| Junctions and other features | Running Lines | Stations, Signal Boxes and Junctions | Distance from Signal Box above | Loops and Refuge Sidings | Notes | |
|---|---|---|---|---|---|---|
| Maximum permissible speed 30 m.p.h. | ||||||
| 1 |
 |
↕ | Harpenden Central Junction | - | ||
| Redbourn | 2m 1239yds | |||||
| --- | ↕ | Hemel Hempstead Station | 6m 353yds | |||