The Impact of an Ultra-Low Emissions Zone in Central London
Paul Metcalfe, PJM Economics, Chris Heywood, Accent, Rob Sheldon, Accent
We investigate, using a stated preference survey, how London road users would respond to an Ultra-Low Emissions Zone scheme upon its introduction, and how sensitive their responses would be to a range of scheme variations.
London's air quality has improved significantly in recent years. However, it is currently in breach of European Union (EU) legal limits on nitrogen dioxide (NO2). In response to air pollution concerns, the Mayor of London announced in February 2013 his intention to create the world’s first Ultra Low Emission Zone (ULEZ) to ensure all vehicles driving in the centre of London during working hours would be zero or low emission from 2020. The ULEZ was to be aimed at reducing air quality pollutant (NOx and PM10) emissions without increasing CO2 emissions.
In this paper, we investigate how current road users of different types in central London would be likely to respond to the ULEZ scheme upon its introduction, and how sensitive their responses would be to a range of scheme variations, including differences in the compliance criteria, differences in scheme operating times, and differences in the level of charges that would be applied. A stated preference (SP) survey of 800 owner-drivers (which included cars, small vans, LGVs and HGVs) was undertaken which included two exercises: the first focused on the decision over whether or not to replace one’s main vehicle with a compliant vehicle; the second focused on what the respondent would do, for up to three specific journeys, if they had a non-compliant vehicle.
Our modelling framework uses a random effects logit specification to model the vehicle replacement choice, followed by a random parameters logit specification to model the journey behaviour choice. These models are used to generate elasticities of vehicle replacement and journey behaviour choice with respect to each of the scheme parameters and, ultimately, predictions concerning the impact of the scheme on vehicle stock projections, by class of vehicle, and on journey patterns.
Results from the analysis are intuitively reasonable. The econometric models show correctly signed effects for all variables. Furthermore, the predictions of vehicle replacement and travel behaviour impacts all show plausible magnitudes.
The outputs from the present research have been used by Transport for London, in conjunction with other commissioned research, to appraise how the proposed ULEZ scheme would impact London. The scheme details have now been published (https://tfl.gov.uk/modes/driving/ultra-low-emission-zone) and the policy will come into force in London in 2020, leading to reduced exhaust emissions of NOx and particulate matter PM10/PM2.5, and thereby making central London a more pleasant place to live, work and visit.
Association for European Transport