Asked by: Lord Campbell-Savours (Labour - Life peer)
Question to the Department for Transport:
To ask His Majesty's Government whether they have made an assessment of the effects of (1) vehicle speeds, and (2) journey times, on emissions in urban areas; and if so, whether higher (a) vehicle speeds, or (b) journey times, have a greater effect on emissions levels.
Answered by Baroness Vere of Norbiton - Parliamentary Secretary (HM Treasury)
The Government has commissioned studies to assess the impact of vehicle speed on emissions, for example undertaking a high-resolution emission modelling approach to understand changes in vehicle speeds and how it relates to emissions. The Department uses the best available evidence to model emissions in urban areas, including evidence linking vehicle speeds with emissions based on international guidelines. The evidence is that the factors influencing emissions are complex and the relative impact of vehicle speed, acceleration/deceleration and distance travelled (which are all related to journey times), will vary depending on the local situation.
In addition, the Government’s Joint Air Quality Unit helps local authorities to calculate NOx emissions in their local areas using outputs from traffic models, which use a range of parameters including speed and distance travelled (which influence journey time) and the number of vehicles. The results of these parameters are contained in their Full Business Cases which are all published documents.
Asked by: Lord Campbell-Savours (Labour - Life peer)
Question to the Department for Transport:
To ask His Majesty's Government what assessment they have made, if any, of the effects of low emission zones in urban areas on (1) vehicle usage, (2) average vehicle speeds, (3) average vehicle journey times, (4) emissions levels, and (5) overall air quality.
Answered by Baroness Vere of Norbiton - Parliamentary Secretary (HM Treasury)
The Government has commissioned a robust evaluation programme for the collection and analysis of air quality, traffic, and behavioural insights data from Local Authority areas implementing measures for the reduction of nitrogen dioxide (NO2). Case studies give further understanding of how local plans are affecting local groups and businesses.
The Government has published a series of annual reports which set out and discuss the analysis of these evaluation findings. Headline findings from these reports and other analyses give an insight into the effects of Clean Air Zones and other measures on air quality and vehicle fleets in Local Authorities. The 2021 annual report is available to view on the Defra Science Search - AQ0851.
Asked by: Lord Campbell-Savours (Labour - Life peer)
Question to the Department for Transport:
To ask Her Majesty's Government what evidence they use to inform policy about vehicle (1) speed limits, and (2) emissions; and what assessment they have made of the emissions levels of (a) petrol, and (b) diesel, vehicles between 1,000–3,000cc travelling at a constant speed of 20mph in (i) first gear, (ii) second gear, (iii) third gear, (iv) fourth gear, (v) fifth gear, and (vi) sixth gear.
Answered by Baroness Vere of Norbiton - Parliamentary Secretary (HM Treasury)
The aim of speed management is to deliver a balance between safety objectives for all road users and mobility objectives, to ensure efficient travel, as well as environmental and community outcomes. The Department has published guidance designed to make sure that speed limits are appropriately and consistently set while allowing for flexibility to deal with local needs and conditions.
The regulatory emissions tests for type approval of new vehicles are conducted under dynamic rather than constant speeds in order to be more representative of real-world use. The Department does not have specific results for the situations outlined. Transport emission factors are used within the National Atmospheric Emissions Inventory to provide information on the emissions of vehicle fleets based upon factors such as their average speed, fuel type and engine capacity. These are also used within the Emissions Factor Toolkit, published by DEFRA, to assist local authorities carrying out assessment of local air quality.