| Value | Category | 
|---|---|
| 1 | Not frequent enough | 
| 2 | Stops are far away | 
| 3 | No night service | 
| 4 | Vehicles carriages are in bad condition | 
| 5 | No schedule or schedule is not followed | 
| 6 | Fares are too expensive | 
| 7 | Too crowded | 
| 8 | Too slow | 
| 9 | Other | 
| 10 | No problem | 
| 99 | Missing | 
| Sysmiss |