Comparing Factors Affecting Road Accident Severity Of New Energy Vehicles & Internal Combustion Engine Vehicles Based On Ensemble Learning

In recent years,new energy vehicles(NEVs)feature with energy-saving and environmentfriendly have widely appeared in various life scenes,which coincide with the existing prevalent "green transportation" development concept.However,compared with internal combustion engine vehicles(ICEVs),NEVs mainly use electricity as an energy source and use electric motors to output power,so these vehicles have lower noise and faster acceleration,which are likely to increase the safety risks of pedestrians,cyclists or other road users,especially at low speed driving condition.Therefore,the traffic safety issue of NEVs has aroused public concern,and it is necessary to conduct traffic safety-related research on NEVs.This paper takes NEVs accidents as the main body,combined with ICEVs accidents for comparative research.First,based on the British road safety data,descriptive statistics on NEVs and ICEVs accident data from 3 perspectives of accident circumstances,vehicles and casualties.After that,we focused on hypothesis testing of pedestrian accidents and bicycle accidents involving NEVs or ICEVs,and it was found that whether it was pedestrian accidents or bicycle accidents,the incidence of accidents that NEVs involved was significantly higher than ICEVs,which were 1.20 and 1.21 times of ICEVs,respectively.At the same time,when a vehicle is in slow maneuver(waiting to go-held up,turning right,etc.),the incidence of pedestrian or bicycle accidents involving NEVs is significantly higher than ICEVs.In order to fully understand the reasons for the differences between the two vehicles,3 ensemble learning algorithms like XGBoost,Light GBM and Cat Boost were subsequently used to build accident severity prediction models for the 3 types of accidents(all accidents,pedestrian involved accidents,and bicycle involved accidents)of NEVs and ICEVs.And considering the imbalance of the severity of accidents(few fatal and serious injuries accidents,and a lot of accidents with light injuries),3 sampling methods,SMOTE,ENN,SMOTEENN,and 1 cost-sensitive learning method are used to deal with the imbalance of data categories.Then,the model selection is carried out using the evaluation criteria with G-mean as the main and AUC and accuracy as the auxiliary.Finally,based on the Tree SHAP interpretation method,the mechanism between the severity of NEVs accidents and ICEVs accidents and their influencing factors is revealed.Through the interpretation of models,we found that although the mechanism between the severity of NEVs accidents and ICEVs accidents and their influencing factors are generally consistent,the importance of the factors affecting the severity of accidents of the two types of vehicles are different.NEVs and ICEVs mostly occur in urban areas,but the severity of accidents is low.Although the number of accidents in small towns or rural area is small,they are often more serious,and accidents that occur at midnight or early morning are generally more serious.In addition,vehicles that are older and are in higher-speed maneuver(overtaking,changing lanes,etc.)or vehicles that leaving carriageway(offside and rebounded,offside on to central reservation and rebounded),or overturned,are more serious.Moreover,vehicles controlled by male drivers or drivers with better economic conditions are more likely to have serious traffic accidents.And while those containing elderly people or people who use fewer protective vehicles and pedestrians are also prone to serious traffic accidents.In pedestrian and bicycle accidents,it is also found that while sidewalk is under maintenance,serious traffic accidents are prone to occur in the surrounding area.Meanwhile,road sections without lighting at night are likely to cause serious traffic accidents in pedestrian accidents,and when pedestrians have improper crossing behavior,serious injuries and deaths are also likely to occur.Unexpectedly,in pedestrian accidents that NEVs involved,newer vehicles are more likely to have serious traffic accidents,which differ significantly from other types of accidents.The above-mentioned research expands the accident data of NEVs,increases the number of accident factors,and considers the impact of the interaction of accident factors on the severity of the accident,enriching the existing research.In addition,this paper reveals the mechanism between the severity of NEVs accidents and its influencing factors,provides a scientific basis for relevant departments to formulate management policies for NEVs,and helps to better guarantees the travel safety of new energy vehicles as well as other road users.