VU61HXM : Nissan Driver doing clifton roundabouts "french style" in the snow

We're an organisation which believes in data and experimentation. We have time for experts.


Normally we can't be arsed to send videos of near misses to A&S police on the basis that it seems an exercise in futility. Let's look at the track record of our limited number of attempts

1. Sept 2012, R242AAC. Shoots out a roundabout, nearly hits the parent. Outcome: Five penalty points. Notable that (then) Cllr Jon Rogers was pulled in early —is this the way to get a result?
2. April 2014: Double-overtaking driver of Peugeot L861CDW nearly runs over family. Outcome: A&S Police Sergeant tells off cyclist for swearing when they think their son is about to die.
3. Feb 2016, SWC scaffolds van HK15FYH. Reporting this van driving over a roundabout while texting involved cycling to Chipping Sodbury to hand over a CD with the video and file a report. When followed later that month, nobody had any record of it. Chipping Sodbury Police: "we passed it on". A&S HQ "we have no record". 

It's got worse. We've gone from Prosecute to Won't Prosecute to No Record of Incident. And that with  a trip to Yate added in.

It's 2019, three years since the last experiment. And this one merits it. A Nissan Note nearly being driven into a cyclist because the driver has chosen to drive the wrong side of the mini roundabout, in winter conditions, where the cyclist is forced to swerve into snow and ice to avoid the car driving into the side of them.

Our tax dodger (expendable) is coming into Clifton on Suspension Bridge road, heading towards the more interesting parts of the city. Because all the side roads are iced up, the main roads are the only options, and there, the central lane where enough traffic has melted the snow.

Our cyclist carefully cycles round the roundabout, making a controlled turn through the junction, avoiding snow, avoiding banking into the turn, lining up perfectly to exit in the snow and ice-free part of the road -the only place to be in these conditions.

Except, what's that engine noise coming from the right hand side? It's the Nissan Note VU61HXM, also taking the roundabout, this time on the completely opposite side of the roundel. If they have a driving license, it had better be a French one. And they have to be able to say more than "quoi? je comprende pas? Est-ce-que il-y-a une probleme?" when questioned.



In normal weather conditions, that would be an selfish and dangerous thing to do. In snow conditions, conditions where the police and met office were warning everyone to think before they travel, and take care when they do —it's tantamount to attempted murder.

The cyclist was: positioned on the snow free part of the road, carefully using their (hydraulic disc) brakes, riding with tyres (2.4" Conti Mountain King ) suited to bad weather, and taking corners really, really carefully, both hands gripping the wide bars for maximum control. Oh, and avoiding the side roads which don't get swept or gritted.

The driver "Oh, this cyclist is taking too long, I'll just dive across the road. Oh, they are shouting and waving. I shall carry on without slowing down or changing my line —they shouldn't have come up the inside of me"

When you see a car aiming straight for the side of you, there's no point trying to argue rights of way, it's time to make an emergency turn into the snow -avoiding braking at the saame time as that's guaranteed to lead to a fall. Then, once to side, controlled deceleration.


If there had been any ice underneath, this would have caused a fall, and, with a car twenty centimetres away, guaranteed injury. We wonder what the driver would have said then —aassuming they stopped at all.

Certainly driving off seemed to be their sole reaction to the near-collision



It's interesting to look back. They only come up behind the bike within the last ten seconds of the approach to the junction —the time the cyclist is gently slowing down. And, irony of irony, because the tax-dodging cyclist stopped to let the family cross the zebra crossing. If instead they'd gone straight over the crossing (the kids hadn't stepped out, so it'd have been legal, albeit antisocial), then VU61HXM wouldn't have had a chance to run over the cyclist.

At the junction itself the driver didn't even make any attempt to drive legally. Look at the angle of the front wheel. They were lined up right from the outset to cut across the roundabout and the cyclist.  Not a moment of hesitation, not even to safely assess whether there were any drivers approaching from the right. The decision to drive on the wrong side of the mini roundabout had been made before they started to pull out.


And it's not like they "just" went onto the painted roundel. They barely grazed it with the passenger side wheels.


The rear view also shows how close they come knocking the cyclist off. With the wide angle lens, that is probably within 15 cm.


The only way to put a safe gap in was to put both hands on those MTB bars bars and steer into the snow, while taking care to stay upright.



This is one of the worse bits of driving experienced for a while. In the worst road conditions Bristol has experienced for almost a year.  In terms of actions, it makes the cut for the CPS guidelines for prosecuting dangerous driving.

• failing to have a proper and safe regard for vulnerable road users such as cyclists
• overtaking which could not have been carried out safely;
• disregard of traffic lights and other road signs, which, on an objective analysis, would appear to be deliberate;

And particularly:

• a brief but obvious danger arising from a seriously dangerous manoeuvre. 

Let's see what happens. Filing planned for Saturday, with the full "dull" long video and a detailed statement; will do a followup in the week to make sure the NIP is in the post, then we'll see whether this makes the cut as something worthy of the CPS's time. Oh and this time: ruthlessness from our side. Missing report: escalate. Failure to prosecute: escalate and publicise.

If A&S police don't do better than they have done in the 2014 and 2016 experiments, they may as well cancel their safe passing program and give out Nissan Notes instead.

fraternal greetings between arrogant and self-entitled road users

We've observed before that there's no real difference between cyclists and the owners of fast german cars: Arrogant and Self-entitled wankers: the only variable being how much kinetic energy they bring to a collision.

You can see that some of the individuals are in fact self-aware of this little detail. And rather than treat "the opposing team" as unworthy, instead welcome their presence and greet each other as they pass.

Here we can see exactly this at work, with our tax dodging adult and teenage child heading towards the Clifton "dead zone" from the more exciting parts of the city, on a weekend afternoon where almost nobody is around. This St Pauls Road, incidentally, because its the way from Clifton to those more exciting parts of the city. It continues as "Tyndall's Park Road", because the Bearpit roundabout wasn't considered in the victorian era destination, so "Bearpit Avenue" is eternally denied our city.

You can see, as they head down St Pauls Road, a Porsche turning in from Whiteladies Road, cutting the corner as it revs up to the 20 mph speed limit Marvin Rees is yet to publicly abrogate —though his state of the nation "we can't punish driving" hints that it will come soon.

It comes up behind the two cyclists; the father riding alongside the child to stop both of them getting close-passed.

Rather than get upset, the Porsche driver pauses for a moment, assesses the situation, and recognises a fellow arrogant and self-entitled wanker. They pass, but close enough they can see each other clearly, and sound a friendly on their horn as they pass.

Our cyclist, also recognises a fellow arrogant and self-entitled wanker waves a friendly hello back. After all —why else would someone beep their horn in a quiet Bristol road except to say hello?

