Introduction

Background

The Scottish Government has set climate change ambitions to become a net zero greenhouse gas (GHG) emitting nation by 2045. This ambitious target requires a collective effort from all corners of society and carbon saving opportunities are being explored to meet this goal. The transportation sector is responsible for a significant share of CO₂ emissions and is regarded as one of the key areas where carbon emissions can be reduced.

There has been a growing interest worldwide to understand how rolling resistance affects carbon emissions. It is understood that by reducing the rolling resistance of road surfaces, vehicle fuel consumption can be lowered and hence CO₂ emissions. In theory, small reductions in rolling resistance, particularly on busy roads, could result in a significant reduction in carbon emissions. However, the measurement and modelling of rolling resistance is known to be complex and a balance needs to be struck between the investment or cost of specifying new materials versus potentials savings in CO₂ emissions. Similarly, possible side effects of reducing rolling resistance need to be considered to ensure road safety is not compromised.

Scope

The Scottish Road Research Board (SRRB) commissioned WSP to undertake an international literature study of published work relating to rolling resistance. The study is regarded as a scoping exercise to understand the potential benefits of developing this area of interest and whether additional work is required.

The brief requires a search to be undertaken for papers and articles that relate to the following areas:

• Road surfaces with low rolling resistance.
• Lower fuel consumption and carbon savings related to low rolling resistance.
• Pros and cons associated with specifying low rolling resistance, including safety issues.
• Particulate emissions.
• Level or scale of reductions that may be achievable.