SPRUCE Architecture
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The system is synchronized to the UTC computer, and when controlling signals on-street it monitors detector inputs, processes logic, runs plans, and outputs the necessary stage forces every second.
The SPRUCE server communicates with the main UTC server and at times will override the main UTC plan in order to optimise the on street traffic network.
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Comprehensive capability including:
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Can monitor all controller reply bits as a basis for making a range of informed timing interventions (or storing for historic data collection),
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Can override normal UTC plans with different synchronized plans (e.g. 'priority' or 'compensation' plans),
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Can alter timings in a variety of different ways ('extensions', 'recalls', 'holds', 'short term offsets', 'cumulative offsets' etc.),
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Can 'pick up' controllers from VA, and provide priority timings via UTC before 'dropping back' to VA,
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Can insert 'advance' controller demands (or similar bits) from detector points upstream of local detection.
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The architecture of the developed version of SPRUCE is based around an SQL database. This stores data required to run: node configurations, plans, AVL (Automatic Vehicle Location) detector inputs, and the programmable logic that drives the system. The system is synchronized to the UTC computer, and when controlling signals on-street it monitors detector inputs, processes logic, runs plans, and outputs the necessary stage forces every second. There are now interfaces to both Peeks and Siemens UTC systems.
Graphical User Interface (GUI)
A GUI is provided to enable the user to both monitor and influence SPRUCE run-time operation. Each GUI is created by the user and can show any parameter available within the SPRUCE logic.
Off line Development Tool (ODT)
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The actually SPRUCE SPRUCE software comes with no strategies built into it - much like a software package like Microsoft Excel comes with blank sheets and provides a user with the means to write powerful applications. The main strength of SPRUCE SPRUCE is this freedom to allow an engineer to implement any strategy they can conceive of.
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The way an Engineer writes their strategies is via the 'Offline Development Tool' and again much like a package like Excel - the ODT is ‘cell based’ tool which allows Excel Boolean style statements to be coded into strategies. An SPRUCE SPRUCE strategy is written offline but can be modified and re-implemented to street within minutes which means that fine tuning of strategies can easily be done.
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This means it is very powerful and can be used to solve complex problems. Not all strategies need to be complex though and there is now a growing ‘library’ of strategies ranging from simple linking strategies, bus priority, Fire Service Green Wave etc that can be used a templates in other locations.
