The STM contains a package of tools which provide the functionality to develop and deliver appropriate operational strategies for almost any urban, inter-urban or rural situation.
Although the concept of STM was bourne out a desire to maximise the potential for providing bus or tram priority in co-ordinate networks, the flexible nature of this system has allowed it to be utilised as a platform for achieving a multitude of control strategies such as traffic gating or queue management.
The STM should be considered as two distinct components. These are referred to by the manufacturer as a Client Based Element and a Server Based Element
The STM is a strategic tool which can collect, collate and store traffic data or it can be used for the manipulation of any traffic signal controlled intersection connected to a UTC Database. This includes junctions operating Fixed Time UTC, SCOOT UTC, MOVA or Vehicle Actuation.
The Client Based Element is an Offline Development Tool (ODT) for the formulation of priority strategies. The ODT uses a bespoke programming language (MERV code) to introduce a fixed time plan or series of plans which manipulate the traffic signal timings to provide priority to selective vehicles and where necessary compensate opposing vehicles for any delay incurred.
The logic based system allows for a seamless transfer between predetermined plans avoiding “crash changes” such that most drivers are almost unaware anything unusual has occurred.
The Server Based Element is the live system which interacts with other servers (or emulated systems when testing new strategies). This server based element consists of a Database, the STM, UTC Interface, AVL Interface, GUI Interface and Monitoring capability.
The STM is therefore connected directly to the UTC server and obtains live information for each intersection such as Cycle Time, Time in Cycle, Control and/or Reply Bit patterns.
The STM can also be connected to vehicle location systems such as the ACIS “Your Next Bus” system in Sheffield. Information is fed through an XML gateway directly into the STM allowing priority interventions to be based on specific buses as they travel around the network.