Use Valid Segment Order
When you are adding, inserting, deleting, or editing horizontal alignment segments, there are valid and invalid ways in which segment types can be connected. For instance, a combining spiral must be preceded and followed by an arc; it cannot connect to any other segment type. Some typical, and valid, sequences of segment types include:
- Residential streets: Line > Arc > Line >
- High speed-streets and ramps: Line > Spiral in > Arc > Spiral out > Line
- Unusual high-speed ramps: Line > Spiral in > Arc > Combining spiral > Arc > Spiral out > Line
|
Valid Segment Connections |
|||||||
| From | To | POB | Line | Arc | Spiral in | Spiral out | Combining spiral |
| POB |
— |
OK |
OK |
OK |
OK |
— |
|
| Line |
— |
OK |
OK |
OK |
OK |
— |
|
| Arc |
— |
OK |
OK |
OK |
OK |
OK |
|
| Spiral in |
— |
OK |
OK |
— |
OK |
— |
|
| Spiral out |
— |
OK |
OK |
OK |
— |
— |
|
| Combining spiral |
— |
— |
OK |
— |
— |
— |
|
Note: Tangency is assumed when a line transitions into an arc or a spiral.
