Research Article
Theoretical Research on Longitudinal Profile Design of Superhighways
Table 2
Adjusted classification of highways after peer review.
| Grade | Superhighway | Ordinary highway | Grade III | Grade II | Grade I |
| Design speed/km/h | 180 | 160 | 140 | 160 | 140 | 120 | 140 | 120 | 100 | 120 | 100 | 80 |
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