What assessment has been made of the 50mph zones on the most polluted roads in Wales in order to bring them into compliance with clean air zone guidance within the soonest possible time?
There are 5 locations on our motorway and trunk road network that exceed the Directive limit level for NO2 - 40 μg/m3, these include the: -
- A494 at Deeside;
- A483 at Wrexham between junctions 5 and 6;
- A470 between Upper Boat and Pontypridd;
- M4 between junctions 41 and 42 Port Talbot; and
- M4 between junctions 25 and 26 Newport.
Detailed investigations, including modelling using the approach set out in the Welsh Transport Appraisal Guidance (WelTAG), commenced in 2017 and indicate that the implementation of 50 mph speed limits at each of the locations has the potential to bring immediate improvements to air quality and bring forward compliance with the Directive.
In November 2018, we published our supplemental plan to the UK plan for tackling roadside nitrogen dioxide concentrations 2017, which confirms the measures moving forward to address air quality at the five locations. A copy of the plan can be viewed at:
https://gov.wales/docs/desh/policy/181129-final-supplemental-air-quality-plan-en.pdf.
We will be undertaking a detailed review of the effectiveness of the speed limits later this summer, once a full 12-months’ worth of data following initial implementation of the 50mph limits has been analysed.