The GM local authorities undertook a process to identify and assess the interventions that could be implemented to reduce annual mean NO2 concentrations on the roads they manage, following Government guidance.
The Strategic Case of the Outline Business Case (OBC) set out a robust case for change, based upon local modelling. It revealed a much wider problem with current NO2 levels at the roadside than initially identified by Government. It sets out the approach GM took to identifying a preferred option for achieving compliance. As part of this process, GM identified a number of possible solutions, which were assessed against primary and secondary success criteria based upon modelling and analysis; engagement with stakeholders and professional experts, and the use of a Multi-Criteria Analysis tool to assess the performance of each option against the success factors and relative to each other. A full economic appraisal was then undertaken of the best performing options. More detail is available in the Options Appraisal Report, Appendix 1 to the Strategic Case.
Following extensive analysis of the shortlisted measures, GM concluded that a charging CAZ C across the region (with supporting measures) is necessary in order to achieve compliance in the shortest possible time. Further detail is available within the Strategic Case of the OBC and in the Options Appraisal Report . The conclusions set out in the Strategic Case are consistent with Government guidance setting out a charging CAZ as the measure most likely to achieve EU Limit Values for NO2 in towns and cities in the shortest possible time, and as the measure against which all other options must be benchmarked.
GM has identified a preferred option based on which of the best performing options delivers compliance in the "shortest possible time" and that improves air quality with the least detrimental impact on GM. A GM-wide Clean Air Zone is required to deliver compliance.
This means GM has taken account of its wider responsibilities to its people and businesses and has sought to develop proposals that bring the most benefit, with the least negative impact. In particular, evidence suggests that some of GM’s most vulnerable residents are most likely to suffer the effects of poor air quality. This plan improves air quality for those residents without damaging their quality of life in other ways.
More information can be found here: GMCAP Response to Consultation Report v1 (ctfassets.net)