Is it time to ban diesel vehicles from Norwich city centre?
PUBLISHED: 13:06 30 October 2018 | UPDATED: 13:11 30 October 2018
Archant Norfolk 2018
Over recent years we’ve seen changes in Norwich city centre which have helped make it a more pleasant place.
One noticeable improvement is the reduction in through-traffic, which has allowed the development of a more coherent pedestrian-friendly area less dominated by motor vehicles.
This is part of a welcome process of re-civilisation. Streets that had over the past half-century become commandeered as dedicated highway are being reclaimed as urban space - to be shared by a wide variety of users, be they shoppers, students, business people, artists, tourists or residents.
While endemic smartphone addiction has added another dimension to street life, most people still manage to interact in a sociable way that befits a fine city.
What our eyes see is only part of the story. It is time to focus on something less visible but equally vital: what we are breathing.
In physical terms our city environment is a kind of pond in which we all live and breathe, an ill-defined air mass that sustains all those users – including vehicles and their combustion engines.
It is now more noticeable that some of these visitors are behaving in a less than civilised fashion: they pump noxious discharges into the pond right under our noses. I am referring to diesel-engined buses.
It’s ironic that a hundred years ago, when the city centre was a forest of factory chimneys and the atmosphere thick with coal smoke, Norwich boasted a public transport system that was actually emissions-free at the point of use: we had electric trams.
That lasted 35 years, before the system was taken over and shut down by Eastern Counties Omnibus Company.
Nowadays, with industry gone, our public transport provision (such as it is) is reliant on an ageing fleet of fossil-fuelled vehicles.
Each is powered by a five to 10 litre turbocharged diesel engine permanently connected to our breathing compartment by a 50mm diameter exhaust pipe.
The daily impact of buses is the legacy of 1980s privatisation and deregulation: they jostle for a share of limited road space against competing providers and other traffic. It’s a battle played out daily in Castle Meadow and elsewhere.
Those engines rarely take a break, idling in stationary traffic between short bursts of revving, acceleration and braking. Each manoeuvre accompanied by an augmented injection of exhaust gases onto the street.
So what is it we are breathing? It’s a complex mixture of gases and particles, and the way it spreads outward and upward away from the source is dependent on which pollutant we’re monitoring, the geometry of the vehicle and nearby buildings, and on the weather conditions at the time.
There is a choice between concentrating the plume at the kerbside (just where bus passengers wait), or dispersing it further afield so everyone gets a lesser dose.
Diluting nitrogen oxides was the dubious ‘air quality’ justification for recent road schemes at St Augustine’s and Grapes Hill.
Few components of our cocktail of exhaust do you any good. For some of the traditional ingredients (sulphur or carbon monoxide), you may survive the day and even recover.
For others, the effects are cumulative. In this category are the millions of tiny specks of carbon (known as particulates) that enter the body carrying other chemical nasties, and remain there doing their insidious worst. This is where the most serious health concerns lie.
What about cleaner buses? Emissions from new buses have indeed been cut progressively, from Euro I standard in 1993 through to Euro VI in 2014.
Yet the expensive technofix of adding ever more filtration of exhaust is only a partial answer and is unlikely to be sustainable.
Even if all buses were Euro VI standard (very few are in Norwich), their maintenance and daily operation is far from test-bed conditions.
Many vehicles on our streets are over ten years old and have had a hard life. In these circumstances the share of emissions per passenger can be greater than if they each travelled in their own car.
We’ve had a ‘low emissions zone’ in Norwich for over 10 years, but perhaps it’s time to raise the game and tackle the diesel exhaust problem at source.
Are we bold enough to make a local decision to ban diesels altogether and allow only emissions-free vehicles into the city centre?
This is now realistic because of the viability of electric-powered vehicles. Oxford was first in deciding to implement a ‘zero emissions zone’ from 2020, and other cities in the world are following suit.
Such a decision could also be a step change towards getting a modern rail-based transit system that would be quiet and civilised - and at least as clean as those trams of a century ago.
• Matt Williams sits on the Norwich Society strategic planning and transportation committee