Will Clean Air Zones Work?

Bath and North East Somerset (UK) council commissioned a two week Automatic Number Plate Recognition Camera Survey using 45 cameras running Oct 31st to Nov 13th 2017 of the city of Bath in preparation for the introduction of a legally required Clean Air Zone as 60 other cities in the UK are looking at.

sites
Camera sites, two cameras at each site.

The 14 days of data was anonymised and released to the general public in co-operation with Bath Hacked and the council’s Environment team.

Calculations of NOX (Nitrogen Dioxides) were done using COPERT2016 data and an ‘average’ for each vehicle.

The amount of pollution an average vehicle of a specified type produced during the study in relation to 1 average free petrol car.
The amount of pollution an average vehicle of a specified type produces driving 1km to 1 average free petrol car.

Some key information

  • Bath is a small city of 90,000 residents
  • 384,591 unique vehicles were seen in the city in a two week period.
  • 8.7Million kilometres were observed. Actual number would be higher given that cameras would not detect all local journeys.
  • It’s difficult to quantify how bad a certain volume of Nitrogen Dioxide is. So I used Petrol Car equivalence.

What vehicles will be affected by the Clean Air Zones?

Local authorities can decide what level of restriction to apply. There are four classes of Clean Air Zone:

  • Class A – Buses, coaches, taxis and private hire vehicles
  • Class B – Buses, coaches, taxis, PHVs and heavy goods vehicles (HGVs)
  • Class C – Buses, coaches, taxis, PHVs, HGVs and light goods vehicles (LGVs)
  • Class D – Buses, coaches, taxis, PHVs, HGVs LGVs and cars

Buses, coaches and HGVs that meet Euro VI emissions standards must be exempt from any charges or restrictions. Cars, vans and taxis that meet Euro 6 (diesel) or Euro 4 (petrol) emissions standards must be exempt from any charges or restrictions. Ultra-low emission vehicles with a significant zero-emission range must be exempt from and charges or restrictions.

Bath has decided to go for Class D.

Some observations

  • Older Buses produce a lot of NOX but they also are on our roads rather a lot.
  • A new diesel car is still 30 times worse than a new petrol car.
  • CO2 emissions for HGVs/Buses should be taken with a pinch of salt. I need to investigate.
  • It is clear that CAT6 DIESEL VANS and CARS should NOT be excluded from the CAZ charge. Older models are terrible, new models are still terrible. There should be a big push to petrol cars and vans only within cities.
  • Freight consolidation focuses on HGVs in cities. We should be focusing on Amazon delivery consolidation, and a shift to using electric cargo bikes for deliveries within cities, particularly ones as small as Bath.

Conclusions

I really want to repeat the point that DEFRA specified the bands available for a city to choose from. DEFRA has allowed diesel cars and vans to be exempt despite them 30 to 70 times worse than a petrol car. Think about this, a modern diesel car is twice as bad as a modern diesel truck or bus when it comes to NOx emissions. Diesel Cars and Vans should not be in cities, no matter how new.

Thread is available on reddit as well.

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