Variable Demand

Variable Demand

Our Expertise

Variable Demand Models (VDM) integrate modelling of the road, public transport and active travel networks to predict travel patterns. VDMs typically answer questions such as:

  • how many houses, people and jobs will locate in each area of the model in the future?
  • how many journeys will be made from each area in the model?
  • where will these journeys go?
  • at what time of day?
  • by which mode (car, public transport, walking, cycling, etc)? and
  • where will drivers park and would they use park-and-ride?

VDMs can offer insights including:

  • how will changes in travel costs and congestion shape travel patterns in the future?
  • will a new public transport of road infrastructure affect congestion and the environmental?
  • how successful will an improvement in public transport or active travel be in reducing car use?
  • what impacts would a change to parking supply, costs or strategy have?
  • how would a clean air or road user charge affect car travel, uptake of public transport and the overall quantity and distribution of travel?

SYSTRA has been at the forefront of variable demand modelling since it’s first study in the UK in 1968: the Tyne and Weir Transport Study which ultimately led to the region’s metro system. Subsequently we helped shape best practice including major roles in UK government’s seminal 1994 Report on Trunk Roads and the Generation of Traffic, and the Guidance on Multi-Modal Studies which was the basis of the current definitive TAG guidance.

We continue to push the boundaries of variable demand modelling including

  • long standing role advising Irish Government on its modelling systems
  • advising on the potential for innovative Activity Based Models which provide for detailed representation of the choices that households make in scheduling their daily lives and journeys
  • developing the open-source Quetzal VDM package in Python.

Our experts are skilled in all major VDM software packages including CUBE, EMME and VISUM; and have developed bespoke software using Python and other scripting tools.

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