20 mph sabotage at Leigh Woods

Our mid-august coverage of the 20 mph "firstbus" review, was illustrated with a photograph of a 20 mph sign nonchalantly keeling over.


That photo was taken on Bridge Road, the approach to the Clifton Suspension Bridge from North Somerset. If you are driving from Portishead down the 40 mph-limited A369, or sprinted down Beggar Bush Lane from Failand (60 mph), this is the first sign you are entering the Big City where you have to temper your expectations of speed with the need to share the road with people on foot and bike and keep your speed at around 20 mph.

Here's the sign today.

More specifically: it's where the sign was. Rather than repair the sign, someone in the "hypothesised" North Somerset Highways Maintenance Department has decided that rather than repair the sign, they'll just take it down and fill in the hole.

Which means, for anyone approaching Clifton on this road, there is no large roundel here warning of the speed change. There's one on the other side of the road, but it can be hidden by parked vehicles.
As a result: no major cues that you are in a 20 zone.

Does it change people's behaviour? Hard to tell.

Here's a rear-view clip from earlier in the week of one of tax-dodgers (expendable) approaching the bridge and going past where the sign used to be. They're doing 20-25 mph in the 30 mph zone.

If you look at the speed of the car WR07YFL coming up behind, it's probably doing 35-40. And, as they both cross where the sign used to be, the driver decides she doesn't want to slow down for a bike only doing 25 mph, and instead swing past. Which, given our tax dodger is positioned in the middle of the lane, and there's a lane separator fast approaching, isn't going to work. She eventually slows down and tucks in behind, only getting an option to go forwards when the cyclist pulls over on the "they don't have to pay any-more!" cyclist bypass of the toll gate. And then, the same cyclist pulls out in front and speeds up to 20 mph again, enough to stop the car from overtaking. We've documented dangerous passing on this bridge before; at least here the driver was sensible enough to not attempt it —but we wonder, if it had been an oncoming bike, not a car, would she have done any differently?

In town, she drives less aggressively; the cyclist is now "only" doing 20 mph, but so are the cars in front. Seemingly having the reason for the speed constraint being a car, not a bike winds up the driver less. Again though, we have to ask: if it hadn't been for that, would she have made another attempt?

Who knows? And one recorded incident doth not a defensible dataset make.

For now: if caught driving above the 20 mph limit, anywhere in the inner zone, just say "I came in over the Suspension Bridge and didn't see any signs!" Which, if it works, shows that all it takes is some laziness from an adjacent council for the whole 20 mph project to slowly fail.

20mph: get your opinions in or lose to FirstBus

Bristol Council has a ongoing consultation on 20 mph limits.


We are happy supporters for the 20 mph limit in Bristol, for various reasons including:

• We live in the city and want one which is good to live in.
• Our children walk and cycle round the city, and we like them to come home alive.
• A defensible study on the 20mph zone concludes that it directly saves lives.
• If you live in the Red Zone, you want the council to do things to get people using cleaner transport options than driving, and this and RPZs, along with more aggressive actions, are needed here.
• In the Important Car for Important People, driving at 20mph is no harder than driving at 30 mph; fuel consumption (in a vehicle which turns off its engine at lights and in traffic jams), the same. 

Now, regarding the consultation, there's a large list of roads where raising the limit is being considered. 

This proposal is fundamentally wrong.

1. The roads they propose are the roads people cycle on. 
2. They are the roads children walk to school on.
3. They are the roads which anyone walking round the city has to walk on and/or cross.
4. Some of them actually have schools on.
5. Many of them are shopping streets, where encouraging people to visit and walk to shops, even across the road, is much more important than a nominal peak speed of 30 mph.

Everyone who lives in that inner city, and wants their streets to be more than rat-runs for the suburban visitors, should get their opinion in, support the proposals as is *and argue against changing the limit on any road in the zone.

Changing the limits will massively increase the costs, as now every 20mph-30mph turnoff/junction will need speed-limit-changed signs (go to portsmouth to see this). And at peak hours it will do nothing for journey times.

Why then the proposal? And why the choice of roads? Presumably Marvin Rees & team are trying to keep some groups of people happy. But whom? Well, one little reference is to "stakeholders". And what do the majority of those listed roads appear to have in common? FirstBus buses run on them.

Has FirstBus just given the mayor a list of roads in the 20mph zone where their buses go round and said to him "if you make these 30 mph all our scheduling problems will go away, FirstBus will be wonderful and Metrobus a success?" Because if they did, it's a lie

Looking at that list of roads, comparing it to a bus map, and its hard to conclude that the names aren't from firstbus, and are driven more by their belief it will help scheduling than any concerns about the safety and wellbeing of the inhabitants of Bristol's 20 mph zones.

If you don't want FirstBus to be setting speed limits in Bristol, make your opinions known ASAP.

Photo: the 30mph/20mph boundary on Bridge Road approaching the suspension bridge from As, someone clearly didn't see the speed limit sign and decided to go straight into it. That road isn't on the review list, while nearby roads (Pembroke Road, Clifton Down) are. But then, FirstBus buses aren't allowed over the bridge, are they?

Friday Quiz: turning or parking?

Is this car GK06AUN, pictured one morning in Clifton

(1) turning on the wrong side of the road

(2) parked?

The correct answer is: it makes no difference. Oncoming traffic has to assume they are are turning vehicle, so slow down for a junction in a way that the painted give-way signs would never achieve.

This shows how Bristol's drivers do think of the safety of others, not just when driving, but when parking.

(this was published in 2009; updating the tags has had it relabelled as new. There's probably some yellow lines here now, forever deriving somebody important from parking on the closest corner to their home)

fuckwit RLJ at race speed

People ask us: why no coverage of RLJ-ing cyclists? Well, we generally leave that to grumpy Havana Coffe Hamid, on account of his soundtrack choices and spelling skills. But when the opportunity arises, well, we do

Today then, this fuckwit


This is filmed from St Pauls Road, leading from the dull part of town, Clifton, to the more interesting bits, albeit after a final bit of climbing and a university area inevitably full of texting students.

Approaching the lights, they're red, time to hang around for a while waiting for green. And then slowly off, in case the BMW driver is in an hurry. No problems there, except carving out from the left is someone on a road bike, looking like they are near that 20 mph limit, blowing straight through the red light to make a high speed turn into St Pauls Road.



On the shout of "fuckwit" you can see some surprise and a bit of a wobble, though delayed. Leaning into the corner like that, he was fully committed to the bend: the only two options were: carry on or come off sliding sideways exploring the concept "road rash" more fully. It'd have been interesting to see if a scream of "no brakes" would make him choose the latter,

What were the risks this fuckwit exposed themselves to?

