Monday, 28 December 2015

DfT: Number of cyclists on M32 still zero

If you go into a bike shop you can pick up a freebie map of where to cycle in the city —one that's actually good for walking and running too.

You can more easily get a map of where not to cycle. In any overview map of the city, it's the red roads on the cover, along with the junctions between them.


Which is quite a coincidence really, as those are, essentially, the locations of the Department of Transport traffic survey sites

This is why the DfT traffic survey, showing a levelling off in cycle use, has to be treated with some scepticism. Frankly, if the number cyclists on the A370 and Cumberland Basin Flyover, or Temple and Newfoundland Ways was measured at more than zero, we'd actually suspect a measurement error.

Joe Steinsky tears into the numbers, with a graph we've stolen without any attribution.

The sheer variance in that cycling graph shows its flaws —you have to worry about how meaningful it is.

Even so, it's going to be taken up by those people who find it supports their opinions. In Bristol, that's the usual anti-cycling lobby: the evening post, the evening post commenters, random twitter haters and conservative party council and mayoral candidates.

If you encounter it —don't be afraid to ask "where are the numbers of people walking or on a train?", as you aren't going to see any of them on the M32, A370 or Temple Way either.

Out of Bristol, the group people need to worry about is actually the DfT themselves. Their 2013 traffic model predicted a fall in miles cycled after 2015, the data they've published appears aligned with this, so helps congratulate their modelling team on their skills, perhaps promoting them to the DEFRA Flood Modelling project. Which is why the cycling troublemakers need to be pushing back on this, not just asking for the council to collect better data on routes such as the BBRP, suspension bridge, Create Bridge crossing (oh, wait, BRT2 killed that), Prince St Bridge (oh, wait, BRT broke that), the Chocolate Path (oh, wait, BRT2 again), but maybe the castle path, farm pub path, eastville park path, and up through Stoke Park to UWE, etc. And then advocate the DfT to include such data in their modelling of urban use. And include walking too. Because that's a legitimate form of transport and is as much at risk of neglect as the cycling.

At this point, the locals who sneer at Bristol traffic for being car-hating extremists will accuse of us discounting data we don't like, just as they themselves do with all climate change research that brings bad news, models that predict warmer winters with more floods.

For those people, know that we slagged off the survey the moment we encountered it in progress.

This is it: four people on a footbridge overlooking the M32. We faulted it at the time for being an inadequate way of measuring car traffic in a modern city. It is only this week that we discover that one of the people sitting there with a little "clicker" was waiting for cyclists and presumably getting bored at the inaction.


Four people sitting on a footbridge, counting cars on one single weekday in a year. And using that for the traffic statistics and future predictions of Bristol's road needs? That is not modern "data science". In fact, it's more of a practical A-level project —though even there you could do more with a camera and at-leisure replay.

Manually counting one morning in 365 just doesn't produce valid data. Was it a weekday? Which day? Was it a schoolday? Or was it half term with reduced traffic counts? Was it raining? Such experiments may have been a viable strategy in 1963, maybe even 1974 with the M32 open and three Austin Allegros an hour driving down the "Bristol Parkway" to see the shopping wonder that was 1970s Broadmead.

Nowadays, it's a historical relic of a process, no doubt hooked up to a traffic model that considers pedestrians at a junction "a cost", values cyclists as being worthless (OK, that still holds), and considers time in a traffic jam is as cost, rather than a valued quiet texting time between the office and the hell of parental responsibilities.

If you want modern data, throw the hi-viz tops off the footbridge, use the now-rolled out ANPR camera arrays to log vehicle movements, and start to do some decent analysis of the data beyond just "how many"
  1. Split by vehicle type and time of day. Do vans come in earlier or later?
  2. What fraction of the traffic is in-city vs "Greater Avon" vs out of Town?
  3. How many pass out the city on a different route shortly after entering it?
  4. When do people commute in each direction? Is it a simple 9-5? How many are 9:30 to 4:30, vs. 08:00 to 18:30? And does that vary from direction into town?
  5. Do vehicles coming into town on the M32 return the same way? Or do they take a different route? (Not as unusual as you think; from city to N. Fringe, M32 after 09:00 is fast, but for a return between 17:00 and 18:30, Filton Ave has more predictability).
  6. There's apparently a rise in vans. How many are for internet-shopping deliveries vs. independent locals vs. service organisations?
  7. How many people commute from Wales? By motorbike? (it's a free bridge crossing, see).
  8. During school half terms, do many commuters change their driving schedule and/or route?
  9. Do red cars go faster? This'd be a really interesting question to answer, something you could do today by combining the M5 ANPR dataset with one of vehicle make/model/colour. It's not enough to measure the ratio of red to other colours, you need to compensate for the fleet, to make it more "do red Mark IV Vauxhall Astras go faster than other colours"?
Ignoring the final question, which is more of social commentary than anything else, the other questions all directly define the motor vehicle use that's made of the city's road infrastructure. Information that could be used in some way, not just for better DfT modelling, but for moving traffic understanding beyond simple anecdotes.

Transport for London have a data team; they do churn through the oystercards, the C-zone stats: they do understand some of the use of the city? Not Bristol —and clearly, not the Department of Transport, who are still shaping the country's transport infrastructure based on four people and a clipboard.

[footnote: that cover is from a 4th edition A-Z. Look at its rendering of the inner-ring road and see if you spot what's changed?]

Sunday, 27 December 2015

Press, politicians and 100 year floods

This post covers basic probability theory.

The media and the politicians seem to be completely confused by the concept of flood frequency, particularly in the abuse of the concept of "a hundred year flood".

The use of that term creats the misguided idea that you get such a flood every hundred years, and that having had one a few years ago, you aren't going to see another one for nearly a century.

This is shows a complete misunderstanding of statistics and probability. Which for the people being evacuated from their houses you can partly understand —you can't expect them all to have studied maths to A-level or remembered the details. What is wrong is that the press keeps using the same term, along with "20 year flood", misleading the people. And the politicians, they are equally a bunch of Oxbridge PPE-graduates who don't have a single cartesian coordinate between them —but should at least have those science advisors to explain the basics. FFS, there is the whole "Royal Society" which is meant to explain science to royalty, and, given we still live in a feudal state, the crown's ministers, Cameron included.

