| LOS | Travel Speed Threshold by Base Free-Flow Speed (mi/h) | Volume-to-Capacity Ratio | ||||||
| 55 | 50 | 45 | 40 | 35 | 30 | 25 | ||
| A | >44 | >40 | >36 | >32 | >28 | >24 | >20 | ≤1.0 |
| B | >37 | >34 | >30 | >27 | >23 | >20 | >17 | |
| C | >28 | >25 | >23 | >20 | >18 | >15 | >13 | |
| D | >22 | >20 | >18 | >16 | >14 | >12 | >10 | |
| E | >17 | >15 | >14 | >12 | >11 | >9 | >8 | |
| F | ≤17 | ≤15 | ≤14 | ≤12 | ≤11 | ≤9 | ≤8 | |
| F | Any | >1.0 | ||||||