• If the car he had cut up on the inside had gone through the light themselves: crash
• If the BMW turning right from Tyndall's Park Road had been in a hurry: crash
• If a vehicle coming out of St Pauls road had been in a hurry, he'd have cycled into it.

And of course, if our tax-dodging reporter hadn't been so slow setting off: they'd have been in the crash too. Which is why we think this fuckwit deserves coverage.

Bristol: Snow Day == Smug Day

It was pretty chaotic night out there. On the one hand: almost no traffic. On the other, an Audi A3  trying to get up a slight gradient and stuck wheelspinning. After about 15 minutes people start looking out the window thinking "maybe should help", after another five minutes they open their doors, get out and start pushing. Who says there is no camaraderie between passengers in Audi and the driver?

As the residents are all staring out the window "will they fucking get a move on", the passengers help turn the car round so its weights on the front axle, and it manages to get another 15 metres up the hill before being abandoned. Hopefully BCC have suspended overflights of RPZ enforcement drones for the next few days.

One of the wierdest things was the fact that everyone was driving well below the 20 mph limit. This completely throws off your decision making as you think "I'll wait until they get past before pulling out", and yet they take so long you think "I'll just pull out in front of them". It's the Audi/BMW driving experience on a push-bike.


All mini-roundabouts, give way signs and zebra crossings are suspended, and you can stop in the middle of the road to talk to people. Not different from normal, except now you have a better excuse when challenged than "fuck off"

We considered setting out to a nearby pub on the off-chance of getting snowed in and trapped for 2-3 days. But which one?

1. Duke of York: good pub, risk of being stuck with David Wilcox. Which is fine, except after 24h of cider drinking he becomes a barge evangelist. We don't care for barges and think the remaining waterways of the city would be best built over the way they did with the River Frome to give us the M32. Sooner they do this for the harbour, the better. In fact, we are surprised the WoEP haven't suggested that to Marvin, as it'll be more popular and easier to deliver than a metro.
2. Miners Arms: Thursday is Pub Night. Risk of a three day lock-in with pub quiz enthusiasts keeping on with the quizzes as something to do. Challenge of explaining to A&S Police how aforementioned pub quiz enthusiasts all ended up being killed messily with the kind of small nail clippers airport security love to confiscate.
3. Farm Pub: highest chance of becoming stranded, Doom Bar on draft, easiest to acquire locally curated ganja (we are told). 

Tough choice

Anyway, that was friday, what about today?

Rejoice! Today is a day is a great to be smug!

Because yes, those of us who have the equipment to get round can go round, offering smug advice to everyone trapped.

Drivers of 4x4s and SUVs

Landrover Defender drivers have it easy today: that rickety thing they've kept alive through trading bits on ebay can now be used to cruise round the city. Wearing wooly hats, fingerless gloves and warm clothes obviously, given that class of vehicles' heating system.

Urban SUV drivers have a similar option, but need to be careful. Today may be the day that you can finally justifying spending £15K on top of a practical car..

Do: drive round, nodding knowingly at other SUV drivers.

Don't: discover when you get to a hill that you only paid a £12K premium and so have the 2WD model.

Do: use engine braking on the descents. If your car is an automatic, time to work out how to put it into manual mode, or try the cruise control.

Don't: discover while driving down one of the steep hills in Totterdown or Cliftonwood that it doesn't make a difference between 2WD and 4WD when it comes to using the brakes. No winter tyres, sliding into parked cars screaming.

Owners of cars parked on hills

It's too late to move them unless you pay your neighbour with a landrover to tow them somewhere.

Do: sit by the window, looking at your car, camera in hand, ready to jump out and take pics of whichever 2WD SUV drives into the side.

Don't: own a car of any net value.

Mountain Bikers: 

Do: cycle round offering smug advice to people trying to drive up and down hills.

Don't: get off and help, admit that it doesn't work and then, while pedalling of shamefully, wipe out on a patch of ice.

Pedestrians:

Do: walk down the middle of the road. Its the only bit which will get gritted after all.

Don't: look at your phone while walking round. Not today.

Don't: walk round with your hands in your pockets, in case you need to put them down when you slide out.



Skiers
Do: get out the skis you've kept under the bed for a decade, carry them to some hill and ski down.
Don't: go on about it for years in any of the pubs our team members frequent We don't care, really.

Mid-life crisis mountaineers

We want to have a special call-out to mid-life-crisis mountaineers, the ones you see out in Gloucester Road or Southville of a weekend, wearing a down jacket branded with North Face, Patagonia or Mountain Equipment,

This is your chance to get out all the stuff you've bought from Taunton Leisure of Bedminster over the years and stomp round the city

Do: get out the most excessive bits of equipment you have in an arms race with all the other mid-life crisis mountaineers.

Do: walk around being smug, especially on the deepest snow parts of the pavement, rather than the middle of the road where it's clear.

Do: remember that if you wear crampons, walk with  your legs wide apart so you don't step on your own toes.

Do: talk to random strangers, casually dropping phrases like "hut-to-hut through the Haute Savoie Alps" and "New Zealand South Island trekking", or even better, "Everest Base Camp"

Don't: get out your stuff to discover that since you last went near any of those places the plastic boots have gone brittle and failed.

Us?

Well, with an equipment failure like that, its trapped in the Farm Pub. We just wish that skier would STFU or we'll have to start looking for those nail clippers

Fixie Riders: don't Slipstream Mountain Bikes

It's January, and you can see who is out and about on their new fixie bike. This rear view video show our (expendable, tax-dodging) reporter turning off St Pauls Road, Clifton, onto Pembroke Road,
at a double-mini-roundabout put in to break Satnav. And coming up from the triangle, along Queen's Road, here comes someone in a shiny clean fixie, who decides to slipstream our reporter (expendable, tax-dodging).



This is where they a number of mistakes

1. Cycling behind someone on a bike without letting them know you are there. Risk: the rider in front might perform some manoeuvre without warning.
2. Cycling directly behind the bike, rather than off to one side, generally further from the pavement. Risk: you have to be able to stop as fast as the bike in front.
3. Cycling behind a mountain bike while you have a fixed wheel bike,
   albeit with a front brake.

We'll assume they were a bit drubbed from the climb and so didn't feel like passing, but they should have hung off to one side. At the very least, when they got behind our reporter (tax-dodging, expendable) they should have looked at the bike, and realised that it was a mountain bike.

In the video, you can see that the fixie rider (tax dodging, expendable, not so good at braking fast), gets to cycle behind the mountain bike until 00:30, when, in front of our reporter, someone on a phone steps out onto the zebra crossing. This puts our reporter into an aggressive-but-non-emergency brake. All well, until someone one a bike shoots up their left, almost into the aforementioned pedestrian. Which was a bit of a surprise.

