The Coverage Matrix view is used for keeping track of and managing the relationships between two difference structures. In the case of hazard identification, it enables you to map function item details with guidewords to identify a hazard which arises from the potential of some unexpected or undesirable event. This article describes how to work in the Coverage Matrix view to create and work with hazards and non-hazards. A separate article covers its use in identifying hazardous events.
- SWExtension.HazardIdentification.dll extension is included in your SystemWeaver client installation
- The Hazard extension view is configured (this is done by a system Architect)
- A Hazard identification item in the context of a Hazard analysis area. The view activates on Hazard identification items in this context
- A "master list" exists for the Hazard identification item. This includes:
- A Safety item definition item including at least one Activity (a function that the item performs), an output, a requirement or an assumption
Example Initial Hazard Master List
The Hazard identification model supports both local Guideword containers, i.e., applicable to a specific HARA analysis area and Global Guideword containers, i.e., those that can be applicable across multiple HARA analysis areas. Only guidewords within the current context in a Guideword container can be added for hazard identification.
Getting Acquainted with the View
The view is accessible via either an Items ribbon menu option or the View drop-down.
The view itself is divided into two sections. The top section, called Mappings, is where you will typically start your review of function item details combined with guidewords and identify whether a hazard exists or if there is no hazard, i.e., a non-hazard. Hazard and non-hazard (N/A) items are the two types of "mapping items" created in this view.
The bottom section, called Details, is also a matrix where you can perform all of the same functions that are done above, but it displays each function item and its hazards in list form. It also displays all configured hazard attributes, e.g., the Annotation.
You can filter the list to view the details of only one safety item, by selecting the item in the Mappings section.
Creating a New Hazard
When loaded, both matrices will display the current guidewords and function item details included in the analysis structure. To start, select the Hazard identification item in the structure and load the view. In either matrix, right-click in the cell for a specific combination of function item detail and guideword to create a hazard or non-hazard item. If no hazard is identified, select N/A. If a new hazard is to be created, select Create Hazard.. to create the mapping.
Creating a Hazard in Mappings Section
Creating a Hazard in Details Section
In the Edit Hazard dialog, a Name for the new hazard will be suggested for you, which you can change, and an optional rationale in Annotation can be entered. Annotations can be entered at a later time as well. Click OK to create the new hazard.
Each time you create a new hazard, or new non-hazard, i.e., a N/A item, the new item will display both in the view and in the structure tree under the Hazard identification.
You can create more than one hazard item for a particular combination of function detail and guideword, if applicable. In the below example, there are two hazards associated with "Set speed" and "Too much".
Adding an Existing Hazard
If a hazard is identified as being associated with multiple functions and guidewords composites, it can be applied multiple times. To reuse an existing hazard, right-click in the cell in either matrix and select Add existing Hazard....
A Select dialog will provide a list of all existing hazards for the selected safety function item, i.e., in the row. Find and select the one for reuse (a Search tool is available) and click OK.
You can also Copy and Paste hazards to reuse on the same row.
Editing a Hazard
To edit the name or rationale of an existing hazard, right-click on the cell and select Edit Hazard....
Make your changes in the dialog and click OK to save.
Deleting a Hazard
To delete a hazard, right-click on it in either the Mappings or Details matrix and select Delete Hazard. Multi-select is supported as well.
The selected hazard item is removed for the selected safety item/guideword combination,, but not removed from the server. To delete it from the server, see Deleting Items and Parts.
At the bottom of the Mappings section, there are filter options to make working in the view more efficient.
Checking Not mapped will display only those item details where there are still mapping items missing. Any item details that have all hazards/non-hazards identified will be hidden from view when the option is enabled. In the below example, there is still hazard identification work to be done for "Set speed".
Checking Version mismatch will display in yellow only those mapping items, i.e., hazards/non-hazards , where there is a mismatch between version of the safety item detail or guide word in the mapping item and the actual structure (master lists).
Fixing a Version Mismatch
To obtain more information about the mismatch, select one of the mismatched mapping items. Information will display in Error type.
In the above example, "Too little of Cruise Control Controller" hazard is linked to version 1 of the item detail "Cruise Control Controller" while a newer version (2) is now in the analysis structure in use. To fix the mismatch by updating the version from 1 to 2, right-click on the hazard, click Fix version and select the version update option there. Multi-select is not supported.
To clear either filter option, uncheck the box(es) or click Clear selection.
Mapping Item Status
The view offers very useful visual support in the form of background colors for the hazards/non-hazards so you can easily see the status of each. The status colors are used in both matrices. All are informational and only one is considered an error requiring a need to take action.
- If the background is white, the corresponding items are mapped.
- If the cell is empty with a white background, the corresponding items are NOT mapped.
- If the background color is gray, the corresponding items are mapped to a not-applicable (N/A) mapping item.
- If the background color is dark gray, the mapping is incomplete, i.e., one or more of the needed item(s) to complete the mapping is missing.
- If the background is yellow, one or more of the corresponding item(s) has another version than that in the actual structure (master list).
- If the background is orange, the same combination of items has been mapped into a mapping item (applicable mapping) and not-applicable item, which is contradictory. This must be corrected.
- If the background is red, one or more of the corresponding items comes from outside the actual structure (master list).
Handling Faulty Mappings
At some point during safety work, analysis areas may change and, as a result of this, faulty mappings may appear. For example, a safety item may be removed from the scope of the analysis after mappings between item details and guidewords have already been made. When you select a hazard identification structure, any problem mappings will display in the Faulty mappings section.
To find out more about a faulty mapping, select it in the mappings. Information will display in the Error type section.
In the above example, "Gap control" safety item has been removed from the safety item definition, but a mapping to it still exists. If it is no longer part of the analysis work, then the non-hazard (N/A) item can be removed to resolve the faulty mapping. To do this, right-click and unselect N/A.
Find out how the Coverage Matrix view can be used to identify hazardous events.