UK transport carbon model: reference guide

Current debate focuses on the need for the transport sector to contribute to more ambitious carbon emission reduction targets. In the UK, various macro-economic and energy system wide, top-down models are used to explore the potential for energy demand and carbon emissions reduction in the transport sector. These models can lack the bottom-up, sectoral detail needed to simulate the effects of integrated demand and supply-side policy strategies to reduce emissions.

Bridging the gap between short-term forecasting and long-term scenario “models”, the UK Transport Carbon Model (UKTCM) is a newly developed strategic transport, energy, emissions and environmental impacts model, covering a range of transport-energy-environment issues from socio-economic and policy influences on energy demand reduction through to lifecycle carbon emissions and external costs.

This reference guide describes the model in detail, including functional relationships, data flows and main data sources.

What is the UK transport carbon model?

Built around a flexible and modular database structure, it simulates future transport supply and demand, for all passenger and freight modes of transport, and calculates the corresponding energy use, life cycle emissions and environmental impacts year-by-year from its base year of 2012 to 2100 and beyond.

It takes a holistic view of the transport system, built around a set of exogenous scenarios of socio-economic, demographic and cultural developments. The model is technology rich and, in its current version, provides projections of how different vehicle technologies evolve over time for 770 vehicle technology categories, including 283 car technologies such as increasingly efficient gasoline internal combustion engine vehicles, battery electric vehicles, plug-in hybrid electric vehicles and hydrogen fuel cell vehicles.  An overview of the model has been published in Brand et al. (2012).

What can it be used for?

TEAM was designed to explore alternative transport futures to meet carbon mitigation, air quality and energy policy goals. Analysts and decision makers are able to systematically compare a wide range of scenarios and policies, including those focusing on travel behaviour and demand, vehicle ownership and use, fiscal, pricing, eco-driving, fuel obligations, speed limits, technology investment/procurement, ‘official’ vs ‘real world’ gaps, and urban area access restrictions. It provides estimates of the full environmental consequences, including pollutant emissions by source, by end user, domestic and ‘international’, targets vs. cumulative, and so on.

Uncertainty in the outputs is typically assessed by conducting sensitivity analyses around the central estimates or, if time permits, more sophisticated Monte Carlo simulations.

Use in strategy and policy analysis

UKTCM has been applied in policy and strategy analysis, playing a key role in:

Exploring contrasting futures for Scotland that compare transport-related ‘lifestyle’ changes and socio-cultural factors against a transition pathway focussing on transport electrification and the phasing out of conventionally fuelled vehicles (Brand et al., 2018)

• Developing the Energy 2050 ‘lifestyle’ scenarios for UKERC (Anable et al., 2011; Anable et al., 2012);
• Integrating consumer segmentation and a heterogeneous car market to a whole systems model (Brand et al., 2017)
• Exploring the effectiveness of low carbon car purchasing incentives in the UK (Brand et al., 2013);
• Exploring motorway speed limits and CO2 impacts (UKERC policy brief);
• ‘Dieselgate’: AQ and CO2 trade-offs and co-benefits of emissions mitigation policy (Brand, 2016);
• Contributing to the UKERC submission to the House of Commons Energy and Climate Change Committee’s Second Report of Session 2016–17 of the 2020 renewable heat and transport targets.

UKTCM was further developed and used in developing low carbon urban freight scenarios for UKERC project ‘adVANce’: carbon emissions reductions for vans (2016-2018).