It was only later, when the question "where did that rider come from", went through our reporters idle mind, that they went for the rear camera and had a look to see what happened. As you can see, they had their hands on the bars, drifted in right behind our camera, and, when the bike in front has to do that stop, nearly ride straight into the back of them, only avoiding it by swerving to the side.

Mountain bikers don't do chain gangs. They don't go along taking turns at the front, slipstreaming each other for performance, before hanging at the back to cycle no handed while you rummage in your back pocket for a gel with the same texture and flavour as baby food. Nor do they try and communicate with each other with little twitches of the hand, or pointing down and waving to say "there's something on the tarmac to avoid".

Instead they cycle along with enough of a gap between the rider in front so that they can see, enjoy and then learn from the mistakes the rider in front makes, rather than join in the crash. Food? Maybe, but they'll stop for that as they are generally lazy and view "cycling no hands" is one of the precursors to a trip to A&E. As for pointing out gravel, potholes or other surface hazards, those are not things to swerve around, they are there to jump over.

And, unlike fixie bikes with one front caliper brake, a modern MTB has hydraulic disk brakes, which, if the bubbles have been squeezed out of the cables, lets the rider bring the bike sliding to a halt with only the light touch of one finger on the brakes.

Because of that one-finger braking, mountain bikers are generally split into the "index finger faction": cycle with their index fingers on the brakes and the "middle finger faction", who use their middle finger. Whatever the choice, except on uphills, they're going to be cycling with their chosen finger on the brakes at all times. And when needed, they'll know to put that on, push their butt backwards to keep maximum weight on that rear wheel, with its 2.2+ inch surface on the ground, and so rather than skid, bring their bike to a halt faster than you could stop a British Leyland era Austin Mini (*).

When you come up behind a bike, see that its got wide tyres and disk brakes on the back, instead of cycling close enough to see whether the brakes are Shimano, SRAM or Hope, you need to think "this is a bike which can stop fast ridden by someone who may know how to use them", and not cycle right up their arse without even saying hello.



Do you know this rider? Are you that rider? Whoever it is: either hang off the side or stay back, especially to mountain bikes. Thanks

(*) MkI Minis had non-servo assisted drum brakes and to stop rear-wheel skid depended on that battery in the boot along with the WD-40, the hammer and the tow rope. As a safety feature, it was designed not to go very fast.

Volvo bug reports, issue #1: MGIF driver

Given some of the Volvo self driving car developers are ex colleagues of Bristol Traffic team members, we get to file bug reports. Not some directly accessible issue tracker where you get to file stuff like "XC90 driver nearly killed me" only for tech support to close as a "works as intended", but at least get to give them cues about how their land-barges get used and abused in the field. Here's one of this week's Volvos. Mid-afternoon, not rush hour but within range of school pickup times. Sunny days to treasure before the miserable season settles in.

First: "MGIF" , "Must Get In Front"

Definition: A driver who is focused on overtaking the bike without looking ahead to consider "What happens next?

In AI terminology a "planning horizon of 1", usually loses to any computerised chess/draughts player with a horizon >= 2 unless the latter is awful about assessing the value of all enumerated moves & countermoves.

In this instance,

1. the speed limit of the bridge and the rest of the city for the subsequent 1-2+ miles in any direction is 20 mph. You can see one of the signs at 0:01 in the video
2. the cyclist she chooses to pass is doing 19-20 mph, still accelerating in their underresponsive steel-framed MTB.
3. The car a safe stopping distance in front is also doing 20 mph
4. And it'll have to slow down once it gets to the end of the bridge due to the road there (i.e it's 100% predictable, irrespective of time of day & pedestrian/traffic numbers)
5. the oncoming cyclist is going 15 + mph

Which means that

(a) there's no defensible reason to pass the cyclist "I need to break the law to overtake a bike cycling at the speed limit to get behind the other vehicle going at the same speed before I get into the city proper and really have to slow down".

(b) she's failed to anticipate how long it will take to overtake the bike, even as she speeds up to 25-30.

(c) the closure rate with the oncoming cyclist becomes about 40-45 mph. If the oncoming roadie hadn't been keeping to the far left of the lane, there'd have been a collision.

Looking back at the footage, she's hanging back at the split to two lanes at the tolls to make a late-binding choice of which one to go through -a slight sign of impatience.  She takes the left one; the right hand one is occupied by an SUV whose driver can barely see over the wheel, which is why the cyclist chose to hang back and wait: didn't seem safe to go ahead. As the Volvo comes through fairly rapidly, it's probable she has one of the contactless cards which you top up with prepaid bridge crossing tokens; sign of a regular user. Given time of day, perhaps a resident of N. Somerset doing a late pickup of a child from somewhere in Clifton, someone who cannot afford to be held up by any vehicle doing the speed limit.

Now, what is he dev team planning w.r.t. oncoming collision avoidance, where it assesses oncoming velocity of the approaching vehicle, adds with its own and estimates time-to-impact, so perhaps suggesting some alternate actions? And what to suggest? There's the "massively accelerate, swing in hard and then brake" strategy, which is an extension of this drivers decision (and essentially a reward), the alternative is: brake, swing behind the cyclist they tried to pass, put it off. Which is safer, but not generally that common amongst "legacy" manual-drivers. There's some psychological "we're committed now" decision which interferes with the more rational "braking to survive is a good idea" strategy.

enjoy

P.S. UK DVLA now gives MOT history over time: https://www.check-mot.service.gov.uk ...you can see that GP05RZE used to be a 3K/y child seat equipped barge of Hendon, NW London, then over to bristol to do 15K/y. Where you can see from the repeated warnings "pitted/scored disks, front headlamp deterioration" that the owner doesn't actually do any maintenance. Probably not a good sign. Almost as bad as a MkI Golf GTi with the wheels coming off..

Proposed: tax vehicles based on their width

A quick trip through the capital of 4x4s that never see mud in our city, Clifton, makes it clear that even here we don't have space for such fat vehicles. Even the parked ones like that silver mercedes is wider than the parking bay -and that's with the bonus wide Clifton bays.



It really becomes clear following the BMW X5 across the suspension bridge. The thing is simply too wide. Why is it so fat? It's to compensate for the fact that it's centre of gravity is too high on account of the raised suspension: this is a land-barge which would topple over on bends otherwise, as Ford Explorers turned out to do. The X5 is so fat that when it meets and oncoming Landrover Discovery, they have to slow down to negotiate passing each other.

In other bits of the city, in everyday cars, drivers would go past each other without even looking up from their
phones. Yet all it takes is one or two selfish drivers thinking "hey! an SUV would be cool!" and our city is brought to its knees.

