Small group of workers (4 dispatchers and 2 supervisors), Location within a site with co-location at desks. Ability to oversee and overhear one another. Focus on the use and reconciliation of various screens representing different details of the deployment of ambulances to incidents across the region. These include:
1. Vehicle statuses and placement in the region - the Vehicle Availability Map (VAM) 2. Incident descriptions and details - The Incident Stack 3. Information from a Global Positioning Satellite (GPS) system - the Automatic Vehicle Location System (AVLS) 4. Screen for selecting ambulances - Dispatch Selection Screen
The focus is on four representations used in the work; the 'Incident Stack', the 'Dispatch Selection Screen', the VAM and the AVLS'. The Incident Stack is a textual display that shows details of all incidents both waiting to be assigned and active. The active incidents contain extra information such as the ambulance call signs and the as-the-crow-flies distance of the ambulances from the incidents (provided by the AVLS). The Dispatch Selection Screen comes into play when a dispatch operator selects an incident from the 'Stack'. This screen displays the selected incident as well as a list of ambulances with the nearest free ambulance highlighted. Selecting an ambulance on screen forwards the details to that crew. The VAM (see below) is crucial for seeing what the load is on the service. It displays a series of lists for all the ambulances in the region. The lists consist of the call signs for ambulances and are placed in a quasi topological arrangement under abbreviations for areas in the region such that two consecutive lists correspond to two adjoining areas. Ambulances are highlighted as to whether they are active, available and so on. The VAM provides a information on both the status of ambulances and also the current situation by area and as a whole. This allows workers to see problems developing and to relocate ambulances from quieter areas to those under strain. These displays are accessible through dispatcher's terminals but also the Stack and the VAM are displayed on two large monitors. While the AVLS provides as-the-crow flies distance and the estimated times of arrival (ETAs) to incidents its display showing ambulances on a map of the region is not (see below) Ambulance control relies primarily on numerical distance and whether an ambulance is free or not Other representations are also employed in the assigning of incidents and managing ambulance control It is the combination of different representations of work that allows dispatch operators to both make individual dispatch decisions and to observe, manage and plan for the region as a whole.
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The AVLS is seldom used as a display for understanding the stiuation in the region while the VAM is crucial for control
Coordination is achieved through individual and group orientation to the different representations of work and other's interaction with them. For example, understanding the impact of a dispatch decision of another dispatcher as shown on the VAM may influence the decision as to which ambulance a dispatcher may select from the dispatch selection screen. As well as coordinating through the system, by comparing and juxtaposing representations workers explicitly use the multiple representations as resources for direct verbal interaction in order to discuss enact and plan control decisions. The display of the VAM and Incident Stack on large monitors allows for coordination around these two shared representations.
Inter-organisational group of workers (4 dispatchers and 2 supervisors) in an ambulance control room.