# Estimation of Driving Direction of Traffic Accident Vehicles for Improving Traffic Safety
## 2 Analysis of Traffic Accident Data from KNPA  
In collecting traffic accident data, the KNPA relies on traffic investigators who collect information related to the accident, such as the coordinates of the accident location, photographs, and a general summary. Given that traffic accidents are typically the result of a complex set of factors, the investigation process records data related to the environmental, temporal, vehicle, and human-related factors (Table 1).  
First, environmental factors that may affect traffic accidents include road-related factors such as the absence of road markings, faulty signs or traffic lights, slippery road surfaces, and poor lighting. The conditions of the road, such as its width, length, slope, and position of intersections, can also influence the likelihood of an accident [17; 18; 19; 20; 21]. Weather conditions such as rain, snow, fog, wind, and dust can reduce driver visibility and make vehicle control difficult, ultimately increasing the risk of accidents [17; 19; 21]. Additionally, animals on the road, particularly at night, can create unpredictable situations for drivers and increase the risk of accidents. The KNPA records information related to environmental factors such as road surface conditions (paved-dry, paved-wet/moist), weather conditions (clear, rainy, cloudy), and others.  
Second, when traffic volume is high during rush hour, the risk of accidents increases [22; 23]. Moreover, drivers commuting during sunrise or sunset are vulnerable to accidents. Sunlight is very intense and can directly shine in drivers' eyes, reducing their visibility and increasing the likelihood of accidents. Additionally, nighttime driving reduces visibility, making it difficult for drivers to detect sudden obstacles, pedestrians, or other vehicles. Furthermore, drivers tend to be less focused and more stressed at night, which can lead to fatigue and impaired concentration, ultimately leading to an increased risk of accidents [24]. The KNPA records information related to time factors, such as the date, time, day of the week, and whether the accident occurred during the day or at night.  
Thirdly, the size and type of vehicles involved in accidents are also related to accident risk [25]. Collisions between large and small vehicles often result in more significant damage to the smaller vehicle. Additionally, technical failures such as faulty brakes, steering systems, tires, lights, seat belts, and other vehicle-related issues can lead to accidents. The KNPA records information related to the types of vehicles involved in accidents, including construction equipment, pedestrians, passenger cars, buses, bicycles, motorcycles, and others.  
Finally, human factors related to the driver include physical, cognitive, and psychological factors. Physical factors include the driver's health status, sleep deprivation, physical discomfort, and illness [26]. Cognitive factors include the driver's attention, concentration, experience, and judgment. Psychological factors include stress, anxiety, depression, anger, etc. These factors interact in complex ways, ultimately increasing the risk of accidents. The KNPA records information related to human factors, including attention status, environmental factors, psychological factors, driving behavior, vehicle operation errors, and mental and physical health status.