Hence our proposal: make the VED of a vehicle proportional to its weight and width. The weight: the maintenance cost of our roads. The width: how much they inconvenience everyone else.

Without this, there will be no way to stop this plague of overweight barges on our roads.

Clifton Occupied by Tax Dodging Cyclists!

We were shocked and disappointed that we were unable to drive to Clifton in our Important Car, then cross over to Somerset and enjoy a round of golf with Liam Fox MP. Why? Tax dodging cyclists in the road —out road, blocked off to us,Important Tax Paying people, handing it over to olympic medal winners and the like.

Lycra louts who do things like blow their noses in public

If there was one redeeming feature, it is that a lot of other people were as upset as we were to see this lycra-clad vermin —and they were standing there screaming at them for bringing the city to its knees.


We we trapped in the city. Clifton was even begrimed with a large screen showing off that the portway and Bridge Valley Road had again been stolen.



This is exactly the kind of thing people voted against George Ferguson wanted to stop, but still the city wants to let people cycle around.

It's fundamentally wrong. Look at this scene from The Promenade

Where are the revenue-bringing shoppers? Or the high-income tax band residents? Nowhere. Just one person on a bicycle who probably lives in a postcode other than BS8.

This is unacceptable!

If there is one redeeming feature, it is that Clifton Village is still not set up for more than six bicycles at any time, as their three sheffield racks were overloaded. Some of the tax dodgers even went as far as leaning their bikes against the wall of The Mall pub and trying to buy beer inside.



This is not some run-down bicycle friendly part of town where you can lean bicycles against walls; it is trying to stay upmarket. Fortunately, most of the cyclists in the area realised they were unwelcome and cycled off to other parts of the city once the event was over, leaving us nearly the only people walking round an near-empty village. The fact that village was so empty shows precisely why such cycling events must be prevented.

But how to do this? We were going to spin up our automated cyclist-hating letter generator and have it email the Bristol Post. But what did we see on the Downs?



Yes —shocking, isn't it! Our paper, the one that hates cyclists, actively trying to sell copies to cyclists!

We fear that the Evening Post has, purely in the mercenary need to sell to people under the age of sixty, has decided to start trying to ingratiating themselves with tax dodgers. They may think that will help them, but all it will do is alienate their current readership. It'll be like when all the pubs in Hotwells, including the Spring Gardens, the Pump House and the Mardyke suddenly decided they wanted to post gastropubs instead of places to get drunk in and start fights with strangers. This isn't progress: this is a sign of the decline of the city.

Gateway to Clifton: The Christchurch Mini-roundabout

Today we celebrate the Bristol School run week, now combined with the FirstBus failure week, with very unexciting documentary of the "not quite a roundabout" junction at the end of Suspension Bridge Road. If you are expecting to see anyone nearly being run over, people on phones, etc. Look elsewhere. Sorry. This video is here just to look at what transport issues Clifton has which the Clifton BID and resident groups never seem to cover.

Clifton likes to be known for its village, its Bridge and one or two of its pubs. The real Gateway to Clifton is something never discussed: a mini roundabout at the top of the village, just by the church.

To get an overview without going to Clifton, look at it in streetview and rehearse approaching the roundabout doing a right turn in a car from every road. Work out: when you should give way, when are you technically "in the roundabout and so should expect others to give way", and "is it actually possible to do all the turns legally". The answers being "no idea", "don't expect anyone to give way" and "no".

If you are cycling over the bridge, or driving near it, you have to negotiate it. It's disconcerting on a bike, especially with a child, as you cannot predict what anyone can do. It's a collection of random actions, vehicles coming in at speed, nobody knowing who to give way to —or even what side of the roundlet(*) to drive on. It's not great on a car either. There may actually be some protocol for the locals, but if so they it isn't widely known. We don't know it, certainly. What the locals and regulars do know is not to expect anyone to treat it as a roundabout —and never assume that you have the right of way.

You can see all of this in this unedited 9 minute view of the junction. Keep an eye out for the black Range Rover coming out from the left, and count how many times it does it.



This junction is fundamentally the wrong shape for a roundabout, it has two left turns, one hard, one soft, with the hard one's give way markings about 90 degrees to the roundabout itself. No visibility for anything coming off Suspension Bridge as to what vehicles coming from their right are doing —vehicles which don't often slow down, and hence won't see any cars coming from the left until they pull out. Two manoeuvres can only be executed by driving completely on the wrong side of the mini roundabout. There's one car coming the wrong up the one way street, though it does execute the junction safely. Lots of vehicles going through without pausing, including one of the cyclists coming off Clifton Down. And a couple of times cars on the roundabout have to give way to vehicles pulling on in front of them. Note the lack of tension though —regulars are forgiving of what
happens in a junction of such ambiguity.

Meanwhile that Range Rover coming off the left hand side does it five times in a row: our reporter got bored and went off while they were still doing it.

Before the video recording started the RR driver had stopped in the middle of a zebra crossing to let someone out —presumably they were now waiting for that person to return. But why were they driving round in circles given that with the RPZ roll out there's enough free parking, parking they'd have driven by? Unless they enjoy driving in circles and don't pay for diesel, the only other possibility is they had/planned to use up the 30 minute free park elsewhere. But why not just pull over with your hazard lights on? This is just a sign that some Clifton residents really are different from the rest of the city. The rest of us have mobile phones to co-ordinate dropoff and pickup operations, and to offer something more interesting to do while waiting than making right turns at this mini roundabout.

Finally: consider what it is like to try and cross this junction on foot. While it's not near the centre of the village, at the end of Manila Road (where the BMW drives out from the wrong direction of a one-way street), there's a primary school, some other ones nearby. And at the end of Suspension Bridge road is of course, the Bristol Suspension Bridge —one of the key tourist attractions in a city after Stokes Croft and the M4/M5 motorway interchange. As part of "beautiful suburb of Bristol, tucked away from the hubbub of city life and located just a five-minute drive away from the centre." we'd expect more. Maybe the shops sell postcards of it or something.

(*), Yes, Roundlet is a real word.

Gateway to Clifton: The Christchurch Mini-roundabout

Today we celebrate the Bristol School run week, now combined with the FirstBus failure week, with very unexciting documentary of the "not quite a roundabout" junction at the end of Suspension Bridge Road. If you are expecting to see anyone nearly being run over, people on phones, etc. Look elsewhere. Sorry. This video is here just to look at what transport issues Clifton has which the Clifton BID and resident groups never seem to cover.

Clifton likes to be known for its village, its Bridge and one or two of its pubs. The real Gateway to Clifton is something never discussed: a mini roundabout at the top of the village, just by the church.