A "hundred year flood" really means a "1% chance per year flood". Assuming that the effects of the previous year's weather has no bearing on its successors, the probability of having a 1% flood the year after a 1% flood is, wait for it: 1%. The probability of having one in the five years after is, wait for it: five percent. And in 15 years, it's 15%. So the fact that York is currently underwater for the first time since 2000, means that the the two-flood-in-15-year-event, which had ~15% probability, has occurred. Which is not impossible, even for a "hundred year event". In fact, when you start counting since, say, 1995, you are looking at the probability of two 1% floods happening in a 20 year period —which is actually 20%: 1 in 5.

For the curious, assuming that the flood events are entirely independent, it'd follow a Poisson Distribution

Except, certainly within a single winter, we know the events are not independent —if the ground is saturated from previous rainfall, the rivers bloated from previous storms, then the probability of another storm triggering a flood is higher. If the land is already full of water, then it only takes a little bit more to tip things over the edge.

That "hundred year flood" really means, then:

The meteorologists' model of rainfall over a single winter, of the volume and frequency of rainfall, predicts the probability of flood of a specific volume occurring at 1%.

The probability of  a 1% flood re-occuring may follow a poission distribution —and hence the likelihood of multiple floods happening within a few decades is actually quite high.

Floods do appear to be happening more often than even a Poission distribution would apply, so what does that mean?

Some hypotheses spring to mind
  1. The rainfall model is correct and we've simply had the misfortune to have a rare-but-not-impossible series of storms.
  2. The rainfall model is correct, but the estimates of probability of storms within a season are wrong —that is, bad historical data created optimistic estimates.
  3. Year-on-year flood events are not independent.
  4. Changes in the terrain: farming differences, the building of houses on flood plains, etc, changed the runoff of the system, so amplifying the effect of rain
  5. The rainfall model is in fact wrong due to failures such as the failure to consider the impact of global warming on the evaporation of water, the actions and position of the gulf stream, and/or the fact that with warmer air, it falls more as a a liquid ("rain"), than in a crystalline form ("snow" and "hail").
  6. There was a more pessimistic (i.e. accurate) estimate of rainfall, but managerial or political pressure discounted it in favour of one which played down the risks, reducing the requirements and cost of flood defences, and obviated the need to press for changes in the agriculture system within the catchment area
Note also that these hypotheses are not exclusionary. The model could have failed to consider global warming, been based on bad historical data, and not planned ahead for the conversion of flood plains into suburban housing estates —then been downplayed by politicians who disagreed with the answers.. Which, when you think about it, is entirely possible.

That's why the term "hundred year flood" is so bogus. More accurate is "a 1% flood based on a broken or pre-global warming model with incomplete data without considering urban sprawl, and probably downplayed for political reasons". Using the term "100 year flood" does nothing but create unrealistic expectations that the floods aren't going to re-occur, year-on-year.

Someone in the press could look at the model, the data, the politics and determine what's actually happened, then try and explain it in a way which doesn't use terms like "hundred year flood". Because the science is there, the maths is there —and someone needs to hold the politicians and the scientists to account.

[These photos are all from Jan 4, 2014, showing the Avon fairly close to breaking its banks. Avon Crescent was actually underwater in winter 1990

Saturday, 21 November 2015

BRS: Lessons from PDX

The Bristol Traffic team has actually been on a council-funded trip round the world to see what ideas we could adopt in the city to make it more successful. Finally, after months of first class travel and hotels, we have found it -in Portland Airport.

Portland is a relatively small city in the US; less population than, say, Glasgow —and doesn't actually merit an acronym or nickname the way, say 'NYC, LA, Vegas" and others do. Instead it tends to adopt the initials of its airport, PDX. Bristol is similar, except most people in the UK don't know the initials for Bristol International Airport, BRS. Well, use it enough and maybe they'll learn.

Anyway, the first thing you see thing when you get off your plane in PDX is the signs towards some bicycle assembly area. THIS IS NOT WHAT WE ARE ADVOCATING.

A bike assembly area in BRS would only go in if the airport could charge cyclists for using it —and they could only do that by making it illegal to assemble your bicycle near the airport. They'd probably just make it illegal to cycle to it, just as LHR have done by converting the cycle tunnel to road traffic and fining anyone who cycles down it.

No, what's of interest to us is the sign 180 degrees behind the camera here, the one at airport security

Please be advised recreational marijuana is not permitted on flights travelling outside of Oregon.
That's a bit late to see that sign; there isn't one when you load a 14 kg rucksack in as hold luggage, and it is clearly one with implications. If they have to have a sign saying "you can't fly outside of Oregon with weed", then by implication "if you are flying within the state —you can". And they are right.

It is now legal to grow 4 ganja plants of your own: provided you live more than 1000 yards from a school. Imagine that —people would be looking at the catchment area maps of the city to make sure they weren't living near a school; it would turn the current game on its head. House prices would actually go down the closer you were to a school.

It even complicates the university: should their agriculture department start projects to advise farmers on the growing of industrial scale marijuana? Some proposals are on hold because it conflicts with federal funding, and despite the enthusiasm of graduate students to study for a PhD in Marijuana Agriculture, the existing farmers have many years of experience growing weed. All that is happening now is the farmers can do it in public and pay income tax.

Because that's where things are going: industrial scale farming for selling in California and Seattle. It's now got a new problem for the city: how to manage the planning permissions for where to grow and process this "new" commercial product.

It's actually been an open secret in the state that weed was the big rural earner with the demise of logging; it battled with Intel x86 parts for maximum income and profit margins —it just wasn't something that could be discussed publicly. And, unlike CPU foundries, it's something that those towns whose livelihoods had been destroyed by the end of logging could take up, more reliable income than tourism, and generally a wholesome product people could enjoy,

Imagine if Bristol legalised the recreational use of ganja, the growing of plants, and in N. Somerset, full scale agriculture.

It would transform the city!

We would become the powerhouse of the south west, one to rival London! We'd get visitors from all over the country to spend a weekend —and Weston super Mare would become Britain's most popular summer holiday destination.

It would also finally end the gulf between the city and the countryside. The North Somerset Agricultural Show would be transformed from somewhere where range rover owners from near the A370 could turn up and talk about their "crops" to one where range rover owners from near Montpelier could turn up and talk about their "crops" —and the Somerset farmers would listen intently, offer to buy some of the product, then even offer the city folk some paid consultancy.

