Multilinear Events Sequencing MES incorporates timelines into sequential diagrams, providing a scale that parallels the sequences of events to show the time relationships between events and the incident. The method distinguishes between actors, actions and events.

Definitions Conditions differ from events insofar as they: An event is one actor performing one action Primary Events are directly tied to the accident sequence Secondary Events are events that play a role in the accident but are not directly part of the accident sequence Secondary Events are tied to the Accident Sequence of Events with vertical lines Conditions differ from events insofar as they: (a) describe states or circumstances rather than happenings or occurrences and (b) are passive rather than active

Cause Mapping Cause Mapping utilizes the fundamental principles of systems thinking to identify the basic cause and effect relationships of any problem. Cause Mapping is a 3-step problem solving process for defining, analyzing and solving any type of problem. The steps in Cause Mapping are: Step 1: Problem: Outline the problem by asking who, what, when, and where? Step 2: Analyze: Develop the Cause Map beginning with the unwanted outcome. Working to the right, identify the preceding cause(s) Step 3: Solutions: Identify the best possible solutions.

Multilinear Events Sequencing (MES) Designed to detect hazards arising from the time relationship of various organizational activities.

MES-diagrams A MES-diagram portrays the accident being investigated as a sequence of causally connected events, which represent activities.

Event Blocks Each event block contains the following information about its event description of the action; Actor: the object or person that performed the action Time of event

Causation Event blocks are connected via arrows that represent causation. If event X was necessary for event Y to occur, then MES-diagram contains an arrow from X to Y

MES Diagrams MES-diagrams have two axes The horizontal axis represent time The vertical axis lists actors involved in the accident Event blocks are placed on the diagram according to their time and actor Any relevant information that does not fit event block structure can be placed on MES-diagram as a condition A condition is an oval with some text inside A condition is linked to an event block via an arrow

MES Diagram

MES-diagram Process Events are identified Causal connections between events are identified

Counterfactual reasoning Counterfactual reasoning is a way to establish causal dependency between events We may define a cause to be an object followed by another, and where all the objects, similar to the rest, are followed by objects similar to the second. Or, in other words, where, if the first object had not been, the second never had existed.

Acid Test of MES To determine if the MES charting is correct, the investigator must determine: Given the actors, events, actions, and sequencing, will the scenario developed result in the same outcome? If the answer is yes, then the MES is complete If the answer is no, then there are gaps in the MES

Using MES for Accident Investigations Examine each arrow (causal links between events) Develop countermeasures at each causal link

Activity 5 Perform a literature search and identify one accident scenario or use a work accident you are familiar with. Remove all descriptors (ie: company name, employee names, etc) Using the scenario, apply the Multilinear Events Sequencing technique to develop a causal map of the accident. Complete the assignment and upload the activity to your instructor through D2L by the due date in the course syllabus.