To get an overview without going to Clifton, look at it in streetview and rehearse approaching the roundabout doing a right turn in a car from every road. Work out: when you should give way, when are you technically "in the roundabout and so should expect others to give way", and "is it actually possible to do all the turns legally". The answers being "no idea", "don't expect anyone to give way" and "no".

If you are cycling over the bridge, or driving near it, you have to negotiate it. It's disconcerting on a bike, especially with a child, as you cannot predict what anyone can do. It's a collection of random actions, vehicles coming in at speed, nobody knowing who to give way to —or even what side of the roundlet(*) to drive on. It's not great on a car either. There may actually be some protocol for the locals, but if so they it isn't widely known. We don't know it, certainly. What the locals and regulars do know is not to expect anyone to treat it as a roundabout —and never assume that you have the right of way.

You can see all of this in this unedited 9 minute view of the junction. Keep an eye out for the black Range Rover coming out from the left, and count how many times it does it.



This junction is fundamentally the wrong shape for a roundabout, it has two left turns, one hard, one soft, with the hard one's give way markings about 90 degrees to the roundabout itself. No visibility for anything coming off Suspension Bridge as to what vehicles coming from their right are doing —vehicles which don't often slow down, and hence won't see any cars coming from the left until they pull out. Two manoeuvres can only be executed by driving completely on the wrong side of the mini roundabout. There's one car coming the wrong up the one way street, though it does execute the junction safely. Lots of vehicles going through without pausing, including one of the cyclists coming off Clifton Down. And a couple of times cars on the roundabout have to give way to vehicles pulling on in front of them. Note the lack of tension though —regulars are forgiving of what
happens in a junction of such ambiguity.

Meanwhile that Range Rover coming off the left hand side does it five times in a row: our reporter got bored and went off while they were still doing it.

Before the video recording started the RR driver had stopped in the middle of a zebra crossing to let someone out —presumably they were now waiting for that person to return. But why were they driving round in circles given that with the RPZ roll out there's enough free parking, parking they'd have driven by? Unless they enjoy driving in circles and don't pay for diesel, the only other possibility is they had/planned to use up the 30 minute free park elsewhere. But why not just pull over with your hazard lights on? This is just a sign that some Clifton residents really are different from the rest of the city. The rest of us have mobile phones to co-ordinate dropoff and pickup operations, and to offer something more interesting to do while waiting than making right turns at this mini roundabout.

Finally: consider what it is like to try and cross this junction on foot. While it's not near the centre of the village, at the end of Manila Road (where the BMW drives out from the wrong direction of a one-way street), there's a primary school, some other ones nearby. And at the end of Suspension Bridge road is of course, the Bristol Suspension Bridge —one of the key tourist attractions in a city after Stokes Croft and the M4/M5 motorway interchange. As part of "beautiful suburb of Bristol, tucked away from the hubbub of city life and located just a five-minute drive away from the centre." we'd expect more. Maybe the shops sell postcards of it or something.

(*), Yes, Roundlet is a real word.

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.

The Zone map that Clifton Tank Command Dare Not Show

Of all the maps that appear in the RPZ tank-battles, this is one that does not surface.



Its the map of where the air pollution levels in Bristol exceed the levels that are considered safe.

Look at that map. What stands out (to any resident of the city)

1. The entire city centre is an Air Quality Management Area. 
2. Clifton manages to dodge it, primarily by being above the town -though as it gets into Kingsdown and Windmill hill, height is not enough for the roads to stay breathable.
3. The roads into and out of the city are pollution hotspots. That includes Gloucester Road, Bristol's "most popular" cycle road.
4. The Frome valley pollution zone tracks the M32 perfectly.

We can't split the pollution into resident, business, public transport and commuter, apart from the Rupert Street bus & taxi only road —the one with the worst pollution in the city. Usually.

What we do know from the queues of cars on the A370 and A4 Portway every morning is the number of people who drive in to the city.  Any morning you can walk onto the Suspension Bridge and look down at the queue of cars who have done the portishead-M5-A4 route (and from other places, including Clevedon & Weston) and are now stuck in the Avon Gorge, fuming at the empty lane next to them along which park and ride buses whizz past. Any morning you can go to the footbridge above the M32 and look down at the line of near-stationary cars, all sitting with their engines on.

And in any inner-city area that is not an RPZ, you can watch the cars go round and round in circles looking for somewhere to park.

And now what -we have a  Somerset MP actually surfacing in the county to complain that Bristol's RPZ has had knock-on effects for Leigh Woods. Well, that's unfortunate —but not a reason for Bristol to attempt to do something about their air-quality. And an RPZ, if it actually helps alternate transport options in the area -including N. Somerset- will.

What's not covered here is that Leigh Woods has always experienced commuter parking -which was getting worse with the cost of crossing the Suspension Bridge, even before the RPZ went live. People who lived in the hinterlands weren't prepared to pay £2/day to drive over, and leigh woods became the cutoff point.

Well, Leigh Woods is free to roll out an RPZ too. As is Long Ashton. We can't say "but the roll-on effects" should stop any attempt at trying to make the city better to live and breathe in.

As for the residents of Portishead who say that Bristol is now trying to control where they work? 

Sorry. We are trying to control how people get to to work, to adopt options that aren't so literally poisonous to the city.

And the people who say "hold off until there's a viable alternative?" The residents of Portishead were all happy when the council spent £3M widening a roundabout, to reduce the time they spent queuing to get onto the M5 and then to work in Bristol or the North Fringe. £3M for what: one roundabout? Which, in a manner obvious to those of us who actually understand Queue Theory (it's not rocket science, you know), does nothing except move the traffic jams slightly closer to the city. North Somerset, under the guidance of Elf-King App Rees have spectacularly failed to get the Portishead Railway reopened for passenger traffic. They've actively opposed cycle facilities along their roads,  and actively campaigned against cycle routes through their two-cars-per-household-mock-villages.

It is the repeated choices and actions of the residents of North Somerset that have failed to provide that viable alternative to driving.  Why should Bristol care about those decisions? By leaving the city, these people abdicated their right to influence the decisions the city makes. And, in the hands of their democratically elected council, held back any form of progress. When they do attempt something, it fails so badly it gets ridiculed on national TV.

North Somerset are the hinterland of Bristol, not just geographically, but culturally.

Which is why we in the city can't afford to be held back by them.

We aren't trying to tell them where to work. We aren't even telling them how to commute.

What we are doing is saying "The road space and air quality in Bristol is too precious to waste on free commuter parking." By taking that away, anyone who wants to drive in still can —except they now get to pay for that right, so making the external costs of commuting in what is usually a single-occupancy vehicle tangible. In doing so it makes the now-internalized cost of driving in closer to that of using public transport, including the Avonmouth P&R site. It may even provide motivation for the residents of Portishead to push their councillors to get their thumbs out their arses and start working on this —maybe even setting up a Metropolitan Transport Authority covering the CUBA district, so actually giving them some input on Bristol's traffic plans. And, given there's an election coming up, maybe talk to their candiate MPs and say "will you do something for transport in the area other than staged photos in Leigh Woods?"