As the ganja industry grew, North Somerset would move beyond a dormitory county for the city, to one where people would commute too from the inner city, to help "work the farms". Oh, and then there's the pick-your-own harvesting event, which would be a national festival.

And of course all this will bring in money: the tax from the plants, the income tax from the staff, staff who will be earning more than minimum wage as they bring the skills acquired over the years to full use. All those visitors, those tourist events -more money, enough for Weston to move beyond Dismaland as a national tourism event. And all the town will be outside on a sunny summer evening, lighting up in the parks, turning up the sounds of Bristol music, and getting stoned of our heads.

How about it then, prospective candidates for Bristol Mayor? Who is going to look at the lessons from Portland, Colorado, Seattle —and campaign on a "legalised marijuana industry for the greater bristol area"?

Wednesday, 4 November 2015

The new Mass Surveillance State bill

Taking a break from traffic issues, we should note that Bristol Traffic team  has long admitted to building a mass surveillance police state in conjunction with google and facebook —our Datacentre State.

In fact the main difference between us and GCHQ is ours is run from an Ubuntu laptop in the comfy sofa bit of the Canteen. That's just down the road from this painting, behind the riot police in the distance

Now that the new Mass Surveillance State bill is up, we should do a post on how we would implement it and cost it out accordingly. Some request logging  -> Apache Kafka -> Hadoop HDFS pipeline with hourly scheduled MapReduce or Spark jobs compressing the time-series logs a compact and fast-to-scan format like Parquet or Orc. This could then be queried direct via Facebook's Hive, or imported into NSA's open sourced Accumulo column table DB for even faster lookup. Each ISP/mobile telco may host their own "facility", but sticking them all in the same datacentre would ease low-latency cross-ISP queries issued from government computers, while still pretending they were "separate"

In the meantime, let's pick on some talking points that are being used on the radio and TV to justify the bill and make it look like the government listened to feedback

The nature of technology has changed and we must adapt.

People have been browsing the web for 20 years, even skype is about twelve years old. What has changed is the cost of storage. Back in 2008 we were quoting a few hundred dollars for aterabyte. seven years later and the cost is $30/TB and density shrunk to the extent you can get a couple of petabytes in two wardrobe-sized server racks. That's the big change: governments can afford to store all your personal data.

The pages you visit won't be recorded, only the sites.

With the migration of the main web sites to HTTPS, the ISPs couldn't log the pages anyway. There's no concession here: if your browser shows a little green lock in the URL line, the government couldn't record the page. What they can do now is go to facebook and say "Someone at went to at 21:14 on Tuesday: what did they do?" Facebook, will have the rest of the information for them.

This is just like an itemised phone bill.

No. It's like a log of every game you played on your PS3, every program you watched on BBC iPlayer, every photo you took which your smart phone backed up (and where). If you read books on an Amazon kindle —or with the app— its a log of whenever you turned a page or turned back. Spent too much time reading "extremist" bits of the Koran between bouts of Call of Duty and facebook posts? That'll be something they'll be able to work out by looking at the URLs and then asking the service providers for the details. Here Sony may come out the best —unless they start recording chat sessions. Amazon? They'll probably record the ambient light and tablet rotation while you were reading those chapter of the Koran.

We won't ban encryption

They'd only be laughed at if they asked for this. The algorithms (RSA, Elliptic Curve Cryptography) are well known. You can't stop RSA working without banning prime numbers. ECC is potentially even harder. though the fact that NSA are no longer recommending is use implies they don't trust it any more. Either they've found some new math or built some new hardware ... so longer key RSA is back in fashion. All the homeoffice can do is go to FB, google, Whatsapp and say "please store the communications so we can ask for it", then drive round to Apple and say "add a back door to iPhone encryption —we promise we won't abuse it, lose the secret key or otherwise destroy its value.

There is some mention of "informal arrangements" perhaps the government has had meetings with all these people, and said, "give us access and we won't review your tax status". But that isn't going to work with those companies that don't have a UK outpost who can hang up the phone when Theresa rings them. Note especially that some of the best cryptography libraries, Bouncy Castle are explicitly developed in Australia to avoid US regulations on RSA key lengths. And guess what's been ported to Android? Building an Android device-device app with unbreakable encryption is straightforward enough to make it a final year project for a Computer Science course at any of our local universities —how could that be criminalised?

We're only formalising what's been going on.

Ignoring the fact that this implies that previous governments have clearly been granting warrants to log the actions of every citizen, the fact that they've been doing this is a key part of the UK-side of the Snowden leaks. In the US this has led to a rethink of state/citizen rights. Here its leading to the government not only formalising the existing state of affairs, but expanding it.

We won't monitor MPs communications
Bulk data collection renders this impossible. How you know that the person posting to twitter from an internet cafe is an MP or a possible enemy of the state? You can't, you just grab it all.


The core concessions aren't concessions, they are the result of the engineering teams of the government and the ISPs telling them what doesn't work, and the politicians coming up with ways to frame this in terms of concessions, rather than acceptance of engineering and cross-border realities. They've also hidden the key implication: they can now afford to record every single interaction you make with a remote computer, and, with informal and formal arrangements with the providers of those services, get the details.

Meanwhile, your civil liberties have been suspended for the duration of the emergency.

Saturday, 24 October 2015

Governments have the most interesting data. Today: MOTs

There's a new web site., which lets you type in any registration and make of a car and get its entire MOT history. Excluding cars < 3 years old, this means you can get the effective history of a vehicle.

This is fascinating, especially when you use it to look up the history of a vehicle you've sold on (*).

What is equally fascinating, is what is shows about things you can get away with. In particular, holding wing mirrors on with masking tape is not an MoT failure.

You can also get away with: tyres nearly worn down, steering in trouble (wheel balance?), suspension in trouble, exhaust corroded, small damage to your windscreen.

You actually have to wait a year, get those front tyres below the 1.6mm limit as it rubs slightly against the wing of the car before they say "no, time to fix the toy"

By May 2015, this car (WP53JVM, for curious), fails because bolts are missing on the wheels.

Now, you can argue about wing mirrors, suspension, etc. But driving around with bolts missing from your wheels? That's not just cause for keeping the car in the garage, that should be cause for arresting the driver for some offence related to driving in a way to endanger everyone nearby.

