-Road Emissions of Heavy-Duty Vehicles—A Case Study

Wendan Zhang,Yi Zhang,Jian Lu,Ping Xu

doi:10.3390/su70912644

Abstract

On-road vehicle emissions are one of the major sources of transport emissions. As a key design factor, road grades (or road slopes) have significant effects on on-road vehicle emissions, particularly on Heavy-Duty Vehicles (HDVs). However, the research into the relationship between road grades and on-road vehicle emissions is very rare in China. Taking a road network in Taiyuan, China, as a study area, this paper explored the influences of road grades on carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) emissions of HDVs. Combining emissions data collected by Portable Emission Measurement System (PEMS) with Vehicle Specific Power (VSP), we developed an emission rate model of HDVs. Then, we integrated it with the traffic simulation model VISSIM to attain the emissions of HDVs on nine scenarios differentiated by road grades. The results showed that the three emissions are found to be highly correlated to road grades, among which the CO emissions are most sensitive to the change of road grades and the HC emissions least. Compared to the emissions at 0% grade, the emissions at 4% grade will be boosted from 39.0% to 60.6%. The CO and NOx emissions increase with the road grades in all nine scenarios, while the variations of HC emissions in different scenarios were complicated. The findings of this research will provide insights for policy-makers, scholars, and practitioners into strategies for improving road design to reduce traffic emissions and develop sustainable transportation in China.

Highlights

The combustion of fossil fuels by vehicles leads to road traffic emissions, which are one of the most significant sources of primary air pollutants
With data collected in Taiyuan, China, the aim of this paper is to explore the relationship between road grades and Carbon Monoxide (CO), Hydrocarbons (HC) and Nitrogen Oxides (NOx) emissions of Heavy-Duty Vehicles (HDVs) in, and provide guidance for the design of road grades that facilitates the reduction of on-road vehicle emissions and the development of sustainable transportation
We present research results from a case study aiming at unraveling the influences of road grades on CO, HC and NOx emissions of HDVs, with data collected from Taiyuan Metropolitan

Summary

Introduction

The combustion of fossil fuels by vehicles leads to road traffic emissions, which are one of the most significant sources of primary air pollutants. Significant progress has been made to limit the pollutant emissions from individual vehicles, emissions from conventional gasoline-powered motor vehicles remain a concern in the United States (U.S.) and account for the majority of petroleum consumption [5]. The transport sector is the largest contributor to Nitrogen Oxides (NOx) emissions, accounting for 46% of total European Union (EU)-28 emissions in 2012 [6]. The precise information of on-road vehicle emissions is crucial for the evaluation of the contribution of road traffic in general. For this reason, major efforts are being made for the reduction of polluting emissions from road transport all over the world [7]

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