What we can't do is stop the RPZs and say "business as usual". Because its not just that everyone driving is causing congestion, they are helping poison the city.

Next time someone talks about resident parking zones, say "what about the air quality zones?". And if they don't have an answer, instead complaining how they have to use P&R instead of queueing to get into the city —you don't have to feel sorry for them at all.

Tribars: not for urban use

Following on from our coverage of the fact that its sporty cars that lose from the 20 mph zone, we should look at the impact of the figures on bicycles.

Before anyone points out that bicycles are exempt from the limit, consider that if it becomes a speed that people expect, then going above it would create problems for people assuming you are heading more slowly. Though as any tax-dodger will point out, most people passing your or pulling out assume you are near-stationary and plan their manoeuvre  accordingly.

Even so, fast bikes don't have a place in the city. Stick to 20 or less: and if you can do that on the uphills you've earned those numbers.

What it does mean is that just like fast cars, tribars aren't needed in the city, nor are carbon wheels or polka-dot socks.

Yet here we see someone doing 6-8 mph in exactly that setup.

And while it's nice to see that they are staying way below that 20 mph limit, they do have their arms on the tribars. Which is another way of saying "their hands are a long way from the brakes".

As they reach the end of Kensington Place, they approach the give way point at Lansdown Road, where this lack of braking ability almost catches up with them. Because there's a Range-Rover heading north from Lansdown Place —below that 20 mph— and the cyclist needs to make a bit of an emergency swerve from going into it. Which could have damaged the paintwork on the car as well as written off some carbon wheels.

Bikesnob is always taking the piss of triathletes. It doesn't really apply here, but it does send a message to all: plan ahead, keep your hands near the brakes especially as you approach junctions where you are expected to give way.

Note the yellow lines on the road. This is the Clifton Village RPZ, as you can see on a weekday it is now a wasteland.

An introduction to surveys

Richard Payne of ITV has asked by way of our strategic code-sharing and data mining partners, Twitter, how to explain bias and self-selection in surveys.

This is a topic dear to our hearts for a number of reasons:

1. We consider ourselves to Bristol's premier data-driven traffic analysis site.
2. We recently conducted a survey on traffic issues for the city —a survey which has been completely ignored by the evening post, the BBC and ITV.
3. We have just received an SERC grant for a new project to measure the weight of the city using a stopwatch and a trampoline —and plan to conduct our survey at the BRI next week.

Population: A collection "set" of things you want to measure values from.  Examples: the population of Bristol or all the residents of an area within Bristol.

Subset: Some or all entities within a subset. Example, some of the population of Bristol or some of the residents of an area within Bristol.

Proper subset: A subset of a set which is actually smaller than the original set. (fancy mathematical word: Cardinality). Examples: some but not all of the population of Bristol, or some but not all of the residents of an area within Bristol.

What is important here is that, by definition, a subset of a population must not contain any members outside that population. As examples, a subset of the population of Bristol must exclude people from North Somerset. Similarly, a subset of the residents of an area within Bristol must not contain anyone who does not live within that area.

In our survey we actually measured the origin of our self-selected sample to assess this. We could have just ignored them, but instead chose to include them in our answers on the basis that it was easier just to leave them in.

Data: Numbers. May be analysed by somebody with a statistical background to reach some meaningful conclusions. Without those mathematical skills you'll end up with something as useful as having a rabbit do your tax return.

Measurement: Using some form of scientific mechanism to come up with data about the things you measure. Examples: determining the weight of someone with a weighing scale. Determining the parking and driving habits of people by recording where they park or tracking where they drive.

Invalid Measurement: trying measure something by using the wrong tools, badly calibrated tools or reading the numbers off wrong. Example: determining the weight of people by having people jump onto a trampoline and using a stopwatch to time how long it takes for them to stop bouncing.

Poll: Asking people for their opinions. This is different from a survey in that it is assessing the beliefs of those people, rather than through measurement. Example: asking someone how much they think they weigh rather than putting them on a weighing scale. Asking people about parking and driving rather than actually recording or tracking them.

Leading questions. A sequence of questions which may, unintentionally or not, change the answers to follow-on questions. As example of leading questions, imagine the following sequence

1. Are you aware that being overweight can lead to an increase in coronary heart disease and diabetes?
2. Do you believe that overweight people should be billed by the NHS for medical care for weight-related conditions.
3. Are you a fat bastard?

After the first two questions, nobody will say yes to question 3.

Census: Measuring or polling a Population. Examples: people whose weight you want to measure, or the residents of an area whose opinion on parking you want to known. A census of a population is the only way to come up with a value of the measurement or poll which can be considered 100% accurate in terms of sample set. Everything else is incomplete and therefore inaccurate to some degree.

Survey: Measuring or polling a proper subset of a population —with the goal being to extrapolate the results to the entire population. Examples: weighing only some of the people in Bristol to extrapolate the weight of everyone in the city, or polling some of the residents in part of the city to extrapolate to the opinions of all the residents of that area.

Sample: The proper subset of a population used in a survey. Examples: some but not all of the population of Bristol, or some but not all of the residents of an area within Bristol. Another term is Sample Set.

Defensible: Something which you can present to people who understand statistics without being laughed at.

Invalid Sample Set: A sample for a survey which cannot be used to extrapolate to the entire population. Examples:

1. Including people from North Somerset in a survey to determine the average weight of the population of Bristol.
2. Weighing only those Bristolians who have been referred to the BRI heart clinic in a survey to determine the average weight of the population of Bristol and using a trampoline and a stopwatch to do so.
3. Using too small a survey set for the size of the total population. Example, weighing two people and attempting to reach a conclusion about the weight of the entire population of the city.
4. Attempting to conduct an opinion poll of residents of part of the city without excluding non-residents of that region.
5. Attempting to conduct an opinion poll of residents of the city within, say, residents parking zone, yet deliberately choosing to exclude parts of the area —such as, say, Kingsdown and the city centre.
6. Excluding some of the population on the basis that they do not meet some criteria. Example: excluding anyone who doesn't own a car from any opinion poll on the topic of residents parking.
7. Conducting an opinion poll of the residents of part of the city by only asking those people who have opinions on one specific outcome of the survey. Example: asking only people opposed to residents parking of their opinion on the topic. Conducting a survey by requiring participants to perform some action such as posting in their survey. The latter tends to something called self-selecting samples.

In our survey 32% of respondees declared they couldn't afford a car. These people don't have valid opinions on parking, nor on other parts of our own survey.

