Expressways are high-grade roads. The Ministry of Communications of the People's Republic of China "Technical Standards for Highway Engineering" stipulates that expressways refer to "highways that can accommodate an average annual day and night passenger car traffic of more than 25,000 vehicles, are dedicated to separate high-speed vehicles, and have full access control". Although different countries have different names for highways, they all refer to highways with more than 4 lanes (including), two-way separated driving, complete control of entrances and exits, and all use of interchanges.