Intelligent evaluation method for expressway guide signs based on digital coding

To improve the precision and digitalization of expressway infrastructure management and maintenance, this study established a digital coding system and an intelligent evaluation method for expressway guide signs. The coding system comprises classification and location codes to ensure unique identification and spatial positioning of traffic signs within complex expressway networks. Based on current traffic sign standards, a quantitative evaluation framework was established to identify missing, redundant, and improperly positioned expressway guide signs. The proposed method was applied to the Meixian-Epanggong section of the G30 Lianhuo Expressway, which was divided into 13 sections for analysis. The results showed that the digital coding-based evaluation method effectively identified deficiencies in expressway guide sign configuration and spatial placement. These deficiencies included missing signs, insufficient spacing, and excessive offsets of advance exit signs and exit direction signs. In particular, adjacent sign spacing fell below 60 m in two sections, several sections lacked 2 km advance exit signs, and nine sections exhibited substantial positional deviations. In some two-lane exit sections, benchmark points had not been updated according to the current Chinese national standard Road Traffic Signs and Markings (GB 5768-2022). As a result, the installed locations of advance exit signs and exit direction signs deviated substantially from the standard requirements. The findings provide technical support for digital management, maintenance, and adaptive evaluation of expressway guide signs and offer practical value for the digital transformation of expressway infrastructure.