Anyway, it's interesting data, and you can get it for any car.

Which means you can now do some interesting data-science projects —including some which would be something schoolkids to do as "maths in the real world" projects.
  1. Look at all your friends' and neigbours' car histories and see whose is the one most likely to cause a crash. Then make a note of who never to accept a lift from, especially at night, in the rain or winter conditions.
  2. Do a census of the entire history of all cars in your road over 3 years old, counting the pass/fail ratio as well as numbers of advisory issues. Then repeat this for other parts of the city, to determine the different vehicle quality statuses of the region.
  3. We've always asserted that cars in montpelier only need wing-mirrors for the MoT. Does the data imply this?
  4. Use the historical mileage data of cars over four years old and use this to determine the average annual mileage of cars in the same streets. Is the MOT failure rate proportional to the miles across all parts of the city, or are some cars continually failing even with short mileage? Those are potentially the vehicles driven more around the city.
  5. Using that historical data, have the miles driven by residents increased or decreased after the RPZs were rolled out? What about people who don't live in an RPZ yet have jobs in the city centre or nearby?
  6. When buying a car, look up its history. It is a sign of a car that is maintained, or one neglected?
  7. Look at some lorries. Is their failure rate better or worse than other vehicles? What about vans?
The scariest thing to consider is this: the MOT certifies that a vehicle was considered safe by MOT standards for one single day. The car above could have been driving around with broken windscreen wipers, failing suspension and missing wheel bolts for 364 days before it failed its test. After being fixed, it now has another 364 days for its brake pads to finally wear too thin, tyres to wear out, those coil springs to finally corrode through.

Drivers like these are potentially some of those who complain about cyclists "not having MOTs on their bicycles". Well, with drivers like that, who cares about the state of the cyclists' bikes, other than whether or not both their brakes work? Because they aren't what you have to worry about, whether walking, cycling or driving. It's the people driving round the city in a VW golf with underbolted wheels, worn brake pads, failing suspension and defective windscreen and wipers.

To close, then: a competition for the weekend. Pick a car you see ~ 10 years old, put in its history and find out exactly what it's been failing MOTs for. We want the most dramatic reasons -and so far "missing wheel bolts on two wheels" is it.

(*) Actually it wasn't that vehicle, which was WP53JVO. Getting the last digit wrong turned up what must been another of the last batch of MkIV Golfs to leave the VW dealer.

Wednesday, 21 October 2015

Bristol's 2015 Bike Survey. If its so wonderful, why do twats swear at you for cycling?

Sustrans have just published a 2015 survey on use and opinions on cycling in Bristol. This is available as a PDF for anyone who still prints things, and, on Page 2, comes with a sepia tinted photo of Our Glorious Leader for anyone who hasn't seen him recently.

Lots of people will be praising this, so we'll be ruthless and go the other way.

First issue: where do the numbers come from?

There is a full PDF of the methodology, which is what all surveys need: Something to back up the dataset. This shows that the Bristol survey was a phone survey of 1100 people, selected by random dialling, and quotas to match demographics in the area, then some 300 booster surveys to find cyclists who have real opinions on the cycling facilities.

One of our team members got a survey call, so we know two facts about it
  1. It was made to a landline. It therefore implicitly excludes all households without landlines. Ofcom's figures would imply that excludes 15% of the UK population from the survey; there's no data for Bristol itself.
  2. It was conducted mid-afternoon on a weekend. This may lead to selection bias towards boring people who don't have lives, parents stuck at home with children included.
What we don't know is how wide the survey went. Did it cover the bits of S Gloucs that is the part of Bristol full of people who hate speed limits and residents parking? Or did it only cover BRS and Avonmouth?

Second issue: why be so positive in the interpretation

Here's the negative view of Page 5
  1. 28% of people don't "like to see people out and about on bikes". Cyclists: these are the people shouting at you.
  2. 32% do not believe things would be better if people in general rode bikes more.
  3. 26% do not believe that more people riding bikes would make Bristol a better place to live and work.
  4. 46% do not believe that things would be better if friends and family road bikes more.
  5. 52% do not feel that they should ride a bike more.
  6. and from p10: 30% of residents would not like to see more investment in cycling in Bristol.
This may be excessively negative, as the PDF doesn't differentiate "no" from "don't know". All we know is that it is not positive. But lets go for the worst case here.

Over a quarter of the sample set in the survey don't like to see people cycling. More than half don't feel that they should ride a bike more. And, nearly half (46%) don't even want to see friends and family riding bikes more. Maybe because that would create an inconsistent view of cyclists as outgroup vs friends-and-family. We don't know —the data isn't there.

What we see then, is a divided city.

Now, what other bits of the survey are interesting?

P10: bike routes

Notice the popularity of traffic free cycle routes and protected bike lanes amongst all current and potential users.

Notice the complete disdain for shared pavements amongst non-cyclists and experienced cyclists alike. The fact that even the "don't ride a bike but want to" group don't like shared pavements shows how the two-track route policy in the UK, "magic paint on the roads and shared cycle pavements" doesn't even deliver for the people who would like to cycle. Time to knife the baby there.

Similarly: nobody likes bus lanes except for experienced/regular cyclists. Even there, ask them "do you like to be stuck behind a first bus in full early morning black smoke mode" or "do you like to have a bus right behind you?". These are details we'd like to know.

P11: demographics

Older people are under-represented. The pie chart doesn't actually show the number of respondents who cycle vs. the demographics of the city as a whole, so it' not that useful. Let's assume that yes, there are less elderly people. Look at the pie chart next to it. ~50% commute, some (2%?) to school and then 4% to college or university. We're going to take a guess here, but you won't see many of the 55+ going to school or college, or in the 65+ range commuting. You'd expect to see a reduction. More interesting, the smaller 45-54 range (14%) vs. 35-44 (23%). 

The 16% of of people riding bikes who identify themselves as black or minority ethnic —the same as for the city. This is interesting, as it implies the claim that cyclists are all white middle class men is not true in Bristol. But we still see 69% of cyclists identifying as male vs 31% female, showing significant gender disparities in a city where the percentage of sexes is approximately equal. And there is no income related data to look on that axis.

