Case Study - Highways Agency: Development of the Network Performance Model

Client: Highways Agency
Sector: the transport sector, central government

HA use of the model

The network performance model (NPM) was developed for the Highways Agency (HA) by Risk Solutions. It is a software model that supports analysis of traffic performance on the strategic road network (SRN). It is routinely used by the HA national intelligence unit (NIU) to support their analysis of network performance.

The nature of this model is that it can be calibrated to generate and store speed-density curves for road links of the Agency's network. A stochastic process can then be used to derive expected performance characteristics of these links. The most frequent use of the model is to predict the likely characteristics of a road link's performance, fed with recorded observed data such as traffic flows and journey times. This is particularly useful for informing the Agency about road performance characteristics that are infeasible to observe directly, such as which parts of the road were in congested flow at any time, given overall measurements of speed and flow.

The Agency uses this type of analysis to characterise the past performance of its roads, as well as to project scenarios about the future.

Development plans

The NIU have identified certain aspects of the NPM that need to be updated and which could be improved. These include:

  • Introduction of a facility to test whether or not a speed restriction has been introduced for road works.
  • Incorporation of a facility for calculating link transit reference times.
  • Introduction of a feature to allow road capacity to be evaluated.
  • Consideration of future data needs for smart motorways.

Risk Solutions has been commissioned to support the HA in this work.