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PRISM-West Midlands


"PRISM (Policy Responsive Integrated Strategy Model) has been developed by Mott MacDonald and RAND Europe as a strategic model for the West Midlands, supported by the 7 district authorities, Highways England and Transport for West Midlands. The model is a state of the art disaggregate demand model, with significant detail in zoning and networks.".
PRISM guide

PRISM covers the West Midlands metropolitan area in about 1,000 zones, with a detailed network description of the highway and public transport networks. The model operates in the VISUM software, and represents in a detailed manner the following travel responses to congestion, investment and policy:

  • change in trip making
  • change of destination;
  • change in mode;
  • change in time of travel; and
  • change in route.

The model is a disaggregate travel demand model, based on principles applied previously in cities such as Paris, Copenhagen and Sydney. The key difference with traditional modelling techniques is that PRISM takes the individual traveller as the decision maker, rather than relying on zonal proxies. The main advantage of this approach is that the model is more reliable and robust.

Because of the detail in the representation of population, the model can forecast the impacts of socio-economic and demographic developments on travel patterns, and distinguish the impacts of policies on different social grouping.

WM Map   WM 30Min Isochrone

Typical model outputs available to the end user are for base year 2011 and for reference years 2021 and 2031:

  • matrices (994 zone level) of zone to zone trips (4 periods, 24 hour, for car driver, car passenger, public transport user (3 modes; rail, metro and bus), slow modes, HGV and LGV separately;
  • these matrices can be subdivided further (if required) by purpose;
  • matrices (994 zone level) of skimmed travel times, distances, generalised costs;
  • network results for the whole PRISM network of link flows, congestion, travel times and speeds(in Mapinfo, CSV, or Access format);
  • these matrices and network results can be cordoned to a smaller area as required;
  • the matrices can be produced in TUBA format, if so required;
  • mode split tables by mode and purpose;
  • trip length distributions as required;
  • desire lines and public/private isochrones to centres as specified;
  • colour coded congestion indicators (actual/free flow time) for specified links;
  • public/private mode share to specified centres; and
  • population within pre-specified bandwidths.

In certain cases processed basic survey data can be made available, for example from roadside interviews. In model estimation and application extensive use is made of some 17,000 household surveys and roadside interviews at around 200 sites, in addition to public transport surveys, freight surveys and parking surveys, carried out between 2010 and 2012.

The new PRISM model has been designed to support the assessment of the following issues:
  • LTP submissions and targets;
  • Metro extensions;
  • Park and Ride;
  • ATM and widening;

An important role will be that of a database of travel movements, as input to more local models, including microsimulation. It is intended that any project in the West Midlands that requires modelling support will use PRISM, either as the database of network detail, planning data or travel demand patterns, or as a fully functional tool. The database may be more useful for smaller scale studies, for which cordoned networks and/or matrices can be generated for the years 2011, 2021 and 2031, whilst the full model specification becomes more relevant when forecasting the impacts of strategic schemes into the distant future. The model interfaces directly with PTV VISSIM microsimulation software. Access to PRISM is through the Joint Application Team, located in Mott MacDonald's central Birmingham Office.

The team consists of staff members from Mott MacDonald and RAND Europe. The team skills are such that a variety of requests can be dealt with, such as data extraction, model application and interpretation and general advisory work.

PRISM Management Group

PRISM has been developed on behalf of CEPOG (Chief Engineers and Planning Officers Group of the West Midlands) and the Highways England, with CENTRO contributing in kind through data and staff time.

The development of PRISM was initiated and has been overseen by a Project Management Group (PMG).

The PMG is involved in the decisions regarding model development, maintenance and cost control. Regular meetings are held to review progress on model development and applications.

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