Between 2013 and 2014 the number of trips made by bike increased by 4%

What does that mean? That the percentage of all trips made in the city increased by 4% in one year? Or that in 2014 the number of bike journeys was 1.04 times that of 2013? And if so, how does that compare with the percentage increase in: car journeys, walking, train and bus? More? the same? Less? We need more context for that sentence to parse it correctly.

P13: Metrobus

"with the Metrobus giving hard-pressed commuters even more travel choice, our roads will become even less congested, and better for people on bikes and walking." Someone paid sustrans to write that. Because it should be "with the Metrobus making cycling harder in the city, our roads will stay a congested mess, and while it is being built the centre cycle-crossings and Create centre bridge have gone"


There is nobody in any of the 30-40 photos looking wet. This is an unrepresentative sample of Bristol days. We'd have expected waterproofs to be visible and needed in at least 25-30% of them.

p8: routes

There's 116 miles of "bike route", "79 miles traffic free", and "1 mile of protected bike lane". 27% of people live within 125 metres of a cycle lane, track or shared use path. Well the survey showed that everyone thinks shared use paths are worthless, and "bike route' is vaguely defined here. Presumably it includes anything painted on tarmac, which is effectively meaningless.

Page 12 follows this up with some assertions that 1/3 of morning rush hour traffic is bicycles, and that Gloucester Road has comparable numbers to the railway path. Here is Gloucester Road outbound at 16:30 on this very weekday. As such, it's not something we've been saving for a special occasion, simply a normal weekday, with here the passenger of WU56JKV swearing at the cyclist as they go past.

The driver appears to be concerned that the cyclist "was in the middle of the road" while cycling past the parked cars and the road junction where the traffic island means that the middle of the road is the place to be. They were clearly concerned enough to shout "get to the fucking side". The fact that they'd wound up the window when next passed shows that they hadn't expected to be passed again, as they had to go to the effort of winding it down to make more hand gestures later.

As for the reason for the abuse, "middle of road" was it, though they seemed unable to proceed even after the cyclist had expressed their apologies and invited them to go ahead. It's almost as if they were, to use a phrase, four fuckwits without a fuck or a wit between them.

  1. You can't see it in the photo, but the front tyre was pretty much smooth on the outer 1/4 of the tyre. Tapping the reg# and make (ford) into the MOT history site shows the MoT is due soon, and they have a history of bald tyres. We'll check back in a month to see if that tyre earned a failure. If not: they've had to suspend it.
  2. At 0:33 you can see that one of its brake lights is dead. This is a defective vehicle.
  3. Given that they stay in the same position from 0:33 to 1:33, a minute at a red light, perhaps it is their frustration at having to wait so long which is leading to their anger management issues.
  4. Note how everyone in the vehicle hates the cyclists being there. These are all from the 28% of people that don't like to see people out and about on bikes.
  5. As this is after 16:30, anyone parked in the bus lane is illegally parked and can earn tickets; its generally the buses that suffer the most from parked cars, but you can see a few times where the cyclists have to swing out.
  6. The GPS route map may be accurate, but the speedo is clearly confused, has some bad weighted-moving-average parameters, or at least one of the GPS satellites has just fallen out the sky while still broadcasting its position.
  7. The actual Strava numbers for this segment time that cyclist as 19.7 mph, top 100 of the 3500 riders logged, fastest of October to date. In a 20 mph zone, this is not someone you have to wait for.
  8. That intermittent bit of paint on the side of the road is probably 2 miles out of the 79 miles of bike route, and definitely part of the kind of cycle lane which 27% of people live with 125 metres of.
The last is interesting, as it says "is that all you can do?", "how does this stop cyclists being sworn at", and "what would the numbers be if the 75 cm path didn't keep disappearing under buses and vans at corners?"

Regarding the passenger of the car, we're going to try a new experiment today. Report them to the ASPoliceWest and ask for a caution for abusive behaviour or a section 59 ASBO. The ASBO strategy is to see what excuse they will make up for not issuing one, as they can't cite court costs, leaving only "we don't think swearing at cyclists is antisocial". Let's see, shall we?


We're seeing a polarised city here, one shown in both the survey results and today's field test of a ride up Gloucester Road, —a road the survey calls out as a success, but which we document as "par for the course".

It'd be interesting to know the postcode split of the like to see bicycles/hate to cycles answers, and their demographics. While there appears to be an ascendant movement to cycling in the city, the anti- forces are a significant number and do form a noisy minority — not just swearing away at passing cyclists.

Saturday, 17 October 2015

Autonomous vehicles: Google are the new British Leyland

After spending a month with our strategic partners in a privatised-PCSO state, you soon get fairly used to the sight of Google autonomous cars. There's two types, the original Lexus models, and the smaller kitty cars. The latter are clearly designed to avoid scaring people witless that machines are taking over the freeway. It's as if in Terminator, the T1000 had been dressed up as a telly-tubby after being beamed back in time. Sarah Connor and compatriots would have been so busy saying "Oh, isn't it cute" to notice they were being shot to pieces by Skynet.

Maybe google should buy a kitty car and paint it up like Schwarzenegger in the final stages of Terminator & see whether it gets cut up less: an interesting little field trial.

So what's like to drive round town when there are these things on the route?

Here is one spotted during a morning commute on El Camino, the road where bus lanes are being opposed as autonomous cars will solve all problems.

It is legal to use a phone while stationary, so this photo was legal. However, the photographer is clearly not paying attention. Nor are the two googlers in the lexus, as they chat to each other -but they don't need to.

Which promises a wonderful future, were it not for the fact that Google's entire computer infrastructure is built on the decision that rather than spend lots of money for hardware that doesn't fail,  just buy cheap boxes and let the software deal with the failure rate. For example, whereas even your home network store can be "RAID-5" for redundant data storage, Google's filesystem, GFS, just stores three copies of your photos and re-replicates a copy if one of them goes way or gets corrupted. That is: google accept things to fail and hide it from the user. Similarly, anyone who has ever owned a Google Nexus phone will know that they're as unreliable as a mid-1980s Mini Metro. A couple of months ago, Google shipped an update where the flash and the photo taking were out of sync. The flash went off, then the photo was taken after the flash had gone. What kind of QA process lets that out of the door? Unless they used the Volkswagen strategy, "detect when you are testing the phone and have the camera work", or their test image was a black object against a black background, detecting flash/snap synchronisation failures during the test process should be trivial. Which implies google did near-zero testing, but instead pushed the patch out over the wire -to their own Google Nexus phones- and then waited for complaints to come in.

