Where does Bristol's pollution come from?

20 mph is looking like one of the big manufactured controversy issues of the election. Not, say, library closures, or the sale of the Avonmouth ports and apparent abandonment of Avonmouth. No, 20 mph limits, along with parking restrictions. Who says the electorate isn't worrying about city wide issues?

One of the pro-speeding campaign claims is "20 mph causes pollution".

Bristol has a pollution problem. It has an Air Quality Management Area which covers the centre, and also follows the A38 and M32 out of town. And apparently even the council admits it is killing people.

Where is that pollution coming from? Well, for NOx, the nitrogen oxides which VW tried to cover up, it's coming from Diesel cars. Bristol's NOx problem would be significantly reduced if everyone driving diesel today switched to petrol. Not hybrid or electric: petrol would be a start, especially modern cars that turn off the engine when stopped. And with gearing such that they can cruise at 20 mph nicely.

What is that ratio of petrol:diesel in the city?

We have no data, though the council's ANPR camera arrays will have that information if they could sit down and analyse it. Otherwise, it's that same self-selecting short term surveys which we are always so disparaging of. Here's ours



This was taken by a tax dodger cycling up the shared use pavement on Bridge Valley Road. While most shared use pavements are technically, "bollocks", this one is worth using. The speed of the cyclist (4-6 mph) is at a significant different from that of the motor vehicles, so you will only get passed by everything. The speed limit here is 30 mph, its off the portway and cumberland basin flyover, drivers may not have seen a bicycle that morning and forgotten they exist. And there's almost never anyone walking. If there's a fault: pavement surface quality and sweeping; the usual.

Going up the hill on a bike, you can see the motor vehicles come in waves; a queue heading west from the cumberland basin builds up until there's a right turn light, then they set off. You get a minute or two of quiet, 30s of traffic, then repeated until you reach the top. The video shows one of the groups of cars and vans.

Let's look at engine type, confirming on the MOT checker site whenever the registration number was readable and it wasn't immediately obvious

• white (VW?) van. Diesel
• white van. Diesel
• BMW 330d. Diesel. Passed MoT on Feb 22, 97K miles.
• VW Passat. Only available in EURO-test-rigged diesel models. 100K miles on 16/11/15
• Audi A6. Diesel
• LGV. Diesel
• Ice cream van. Diesel with dodgy fan belt.
• white van. Diesel. 84K miles
• Peugeot 308 Diesel. (Passed MoT on second attempt feb 17; 78K miles)
• Mercedes SLK230K, petrol. 50K miles after 15 years of use.
• Ice cream van. Diesel

11 vehicles; only one petrol engined. That's a ratio of 10:1.

As stated, this is a self-selected dataset, but even so, it didn't involve a cyclist going up and down the hill repeatedly until a group came by that were nearly all diesel. It was just the outlier. If one more petrol car had got through the ratio would have dropped to 5:1, awful, but not as bad.

We don't have any real datasets of the petrol/diesel ratio, and this being an out of rush hour measurement may show bias towards working vehicles over commuters (unless a lot of people go to work on an ice cream van, that is).  But it does point a lot of the blame at our NOx problem at Herr Doctor Diesel and his inventions.

This also means the mercedes owner has something to be smug about, as well as having a vehicle still worth more than the Peugeot or the Passat: every mile they've driven has chucked out a fraction of the pollution of the other vehicles, as well as only doing a quarter as many miles/year as the others. Too bad their wingmirrors cost so much to replace.

Bristol: cycling discriminates against the obese and the unfit

There's a bit of an upset in Birmingham currently, where (conservative) councillor came out and accused cycling of being discriminatory on race and gender, and that the £23 M could be better spent on things like parking spaces. And that it is also biased against women who want to wear modest clothing.

Well, we agree, in Bristol it is a discriminatory form of transport too. But not on race or gender.

No, in Bristol, Cycling discriminates against obese people with no legs and a lifestyle focused on fry-ups rather than hill climbs. These are people who suffer in our city.

Take this scene here, a mature Bristolian rastafarian working his way up Bridge Valley road. He's very much not a young white man -but to get up the hill on a road bike he has to be fit. A large proportion of our population —especially the residents of the suburbs, are significantly overweight, smoke, and generally live an unhealthy lifestyle.

These are the people that our city cycling project discriminates against —and no amount of cash on cycling infrastructure will fix that, unless the infrastructure involves lifts and escalators.

These are also the people that the city's expanding RPZ project discriminates: people to unfit to walk more than 15 metres to their destination. Removing all the free parking penalises those people who are too unfit to walk or cycle anywhere, by forcing them to pay.

The only person who cares for those people's needs is Eric Pickles –because he is the only politician who understands what it is like to obese and unfit. This is why his "short stops on double yellow lines" proposal is targeted at them: now they will be able to stop outside the newsagent to buy a packet of fags, then drive on to the chip shop to buy the evening meal.

Segregated cycling facilities will make this worse by removing short-stay parking opportunities, discriminating against the obese and the unfit merely by their very presence.


Returning to Birmingham, gateway to the M6, the councillor's colleague, Councillor Hutchings came out with the other part of the story, when he said “he feared hoards” of cyclists would have “a severe impact on pedestrians and motorists”. That's the other way a cycling program penalises the obese and the unfit. If you aren't fit enough to cycle round the city, driving is all you can do. The more cyclists there are, the more you get held up.

This is why the very presence of cycling infrastructure and increased cycling is so discriminatory against overweight suburbanites who will be hit by the triple whammy of cycling infrastructure removing main-road short stay options, the RPZ removing back road long stay parking, and finally cyclists themselves being in the way. Oh, and of course there's the 20 mph zone slowing down the journeys from their houses to the chip shops.

This is why it is critical that the Birmingham councillors recognise that cycling doesn't discriminate against gender or ethnic groups —if that city doesn't get the funding then it could come Bristol's way, and things would only get worse!

Finally! Some suffering!

After the shocking scenes of happy cyclists, we managed to position our camera the next day to catch some cyclists looking unhappy about the hills in the city.

First, this one at the top of Marlborough Hill

Later, this one atop Cotham Vale

And here, at the top of Constitution Hill. The sheer expression of suffering is heartwarming it should be the cover photo for the next council-funded cycle-in-Bristol newsletter.

Finally, someone suffering up Bridge Valley Road.

It is good to see these people in pain, makes up for the space and money they cost the city. Odd that whoever they are, none of them have helmets and hi-viz on, just T-shirts and fixed wheel bicycles, but that just makes them suffer more, which is how we -and clearly they- like it.

Bridge Valley Road: stolen

Parking on the Downs for a picnic last week was pretty hard. It wasn't just all the roadside parking spaces were taken up, everywhere off the road where you could get a car was full with a family or two, parked up, cooking up a barbecue. No room for more cars

Except what's this round the corner: Bridge Valley Road. Closed to through motor traffic on account of emergency wall repairs.


We understand the need for this, but resent two things. First, pedestrians and cyclists are allowed up the pavement. Second, the road is fenced off, so preventing the area being used for parking.

If some turnaround zone had been provided at the end, you could have parked cars on both sides of this road, so added room for a few hundred more families on the downs.

They could even have used the footpaths that aren't normally accessible on account of the high speed passing traffic to get up to the park.