11.4.1 Life cycle of ESUs
Formerly, Streets were versioned when a change was made to Street Data. Now this is replaced by the creation of a new instance of Street. A new instance is identified by updating the last update date Field.
11.4.2
Some events that mean a change is made to an existing ESU are:
- Re-alignment of a start or end coordinate.
- Alteration of an ESU coordinate (turn point node), if the start and end points remain the same.
- Split of an ESU.
- Permanent closure of an existing ESU.
- Merge of two or more ESUs.
11.4.3
New ESUs must be cross-referenced to the corresponding Street. Some events that mean a new ESU is created are:
- Development or highway structure change.
- Splitting of an ESU.
- Merging of ESUs.
11.4.4
If a section of Highway no longer exists in the real world then the ESU Record must be closed. An ESU Record must not be deleted from the LSG unless created in error. See Table 12 for versioning of ESUs.
Change type and versioning of ESUs:
Creation of a new ESU
New ESU
Re-alignment of a start or end coordinate
ESU instance
Alteration of an ESU coordinate (turn point)
ESU instance
Splitting of an ESU
More than one new ESU
Permanent closure of an existing ESU
ESU instance
Merging of two or more ESUs.
New ESU
Table 12 - Versioning of ESUs