Can you trust these people to build cars? Cars which are all required to reach their destination with their payload alive, rather than ones where its OK to have 99.3 percent arriving, and a paper "Failure trends in large self-driving car populations" of esoteric interest to those who work in computer hardware? Cars when you want things co-ordinated like the camera and the brake pedal, so it it sees a lorry coming it will stop in time, rather than 15 seconds too late?

It's not just that they're just out of their depth, they've made it a fundamental tenet of their system architecture: things fail, get over it. We'll hide it the server software, while client side we'll just push out an update once we get bug reports coming in.

Which means anyone who owns a google car would be reluctant to accept that update; you'd wait a week to see if The Register was warning of bugs in the steering or braking systems before you hit the "accept" button on a patch, that is, unless you wanted an emergency fix to some problem like "doesn't recognise oncoming HGVs"

Not in our photograph, to the left of our photographer, is someone in a Tesla-S electric car. These are the status toys of the electric world. Not toy cars like the nissan leaf, but performance luxury vehicles where the electric feature is not just to keep costs down on the commute, or to allow you in the car-sharing lanes when on your own, but to show off, "my facebook stock is up and I can afford to be smug".

The driver of the Tesla is not only looking down at their phone, they appear to be falling asleep while they do it. Every so often their head jerks up, not in the "I'd better look to see if the lights have changed" style, but in the "I'm falling asleep but shouldn't" style. Whatever their friends are up to on Facebook, it's not interesting enough to keep them awake on the commute.

So which future do we have to look forward to?

  1. Self driving cars from a company whose view on what reliability constitutes "acceptable" is on a par of what British Leyland thought in 1978.
  2. Non-autonomous electric cars driven by people who can't even stay awake long enough to read messages on the phone.

This is the future —and either way it's pretty bleak.

Saturday, 10 October 2015

The spectator discovers sectarian Bristol

Once every 18 months, the Spectator magazine covers Bristol with an article. This is something we residents we have on our "things to look forward to" list somewhere between "Shopping in Asda Bemmy on a Saturday" and "getting stuck on the M4 because there's a rugby match scheduled to start in Cardiff soon".

This year we are blessed with many opportunities to get stuck on the M4. We are also graced with the latest spectator article, Bristol, the European capital of green nannying and bureaucracy.

Here are the opening three paragraphs:
I am stuck behind a big yellow recycling lorry in Bristol, which this year became the UK’s first European Green Capital. It is collecting food waste from the special brown bins we have to use, and the stench is horrendous. Behind me are about another dozen cars and, sad to say, I fear that not all of them have turned off their idling engines.  
Squadrons of recycling vehicles invade every day, blocking our narrow Victorian streets and causing misery and mayhem — starting with the school run: ‘Dad! I’m going to be marked down for a “late” again!’ ‘Sorry son, but these teabags mustn’t be allowed to rot in landfill. And besides, we have our city’s green status to consider!’ 
I am not against recycling — just the extreme methodology the city has adopted. Bristol is now so over-the-top with it all that bin day involves five or more different bins collected by three separate diesel–powered lorries. And I have a theory about why these mobile compost heaps insist on working through the morning rush hour: it is all about our city’s war on the car.
Mr Miserable then actually goes on to make the point that Bristol has gone from being the city of ganja and Trip-hop to one of painted road regulations, blaming "green city europe" for it. Well, he may have a point. Certainly there is a visible split between those people who were happy with "The way thing were" and the progressives,. The "way things were" brigade are still sulking over the (last) rework of The Centre, the loss of the rickety flyover, and probably even the loss of the road over College Green. Notice how roads are the key source of resentment. Similarly the progressives are full of hope that with an RPZ and 20 mph limit all those people sulking about stolen roundabouts will suddenly choose to cycle happily to work.  Well, the sulkers won't be doing that out of ideological reasons, even if their GP says they need to do it for their emergent Coronary Heart Disease and Type II Diabetes.

Ironically, both groups have lots in common: they all think Bristol being "european green city" is taking the piss, and that Metrobus is a disaster in the making. Nobody anywhere can be found to defend Metrobus except bus companies, and the engineers in WoEP who find designing continuous bike routes too boring to bother with.

Anyway, on a standard of the Spectator's usual coverage, no worse than usual, and it doesn't laugh at us rural folk who live outside the Home Counties.

What is irritating though, is the whole theme of those quoted paragraphs. He has spent a fifth of his article citing being stuck behind a bin van on the school run with the other parents as evidence for the council's "war on the car". That's it: stuck behind a bin van.

Now, nobody likes being stuck behind the rubbish or recycling lorries, but here is a key aspect of them:
they come on the same day every week
Admittedly, whether it's a brown and recycle week or a black-bins-too week is a mystery to all, but that is addressed, as everyone does, by sticking them all out on the street. Any that don't get collected can be left there for the following week. Because, as noted, they will be back exactly seven days later, except around Christmas and New Year -but there, as a gift to the parents, the council allows them to take off three weeks worth of school run, so the schedule is irrelevant.

Because bin day is so regular, you soon learn which days the lorries come out on the rat-runs between your home and school, which means remembering the 1-2 days a week when you have kick your child out of bed a bit earlier and say "we need to go to school now, get up you lazy bastard".

But no, clearly Anthony Whitehead never remembers to do this on the morning after he (hopefully) helped stick the bins out. Which implies its more a war on "lazy and forgetful parents".

Having failed to learn a useful strategy for avoiding being late one day a week "get out of the door 10 minutes early on bin day", he is instead stuck in a line of cars trying to compose his magazine article.

This is where he makes his second fatal mistake. At the moment he realised that he was blocked in, and that he wasn't going to get the child to school in time, instead of foaming off at the council or writing an article for the Spectator, he should have put the handbrake on, turned round to the child and said "get out of the car and walk from here".

Because that is the real split in the city; those who drive their kids to school and those who don't. For a parent driving their child in to suddenly say "get out and walk" is as unthinkable as anyone who works in Clifton using public transport to get there.

Yet still the council tries to force families to walk their kids to school. And it's a war that's been going on for decades

Here is a shocking video showing hordes of children forced to walk to school -even those whose parents are important and own more than one car.

