The setting location of the limit warning signs is a significant factor that affecting their effectiveness. This paper analyzes the main features of accident vehicles and height limiters through ANOVA according to the data of vehicle crash limit overhead accidents. Based on the driver's visual recognition characteristics, combined with the actual situation and laws and regulations set by Chinese relevant road signings, the effectiveness of the hanging height limit sign in the driver's visual recognition process is analyzed. On the basis of considering the safety, using the driver's visual recognition process of the roadside sign, the safety pre-distance model of the front limit sign is proposed and verified by an example. The result shows:(i) When the height difference between the accident vehicle and the height limit is between 0 and 0.6 m, the accident is most likely to occur.(ii) Hanging height limit warning signs can’t meet the demand for large cars safe driving.(iii) The proposed model can help determine the safe setting position of the roadside limit sign and improve the effectiveness of the limit sign. Key words: Height limit sign ；Traffic safety； ANOVA ； Driver characteristic; setting location

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