Analysing driver responses to expansion of the Ultra-Low Emission Zone

Transport for London (TfL) was keen understand how car users would respond to the proposed expansion of the Ultra-Low Emissions zone in London (ULEZ). The proposals, to be introduced by the end of 2019, would impose charges for older petrol and diesel vehicles over an area bounded by the north and south circular roads.

TfL’s questions concerned how drivers would respond: how many would choose to pay, or change their choice of mode and/or travel frequency? how many would sell their non-compliant cars, and when?  

In 2017 Steer carried out Online Stated Preference interviews with 1,300 respondents who owned a non-compliant car and used it to travel in the proposed ULEZ area.

The interviews addressed both short-term responses (change of mode or trip frequency) and long-term responses (upgrading their vehicle).

Successes and outcomes

The survey, with its large sample size, provided a rich database of information for TfL.

The responses to the Stated Preference questions were used to build models describing how drivers would respond to a range of future charges. These were implemented in Excel and handed over to TfL, who were then able to use them to test scenarios and provide quantified evidence to policy makers.