Development Of High-Resolution Road Vehicle Emission Inventory For Nanjing Based On Intelligent Transportation Big Data

The rapid economic growth and urbanization process across many countries have created a surge of vehicle population.As a result,traffic congestion,air pollution and energy security concerns have come out as the environmental and social challenges associated with the motorization trend.It is noted that various intelligent transportation system（ITS）technologies have been greatly improved and deployed in recent years,which are capable of providing real-time,high-accuracy,and massive traffic data.These advantages of ITS facilities are essential helpful to establish high-resolution traffic emission inventory and emission management system.Therefore,it is of great significance to develop a data-driven vehicle emission management system based on ITS-informed traffic big data.Nanjing,one of the key cities in terms of vehicle emission controls in the Yangtze River Delta region,is a pioneer city to have deployed ITS technologies in China.This study collected high-volume ITS-informed data in Nanjing during 2013,including 2.4billion radio frequency identification（RFID）detection data,2.5 million traffic video data,150 million floating car data,30 thousand inter-city highway monitoring data and 27thousand real-world fuel consumption records via the Xiaoxiongyouhao application.Transportation simulations,manual investigations and regional statistical analysis have been combined together to model the high-resolution traffic profiles in Nanjing,which estimate link-level and hourly-based traffic parameter for the entire road networking in Nanjing.The ITS-informed traffic data are also applied to localize important parameters of the emission factor model（EMBEV_Nanjing v1.0）,which can estimate the average emission factors of air pollutants and CO₂ from all local fleet categories.With traffic and emission models developed and hybrided,the study established a road emission inventory with high resolution for Nanjing,which can effectively characterize the temporal and spatial patterns as well as emission contributions of each fleet category,and further be applied to quantify emission mitigation benefits under various control scenarios.This study indicates that total emissions of CO,THC,NO_X,PM_2.5,BC,and CO₂from on-road vehicles in 2013,Nanjing are estimated 74 kt,9.4 kt,32 kt,1.1 kt,0.6 kt and 7.4 Mt respectively.Although the central area of Nanjing only accounts for 4%of total area of the whole city,it is estimated responsible for 32%of vehicle activity and31%-38%of vehicle emissions of various pollutants in the entire municipality of Nanjing.High-emission vehicles should be greatly concerned for vehicle emission control.For example,the yellow-label cars meet with pre-China 1 standards contribute only 1.9%of total traffic activity of the light-duty passenger vehicle（LDPV）fleet,but they could account for 18%of the total THC emissions from the LDPV fleet.This study also reveals the significant role of real traffic dynamics in affecting road emission patterns.The total traffic activity in the whole road network would reduce by 10%during weekends compare with that during weekdays,accompanied by an increase of 5%for the average speed;as a result,total vehicle emissions would be lowered by 15%-20%during weekends than those emitted in weekdays.Furthermore,this study assessed emission reduction benefits from major control policies.The results indicate that the most stringent control package,which contains stricter emission standards,promotion of alternative fuel technologies,traffic restrictive policies and aggressive scrappage of older vehicles,could reduce vehicle emissions by 40%-60%for various pollutants.This study provides a vivid case study regarding the application of ITS technologies in environmental management,and will be an important reference for improving technique capability of controlling vehicle emissions...