Listen to their happy laughs over the birdsong! Look to how their irresponsible parents let them scoot ahead to the next junction, rather than holding them tightly by the hand on the dangerous journey from the front door to the back seat of their Euro-6 certified crossover SUV. Note the road closures from Ninetree Hill to Freemantle Square, and the later one just before Colston School -and see how they have killed off the traffic-flow-enhancing through traffic. Observe the near-complete lack of traffic apart from a white builder's van, en route to a wage-earning job, one car going up Cotham Brow and a bus.. Note specifically, the presence of RPZ paintwork in the Kingsdown and Cotham North zones are preventing any of the workers Bristol depends on from driving round in circles until they can see a free corner to park on.

All these children are being deprived of the opportunity to snapchat their friends from the back of Crossover SUVs stuck behind bin lorries! All their parents are deprived the opportunity to show off the size and ostentatiousness of their land-barges, hence provide any form of visible wealth to indicate the social status of their offspring! You can't see who is poor and who can afford a car! And long term -these children will grow up as yet unable to grasp the core tenant of Bristol: you need a car to get on.

Sunday, 27 September 2015

"VW cheated —so we need 30 mph!"

Someone called, entertainingly, Pointer2null , comments on one of our 20 mph posts and argues that:

Because VW cheated its customers and governments round the world, we need a 30 mph limit.

It's the pollution, you understand.

He cites two papers, so let's look at them.

An evaluation of the estimated impacts on vehicle emissions of a 20mph speed restriction in central London, City of London Study,  2013:

The opening paragraph says
Average speed models suggest that a lower speed limit in urban areas may result in higher pollutant emissions. However, the stop-start nature of traffic in central London means that such a method may not be suitable, and further investigation is required.
That's the scientific way of saying "its the acceleration from 0 mph that uses fuel, stopping wastes it —so simple models of constant speed are unlikely "may" to apply. Give us some more money and we'll tell you. Actually, the VW debacle has shown that some real-world experimentation would be the strategy. Fit a car with the sensors, drive round an area the month before a 20 mph rollout, then the month after -and see what changed. Back-to-back tests should be relatively accurate, though term-times and weather patterns are factors to consider.

Looking at both the 30 mph and 20 mph modes, they noted that in a 30 mph zone more time was spent accelerating (==higher RPM), while the cruise at 30 mph may more fuel efficient, its not there for very long. with slightly different roads in the study at 20 & 30, you could argue about whether the cruise and acceleration profiles would be the same at 20.

They then go on to conclude
  • It is concluded that it would be incorrect to assume a 20mph speed restriction would be detrimental to ambient local air quality, as the effects on vehicle emissions are mixed 
  •  The short-comings of using average speed models is highlighted, with the specific example of the potential to underestimate emissions of NOX from diesel passenger cars
Pollution metrics were taken off stated manufacturer levels, so, as we know: massively underestimating the pollution of the diesel fleet, while much more accurate for petrol. This means well have to discount one paragraph
Emissions of NOX and CO2 are seen to be higher over 20mph drive cycles for petrol cars and generally lower for diesel cars. PM10 emissions improve for smaller vehicles over 20mph drive cycles (less than 2.0 litre engine size), but are shown to increase for larger vehicles. The order of magnitude is such that future trends in fleet composition will be important.
The authors of the paper would really need to take the real-world figures for petrol and diesel and model the pollution levels based on those numbers, using the acceleration/speed profiles gained in this experiment. Perhaps a future paper is forthcoming.

20mph roads and CO2 emissions, The AA, Undated

This isn't a paper, more a press release. You can see it in the headline, Lower limits can increase fuel consumption and CO2 emissions. Scientists would be more circumspect, and use the word "may" in their work, especially for one single experiment.

The article is about an AA field test measuring fuel consumption in petrol vehicles. Like the CoL paper, it calls out stop-start driving and implicitly the acceleration profile, as the real killer:
  • Change 30 mph zone to 20 mph: increases fuel consumption by 5.85 miles per gallon, or 10.1 per cent.
  • Add speed humps to a 30 mph zone: increases fuel consumption by 27.3 miles per gallon, or 46.9 per cent.
It doesn't look at diesel, and the initial measurements are from the steady state "driving at 30 with no traffic jams". The Millbrook Proving Ground they mention does have a "city track",  hopefully that was the one used. A real paper would provide such information.

What it shows is that speed bumps are the enemy of breathable air. The fact that the Bristol rollout doesn't have them, must therefore be viewed as a good thing.

Comparing the AA press release with the CoL study, it is the CoL one which is scientifically defensible. They discuss the experiment in detail, how they cleaned up the data, the maths to reach the conclusions. And even in the conclusions they state their uncertainties. They are scientists? The AA: an organisation which came to the experiment with an expectation of what the answer would be, ran a field experiment which is unlikely to reflect an inner city, didn't describe that experiment very well —and came to a simple headline conclusion which failed to represent the uncertainties in the findings.

Were that to be be a paper submitted to the Bristol Traffic review team, it would have been rejected due to lack of scientific rigour.

PointerToNull, reads them and comes to the conclusion:
It's all over the news today - the NO2 figures for diesels has been faked. So this make the decision to force all petriol vehicle to observe a speed that INCREASES NO2 emissions by 8% even more short sighted (this is a measured increase by the study and not a claimed one by the makers). Given the state of diesel, petrol will probably be the dominent fuel and so in a single stroke of stupidity, all the gains made by better engine technology in petrol vehicles over the last decade has been wiped out. To press the point, the number of people who will die from air pollution will increase more than those who are saved by slower vehicles.
We're not going to disagree with anything here. They (he? she?) focus on the better of the two papers, and while skipping the "more data needed" bit of the conclusions (academics like that, it's how they get more money), makes the case that speed limits should be driven by what is optimal in terms of pollution profile.

This is a dangerous argument to use. Why? Because to say "we must choose our speed limit by optimal CO2/NOx levels", then you have to be pushing for the motorway limit to be 60 mph. Fuel economy drops significantly after that, and pollution levels increase.

Anyone advocating 30 mph urban for the sake of pollution levels, must also advocate a 60 mph limit, else they are picking data to suit their opinions.  If you did care, you won't drive short distances on cold days, or when pollution levels are already over the limits. 

Then there's also the painful fact that inner bristol's air pollution levels are beyond the legal limits, even before the 20 mph rollout, and includes the M32 corridor.

