network image

SATURN This software currently provides the basis of the Greater Manchester Strategic (Highways) Model. We have worked with the developers of the software since its early inception, including providing an early scheme example test bed for the modelsSATURN calibration. Our GMSM represents the whole of the Greater Manchester highway network at the detailed “simulation” level of representation. All motorways and A- and B- classification roads, as well as other unclassified roads deemed of local traffic significance are represented. Simulated junctions replicate actual methods of traffic signal or priority control, and characteristics such as lane usage and competing vehicle movements to determine practical capacity and delays under changing vehicle flow circumstances. Beyond GM the national network is also depicted but with a reducing level of detail with increased distance and remoteness from GM. Our “networks” include details of prevailing scheduled bus service routes and frequencies, and are set up to represent average October weekday morning and evening peak periods (hours) and an average inter-peak hour. This supply side information is combined with travel demand to create traffic assignments and so estimates of traffic flow. The process is validated to existing conditions and then used in conjunction with travel demand mode shift analysis to anticipate other scenarios, including revised demand due to development and or changes over time as we look at future aspirations. Cut down, or “cordoned”, versions of the GM-wide model are frequently used to consider more local applications, such as the Ashton Northern Bypass, Cross City Bus and SEMMMS. We also use even more detailed (but also more data hungry) microsimulation models for this purpose, such as the “PARAMICS” software as described below.

PARAMICS In recent years, the use of micro-simulation modelling has become more widespread. It is widely recognised that the graphical presentation of model outputs available from this type of model have significant practical use in conveying scheme impacts to a non-technical audience; which can of course be invaluable in public consultation. In technical terms a fundamental advantage to transport practitioners is that the models can provide detailed assessment of the interactions between individual vehicles, acknowledging a range of different vehicle characteristics and driver behaviours, as well as replicating actual forms of traffic signal controller and strategies. This makes it particularly suitable as a tool to aid in the design of complex junctions and detailed traffic management plans. We have extensive experience in the development and application of micro-simulation modelling techniques. Currently we use PARAMICS software, ranging from models of single (complex) junctions through to larger networks that include route choice.

Bolton Town Centre… An example of a larger model is the Paramics model we built of the “south sector” area of Bolton town centre. We were commissioned by Bolton Council to provide traffic forecasts to inform the design for a proposed link road between Moor Lane and Trinity Street, in conjunction with traffic management proposals associated with the development of the Bolton One complex. As these proposals were part of a larger package of changes throughout the town centre, we estimated the wider re-assignment impacts of the strategy using a Saturn model of the town centre. These changes were then incorporated into the more detailed Paramics model of the area affected. A particular concern was the impact of the proposals on access to the existing Morrisons store on Black Horse Street. We were able to work with Bolton’s highway designers and colleagues in GMUTC to use the model to examine a number of different junction layouts and to fine-tune the design of the scheme, to minimise these impacts.

Prestwich... The Prestwich model was developed for Bury Council to inform their consideration of a masterplan and redevelopment proposals for the Prestwich Village area. The model is the largest we have yet produced, incorporating key sections of two major radial routes linking Bury with Manchester City Centre and a key junction on the M60 motorway, in addition to the Village centre and its associated car parks.