Maintenance activities and inter-firm relationships. Ergonomic analyses in a public transport company

Objectives and analytical framework
Maintenance activities are identified as critical both to operator safety and to systems safety and reliability. As regards operator safety, several studies have emphasized a high level of maintenance-related accidents. Maintenance was thus associated with 15-20% of all accidents in Europe in 2006. As regards systems safety and reliability, several accident investigations have identified maintenance failings as one of the main contributors to unanticipated events in various critical safety domains.
However, studies on maintenance were mainly interested in human errors and individual-level issues. Ergonomic literature on real maintenance activities and practices is rather scarce. The consequences on safety of organizational changes in this field, such as outsourcing of these activities, have received little attention. Thus, this paper presents ergonomic analyses aimed at developing understanding of normal real maintenance activities, while taking into account the socio-technical system and maintenance organization within which they lie.
The analytical framework was inspired by the Hale's maintenance management model and the Reason's model of the organizational accident. Referring to Hollnagel, this framework has been adapted to allow normal real maintenance activities to be processed. In order to gain a better grasp of the complexity of the socio-technical systems, it has also be supplemented by taking into account the maintenance organizational modes, which determine maintenance task allocation and the distribution of real activities between the different types of staff.

Methods
Ergonomic analyses of the maintenance activities were conducted in a subcontracting public transport company, which outsources some maintenance work. The methods were the following:
 semi-structured interviews with the maintenance manager, designed to identify the network of companies involved in vehicle maintenance and their relationships;
 equipped observations of the activities of internal "flying technicians" and their interactions with others; these mechanics intervene on the bus network, when defects are reported by drivers to regulators (immediate corrective interventions);
 concomitant verbalizations of the technicians throughout the observations in order to obtain explanations on their activities in progress.
Data processing consisted of content analyses of the interviews with the maintenance manager; a characterization of flying technicians' activities (analyses of the succession of their activities, analyses with respect to the interventions diachrony); clinical analyses of some interventions, during which internal technicians were in contact with outside personnel.

Results and discussion
The results highlight a complex network of companies involved in maintenance activities, a substantial number of work interruptions and a significant fragmentation of the internal technicians' activities that can be cognitively costly, reduce anticipation possibilities and lead to incidents or accidents. They also underline internal technicians' contributions to the completion of outsourced interventions and interdependence relationships between the activities of the internal and the external technicians.
Outsourcing maintenance interventions thus raises the question of risks associated with the interdependence of actual work activities undertaken by the different types of staff, since they contribute to the same maintenance intervention. This study therefore pinpoints the need to integrate inter-organizational interactions in order to understand the variability of maintenance activities, and its relationships with reliability and safety.