Structure of GAD Data
GAD Objects
All GAD data is associated with a Geotechnical Asset, which may be an earthwork (cutting, embankment or bund) or an at-grade extent.
The characteristics and condition of each Asset is structured into a series of inter-related objects to assist with the efficient storing and manipulation of the data.
The GAD objects and the relationships between them are defined in the table below.
Links to a series of diagrams are provided to aide understanding.
| Object name | Description | Figure(s) to refer to |
| Geotechnical Asset | Top level object as defined by CS641, which may be an earthwork (cutting, embankment or bund) or an at-grade extent. Previously referred to in HAGDMS as an earthwork. |
Figure 1, Figure 2 |
| Inventory Item | An object within a Geotechnical Asset that describes a characteristic of the asset. Includes vegetation, drainage, SGMs, extents of hazards and deteriorating slopes (see below), which define the extent on the asset within which an associated condition item could lie. |
Figure 1 |
| Access Constraint | Records a section of a Geotechnical Asset where access for inspection is restricted (a specific type of inventory item). | Figure 1 |
| Inventory Set | A grouping of two or more associated inventory items on the same asset with engineering interdependency. An example would be slope drainage below a sheet pile wall. | |
| Condition Item |
An object within a Geotechnical Asset that describes a characteristic of the Asset that is a measure of deterioration or potential for deterioration of a part of the asset. |
Figure 1 |
| Condition Set | One or more associated Condition Items on the same Asset. Key attributes of the condition set will be the classification and feature grades in accordance with CS641. A set may comprise only one Condition Item so that it may be classified. The Condition Items within a set must be on the same Asset as each other, but may be on different Inventory Items. Classification is optional, to allow related condition items in the same unclassified observation to be migrated as a set. |
Figure 1 |
| Location | Spatially located attribute of all GAD objects (except for activities). Locations of “sets” are derived from their constituent “items”. Location data also includes any linkage to the highway network. | Figure 1, Figure 2 |
| Slope Geometry | A point location within the extents of the Geotechnical Asset describing the slope height, angle and bearing Slope Geometry records at the start and end of an asset are pinned to the Asset extents. Intermediate Geometry records have a location fixed to OS coordinates. |
Figure 2 |
| Non-Routine Maintenance Requirement (NRMR) | Details of infrequent intervention to be undertaken on an object. Includes the type and frequency of maintenance. An example of an NRMR would be annual vegetation clearance. | |
| Activity | A time stamped action undertaken on any GAD object. Includes construction, inspections, approval, archiving etc. |
Diagrams
Figure 1: Principal GAD Objects and the relationship between them (note that the red dots denote locations)
Figure 2: Representation of slope geometry in GAD
