Question to the Department for Transport:

To ask the Secretary of State for Transport, what scenarios have been run under the National Transport Model in the last five years.

The National Transport Model (NTM) is used by the Department for Transport to analyse possible future travel behaviour, and so to inform investment and policy decisions. Scenarios are a method used by analysts to understand uncertainty, taking different inputs and assumptions into the modelling.

One use of the NTM is to provide the projections for the Department’s regular publications, most recently the National Road Traffic Projections 2022. The NTM was used to run a Core Scenario and seven Common Analytical Scenarios. These scenarios have been created to explore key drivers of uncertainty on transport demand, including the economy, decarbonisation, behaviour and technology. Full descriptors of these scenarios can be found in DfT’s Uncertainty Toolkit as well as in the National Road Traffic Projections report. The outputs of these runs are also in the report, as well as published data files on the same webpage.

Prior to the National Road Traffic Projections, the Department published the Road Traffic Forecasts in 2018. These included scenarios that have since been superseded by the Common Analytical Scenarios, but were an improvement on previous publications. These scenarios explored GDP, fuel price, migration, behaviour and decarbonisation of vehicles. The full descriptions of these scenarios, as well as the outputs from the modelling, are published in the report and associated data tables.

In addition to the Department’s regular publications, the NTM serves as an invaluable departmental analytical tool. As with many other models, it is used to inform policy decisions, as well as undertaking exploratory analysis to understand possible impacts of in areas the Department know to be significant in travel behaviour (for example, changes in GDP projections).