Exclusive: Average speed cameras cut Welsh air pollution by half

14/10/2020 | RHODRI CLARK

Highways can reveal that air pollution at roadside hotspots reduced dramatically after the Welsh Government began enforcing lower speed limits with cameras.

The figures, obtained by a Freedom of Information request, show that pollution levels fell by almost half on some parts of the Welsh trunk road following the installation of average speed cameras.

The lessons may be valuable to Highways England as it trials reduced speed limits on sections of its network to bring Nitrogen Dioxide (NO2) concentrations within legal limits.

The Welsh Government introduced mandatory 50mph speed limits on five trunk-road sections in June 2018, specifically to reduce air pollution in neighbouring built-up areas.

Many drivers treated the limit as optional, even after the Government resorted to putting up signs explaining that slowing down would improve local air. Mean speeds through four of the sections ranged from 55mph to 58mph during the first year of the 50mph limits.

In summer 2019, average speed cameras and signs were installed. Now an FOI release reveals that NO2 concentrations beside the A470 between Upper Boat and Pontypridd were 82.0 μg/m3 in February 2018 and fell to 78.6 μg/m3 a year later (with the 50mph limit in place) but by February 2020 concentrations were just 43.2 μg/m3 – or 47.3% lower than in February 2018.

Data after February 2020 were not requested, to ensure comparisons were not influenced by COVID-19 travel restrictions.

From February 2018 to February 2020, other NO2 reductions were 41% on M4 J25-26 at Newport; 39.5% on M4 J41-42 at Port Talbot; 22.4% on A494 at Deeside; and 32.3% on A483 near Wrexham.

In all cases, the reduction mostly occurred after average speed cameras were installed.

In February 2020, more than 92% of vehicles complied with the 50mph speed limits at Port Talbot and Wrexham (both directions) and westbound at Deeside. The lowest compliance was 81.1% westbound at Pontypridd.

Compliance data for the M4 at Newport was not available.

Highways InProfile

latest magazine issue
Highways jobs

Traffic Management Technician - WMF2240e

£28,598 - £29,540
Westmorland and Furness Council is seeking a committed and technically capable individual to join our Traffic Management Team Kendal, Cumbria
Recruiter: Westmorland and Furness Council

Senior Technician-Road Closures

£35,422 - £38,730
The Network Planning division is seeking to appoint someone who is enthusiastic and a team player Derbyshire
Recruiter: Derbyshire County Council

Technician - Road Closures (2 Posts)

£29,719 - £31,691
The Network Planning division is seeking to appoint someone who is enthusiastic, an excellent team player Derbyshire
Recruiter: Derbyshire County Council

Structures Inspector

£Competitive
We are excited to offer a fantastic opportunity for two Permanent Structure Inspectors to join our dynamic SBIM team Bristol
Recruiter: Amey

Highways Maintenance Operative

£Competitive
We have fantastic opportunities for a permanent Highways Maintenance Operatives Kettering, Northamptonshire
Recruiter: Amey

Site Manager

£Competitive
We are excited to offer a fantastic opportunity for a Permanent Site Manager Bristol
Recruiter: Amey

Principal Commercial Manager

£Competitive
The SBIM contract involves delivering inspection and maintenance programmes for National Highways Bristol
Recruiter: Amey

Senior Commercial Manager

£Competitive
We are excited to offer a fantastic opportunity for a Permanent Senior Commercial Manager Nottingham, Nottinghamshire
Recruiter: Amey

Highways Maintenance Operative

£Competitive
We have fantastic opportunities for a permanent Highways Maintenance Operatives. Northampton, Northamptonshire
Recruiter: Amey

Managing QS

£Competitive
In this role, you will support the Senior Commercial team in the end to end commercial process for the Area 12 contract. Yorkshire and the Humber
Recruiter: Amey

Highways Inspection Officer

£32,962 - £36,791 per annum
We have an exciting opportunity for a Highways Inspection Officer to join us! Windsor, Berkshire
Recruiter: The Royal Borough of Windsor & Maidenhead

Highways Technical Assistant

£29,064 - £31,537
Are you looking for a varied role in a dynamic and innovative team environment that can make a real difference to North Yorkshire’s highways? Leeming Bar, Northallerton
Recruiter: North Yorkshire Council

Street Lighting Electrical Inspector

£34,434 - £38,220 per annum
Do you hold an ONC in electrical engineering or City & Guilds Electrician? Northallerton, North Yorkshire
Recruiter: North Yorkshire Council

Senior bridge Engineer - WMF2212e

£47,181 - £48,226
You will be the key responsible engineer for this area and will also provide technical advice and guidance to our team Cumbria / Various
Recruiter: Westmorland and Furness Council

Civil Enforcement Officer - WMF2221e

£28,598 - £29,540
Are you seeking an active and challenging role, part of a friendly and welcoming team? Kendal, Cumbria
Recruiter: Westmorland and Furness Council

Bridge Engineer - WMF2219e

£42,839 - £44,075
We are currently seeking to recruit an experienced and enthusiastic Bridge Engineer Kendal, Cumbria
Recruiter: Westmorland and Furness Council

Senior Public Transport Officer

£42,839 - £46,142
We are looking for an experienced public transport professional to become our Senior Public Transport Officer. Northamptonshire
Recruiter: North Northamptonshire Council

Principal Transport Planner (Strategy) (Fixed-Term)

£48,226-£51,356
We are looking for an experienced professional to join as a Principal Transport Planner (Strategy) Northampton, Northamptonshire
Recruiter: North Northamptonshire Council

Mobile Street Scene Operative

£24,796 to £25,989 per annum
The Waste and Street Scene department requires enthusiastic and committed mobile street cleansing operative. Northallerton, North Yorkshire
Recruiter: North Yorkshire Council

Senior Technician - Highways Design (2 Posts)

Grade 10 £35,422 - 38,730 per annum
An exciting opportunity has arisen within the Professional Services Section Derbyshire
Recruiter: Derbyshire County Council
SUBSCRIBE NOW

Latest Video

Subscribe to Highways today to ensure you keep your finger on the pulse of everything happening in the UK road network throughout the year.

SUBSCRIBE NOW