Statistical Outliers

These are a fun thing in experiments. Something way out of the expected. You can include these in your answer, though you can also try and work out how the outliers got in there and then discount them —this is especially useful if you are trying to make sure the survey reaches the conclusions you want it to.

Look at our question on the number of wing-mirrors replaced since the 20 mph rollout.

70% of the respondees claimed that they hadn't replaced any wingmirrors since the 20 mph zone. This was utterly unexpected, and, if used when trying to determine the average number of wingmirrors lost per resident per year, we get an arithmetic mean of 0.87 mirrors/year -less than one!

Yet can be explained if we include two other facts from our survey

• the number of respondees who asserted that they lived outside the city: 54%
• The number of respondees who asserted that they were too poor to own a car: 32%

As we are measuring the impact of 20 mph zones, we should be discounting those people from our analysis of this question:

Discounting non-car owners: 70-32 = 38. Therefore of respondees who owned car, only 38% of them got through the year without needing a new mirror.

Discounting non-residents. 54-38: -16! Which seems impossible, unless you consider that many of those non residents will have driven into a 20 mph zone, and so lost a mirror.

Once you discount the non-car owners and non-residents, we get the result we expected: since the 20 mph rollout, everyone in the 20 mph zone has lost one or more wing-mirrors, with the average number being 3. At 15-25 pounds a shot,  that wingmirror-tax is yet another tax on the hard-working motorist.

Causality and co-relatedness
Again, fascinating. Merely because two things appear correlated over time, doesn't mean that one causes another.

In this question Why has congestion got worse in Bristol over 25 years?, 17% said BT added an extra digit to all the phone numbers in the early 1990s. Some people may say "so what?", or even "the growth in Bristol's population caused BT to add more numbers; that same population growth increased the number of cars, hence the resultant congestion". We say something else: It was the adding of that digit which made it possible, in a pre-mobile-phone era, to move to the city. That 17% were right. And from this survey nobody can prove us wrong!

Invalid Survey
Any survey that can be considered invalid from a statistical perspective. Common causes are: invalid sample sets, leading questions, bad measurement, leading questions and bad-analysis, including confusing correlation for causation.

For some examples:

1. Asserting facts about the average weight of Bristolians through an opinion poll with leading questions conducted at the BRI heart clinic of 4-5 people, without even excluding any attendees from North Somerset. That fails: invalid sample set and leading questions.
2. Asserting facts about the entire population of Bristol's opinions on residents parking through an opinion poll with leading questions conducted against a self-selected sample set of some people who care about the subject.
3. Getting your maths wrong when you add things up, divide the answers, etc.
4. Misinterpretation of results. Reaching the wrong conclusions. If you want to reach a set of conclusions, you are less likely to question the sampling or analysis if the outcome agrees with your expectation. This is sometimes called confirmation bias

One classic way to bias a survey is simply to discount the "don't know" respondees and other non-participants. If you explicitly exclude these people from your survey —example by asking different people the question until you get one whose answer is interesting enough to write an article about, you've got an invalid subset of the population, hence the results cannot be extrapolated.

This problem of the don't-know answer is particularly bad in any self-selected survey because the members of the population who don't not hold opinions tend not to participate in it. Instead you get that subset of the population who hold opinions one way or the other.  It is also common for any survey which requires an action on behalf of the respondee, be it jump on a trampoline holding a stopwatch, or fill in a paper questionnaire and then post it.

Summary

As you can see, it is a lot easier to produce an invalid survey than a valid one. More subtly, its very easy to misinterpret a invalid survey for a valid one without knowledge of the sampling and measuring process, and knowledge of statistics.

For that reason, while surveys can provide some data about a subject, you can't consider the conclusions to be valid without knowing about the sampling, measuring and analysis —and any bias of the surveyors.

When you reviewing a survey, you should really query

1. The population for which the survey is meant to be analysing
2. The sampling process conducted in order to get a valid sample set
3. How things were measured
4. If it is some form of poll, the sequence and content of the questions.
5. Outliers: what were they? were any discounted?
6. What compensation have you made for non-participants?
7. How do you defend your claim that this survey can be extrapolated to the population it was meant to.

Alongside invalid surveys, you have bad reporting of surveys. Often this where an invalid survey has been conducted yet the survey is reported as if it is actually represented as "fact" or representative of the entire population. This is a shame that reporters do accept surveys so unquestioningly -as if they did, they'd realise how often politicians use bad maths to make decisions. Or, in the case of Bristol, to generate controversy for the local press where otherwise there'd be nothing in the papers to talk about.

Further Reading

We hope readers found this introduction to surveys and censuses informative and timely. Please practice what have learned by using some of the terms introduced above in your everyday conversation —at least once per day. Example uses

• "Please can I sample some of your chips"
• "the causality relationship between eating chips and being overweight is not clear",
• "your survey is utterly indefensible due to its painfully awful selection bias and leading questions  —your attempt to extrapolate it to any larger population hence so ridiculous you'd fail a GSCE if you sat one this week"

For anyone interested in learning more about this topic, here are some great online books on the topic

• Probability and statistics EBook UCLA. wiki-based book. Notable for a section of uses and abuses of statistics.
• Introduction to Probability. Dartmouth College.
  Foundational undergraduate probability book, with the history of the topic included too. Did you know that early work in probability was funded by french nobility so that they could win more money gambling with their peers? you do now. 
• Think Stats: Probability and Statistics for Programmers, Green Tea Press.
  —great read which makes few assumptions about the ability or willingness of readers to stare at equations. 

Clifton: last days of Christchurch School paveparking

Royal Park is yet to get its markings, so we can view the invaluable space the council will be taking away, ruining with ugly yellow lines

Here, by Christchurch School, the lines already exist -but as they can be ignored, they have a beauty of their own

Round the corner, there's more pavement space. Its inevitable the council will put down double yellow lines here —just so schoolchildren can get to school safely

Yet look at our archives: we've evidence back from 2008 that there's enough space for cars and children!



Given that small children on scooters can already squeeze past parked cars, there is no justification in adding more ugly yellow lines —or even enforcing the ones that are already there

Royal York Crescent: ruined!

Royal York Crescent is the grandest of the Clifton terraces, overlooking the entire city.

Only now, look out the window and what do you see? Yellow lines.

Completely out of place in a historic environment, such as this pleasant rural-esque scene of a pickup paveparked behind some bollards

Utterly inappropriate removal of echelon parking opportunities on a blind corner.

There's only a few days until the car-hating council start enforcing these awful yellow lines

A few more days for the village to live

It's worth remembering that the motorist-haters were pushing for bike parking on these streets.

bike racks would ruin one of Bristol's —nay, one of Britain's—greatest Georgian crescents!