Table 1. The summary of previous literatures related to accident severity.

Author	Goal			Influencing factors considered									Severity considered	Models
	A	B	C	I	II	III	IV	V	VI	VII	VIII	IX
Sattar et al. [10]			√		√	√		√	√		√	√	severe, non-severe	GNN, RF, XGBoost, ANN
Yan et al. [8]	√	√				√		√	√	√	√	√	non-fatal, fatal	LightGBM
Mohammadpour et al. [28]	√		√		√	√		√	√		√	√	fatal and severe injury, less severe injury, PDO	RF, KNN, GBDT, SVM, Multi-Layer Perceptron
Hyodo et al. [11]	√	√		√		√	√	√	√	√			minor, severe, or fatal	Ordered Probit Model
Hosseinzadeh et al. [6]	√	√	√	√	√	√		√		√			fatal, non-fatal	SVM, random parameter logit model
Li et al. [5]	√	√	√	√		√		√	√	√		√	incapacitating crash, fatal crash	RF, GBDT, AdaBoost, Mixed Logit
Islam et al. [7]	√	√		√		√		√	√	√			fatal, non-fatal crashes	multinomial logit model
Ahmed et al. [18]	√	√	√	√		√		√	√		√	√	fatal, serious, minor, and non-injury	RF, Decision Jungle, AdaBoost, XGBoost, LightGBM, CatBoost
Shiran et al. [13]	√		√	√		√	√	√	√	√			PDO, fatality, severe injury, other visible injuries, and complaint of pain	MNL, ANN-MLP, CHAID, and C5.0
Zainuddin et al. [16]	√					√	√	√			√	√	non-fatal or fatal accident.	Descriptive and chi-square test
Ahmed et al. [18]	√	√	√	√		√		√	√		√	√	fatal, serious, minor, and non-injury crashes	RF, Decision Jungle, AdaBoost, XGBoost, LightGBM, CatBoost
Zhou et al. [29]	√	√	√	√	√	√		√			√		no injury, injury, fatality	MNL, Naive Bayes, SVM, and XGBoost
Panda et al. [30]	√	√	√		√	√		√		√			killed and injured	SVM, RF, GBDT, XGBoost
Yang et al. [22]	√	√				√		√	√				property loss, Injuries, Fatal	XGBoost + Bayesian network model
Mahashhash et al. [24]	√	√			√	√				√	√		non-severe injury, Severe injury or fatal	Binary logit model
Lee et al. [31]	√	√		√	√	√			√		√	√	PDO, bodily damage	Logit Model

A. Identify the key contributing factors; B. Examine the relationships between factors and accident severity; C. Compare several model’s performance.

I. Driver-related and driving behavior factors. II. Vehicle-related factors. III. Road geometry factors. IV. Traffic characteristic factors V. Weather factors. VI. Lighting conditions. VII. Crash characteristic factors. VIII. Temporal variables. IX. Other environment factors, such as built environment, spatial configuration.