17/06/21

When making a decision on reducing air pollution on Castle Street the council has a number of factors which need to be carefully balanced - including:

 1.   Will the clean air plan for Castle Street see pollution levels on this mainly non-residential street brought within legal requirements?

2.   Could cutting numbers of general traffic on Castle Street lead to traffic numbers rising in surrounding streets, pushing pollution levels up in areas which have more residential properties than Castle Street?

The council was looking at two options to improve air quality on Castle Street and in other parts of the city.

Option 1: To allow a reduced number of vehicles to use the street;

Option 2: To allow only buses, taxis and cyclists to use the street.

Both of these options deliver a legally-binding requirement to reduce pollution on Castle Street to within legal limits.

Option 1 replicates the scheme included in the Council's Clean Air Plan that was approved by Welsh Government's independent expert panel and signed off by Ministers when the plan was approved in December 2019 before the pandemic struck.

However, the latest modelling, undertaken by expert consultants that specialise in transport and air quality, shows that pollution levels could rise in 34 of 42 streets and key routes into the city if cars are completely displaced from Castle Street and Option 2 was adopted by the council.

While the modelled rise in surrounding areas is within legal limits, there are clear concerns that any rise of air pollution in residential areas, in favour of achieving lower levels of pollution on non-residential Castle Street, is one that needed to be carefully considered before Cabinet took any decision. This is particularly important as many of these residential areas already have relatively poor levels of air quality.

There are also concerns around what traffic flow will look like once lockdown has been lifted and things return to normal. If we see an increase of car use, as a result of ongoing social-distancing requirements on public transport, then pollution levels in surrounding residential streets could possibly rise higher than currently projected.

Consequently the council wants to gather more data on traffic flow across the city centre as commuters return to work and visitor numbers return to normal after the pandemic. This up-to-date data on post-pandemic traffic flows will then be used to inform plans to further reduce air pollution and congestion in the city. This council is committed to improving public transport, cycling and walking options across the city making the air in Cardiff cleaner for everyone to breathe wherever they live.

Today Cabinet chose to adopt option 1 temporarily while more data on postpandemic traffic flow and air pollution across the city is gathered. This option does not see Castle Street reopen as it was pre-COVID. Two lanes will be re-opened to general traffic, with the west-bound bus lane and the two-way segregated cycleway installed during the pandemic will both remain. This should, according to modelling, and the current trend of people continuing to choose to travel by sustainable forms of transport, reduce general traffic on the street to around 50% of pre-Covid levels at peak times.

This would meet a legally-binding requirement to lower pollution on the street to acceptable limits in the shortest time possible and represents the Council's original plan for the road as set out in the Clean Air Plan produced by Cardiff Council and subsequently approved by Welsh Government in 2019.

Given the transitional nature of the scheme, Option 1 for Castle Street will not depend on Clean Air funding from Welsh Government and can be funded from existing Highways related budgets.