That is

-Bristol's NOx problem predates the 20 mph zone.
-it seems to correlate with some of the main bus routes: A38 and stapleton road
-it also covers the M32, which had a 60/70 mph limit in 2012.

Leaving the limits at 30 mph would have done nothing to address this problem. And while VW and friends were promising to everyone that all they had to do was wait for the Euro6 rollout, that's not going to cut it either. Which means we'll have to try other things.

The goal of the 20 mph zone is to get more people walking and cycling, not driving their kids to school in turbo-diesel cars. Then if we can get people in the core to not drive on short journeys, potentially increase traffic flow overall.

The future of urban cars is probably hybrid, maybe electric, though the economics and logistics are still dodgy there (expect some post on Tesla vs Google soon —TL;DR you'd have to be driving a lot for a Tesla to make sense; if you buy one you almost want to drive more to reduce that cost/mile). Certainly we don't need to be looking ahead to city centres with diesel, because dieselgate may be the trigger to accelerate restrictions or C-zone charges for them in Bristol, possibly starting with the RPZ.
"the number of people who will die from air pollution will increase more than those who are saved by slower vehicles.
This is potentially -and terrifyingly- true. But the response to NO2 problem should not be 'let's have 30 mph limits in town', because that will not address:

  1. The fact that with the average speed of cars in Bristol being ~16-18 mph at peak hours, even on the M32, the 20 mph limit is irrelevant at the time most cars are driven in the city.
  2. The fact that as fuel economy on motorways peaks at < 60 mph, if we want to address NOx pollution from motorways, the peak limit should drop from 70 to 60.
  3. The lack of data we have on what percentage of Bristol's NOx pollution comes from buses and taxis. If we knew, then from a pollution perspective, that could be an area to focus on.

To close then, we congratulate Pointer2null for digging up an interesting paper on the impact of 20 mph limits on city of london's pollution levels, and may email the authors asking for any planned recalculations.

Assuming that Pointer2null going to become the city's advocate of pollution-scient-driven-transport policy, we also hope to see any papers they can now dig up on effective speed limits for fuel economy and pollution on motorways. Now that £80M has been spent on the Managed Motorways, it would now be possible to drop the speed limit there on high-smog days. Having some insight into the effectiveness of this would be something to help shape regional transport policy.

Tuesday, 22 September 2015

VW TDi rigging: —but why?

The VW TDi rigging story is pretty serious; it's the third big automotive software disaster —and we haven't even covered disasters #1 and #2 yet.

Which are, for reference:

  1. Toyota's dev team being utterly incapable of writing software in accordance with modern software development practices  —with the failing accelerators being only one of the consequences of this. None of those people should ever be allowed to write code for anything more safety critical than a flash-based web advert ever again.
  2. Jeep's "Jeep Cherokee online edition", feature, where every model shipped in 2015 had a modem scannable on the network, an 0wnable infotainment console and an engine (on the same single network), whose network stack never once questioned why the mp3 player was sending messages to the transmission to turn itself off. Those engineers shouldn't be allowed to code for anything directly or indirectly attached to the Internet —which, in modern society, means they can't even code a light bulb any more (do watch that entire video for terrifyingly accurate summary of the current infosec world).
  3. VW's US TDi models detecting when they are pushed through their emissions control exam and so not being polluting for the hour or so it takes. (this would be good for MoTs actually; it would go down well with our business plan to rent VW wingmirrors for MoT tests)

Now, one of our team members does own an (ageing) VW TDi barge, and while it is frugal —even at 20 mph, we add—, it has some limitations, specifically it is a lot less responsive than the VW Passat 1.8T "wagon" which used live in the double garage up in the Pacific North West. That car had a ski box in the roof, Z-chain snow chains in the back and the ability to make it from that garage over the mountains and into in he car park of the ski resort in 2h30, —all for less than $20 of "gasoline".

Because that is the surprising thing about the US adoption of turbo-diesels: from an EU perspective, the US give away free fuel to their citizens.

Being evidence driven, here is our evidence, a receipt from ten-days into the Bristol-Traffic-strategic-meetup-with-the bay area self-driving-car/police state manufacturers. Driving, for reference a VW Jetta 2.0 16v petrol engine with automatic transmission rented for $250/week.

This is for seven days worth of commuting across mountain view, 30 miles a day,  plus the weekend leisure activities silicon valley is famous for (going to shopping malls and buying new apple hardware in the belief it will make your life more satisfying).

Assuming 150 miles over the weekend plus the commute, 30x7 + 150 = 360 miles.
The receipt is for ~13 US gallons, 27 mpg. In UK Gallons, that's 32.7 mpg. Not bad.

Now look at the total cost, $44.32 —that's £28.63. For 11 UK gallons. Which is £2.65/gallon —or, more tangibly, 58 pence a litre.

58 pence/litre? And people think the fuel economy of that car was so bad that they had to switch to a TDi model with higher economy. That is, they felt "gas" was so expensive that they had to pay a premium for an engine with more cabin noise, bounces up and down more when you are trying to text at traffic lights and whose overtaking ability, once you consider the gear-drop and turbocharger spinup will only take place once you actually hit the accelerate pedal, isn't actually that good. In contrast, a petrol Jetta is, compared to a UK petrol-engined Golf, half the price per mile and equally nimble, albeit somewhat crippled by its saloon-car design preventing it being so good for throwing things in the back or for parking in smaller spaces. You would have to be doing a lot of long-distance driving to actually justify swapping the petrol engine for the diesel turbine.

That's what VW managed to pull off with their software: not the rigging of the emissions —but the convincing of the US customer that they'd actually have a better time in a Turbo Diesel.

Sunday, 30 August 2015

Bristol vs Self driving cars

One little sighting over by our strategic PCSO-state partners, Google, are their self driving cars.

They are utterly not-ready for Bristol. You can see this at a glance

Not only is there a bollard on the roof, there appear to be sensors coming out of every corner.

Here in the city centre we have a word to describe vehicles with wing mirrors attached: visitors.

While having wingmirrors helps you in certain out of town operations, primarily changing lanes on the M4, in town it actually hurts you: it makes your car about 30 cm wider so significantly reduces your choices as to where to drive. And, as their presence broadcasts that you are not a local —but instead have a vehicle you care for— you lose every negotiation that takes place, be it a junction or a "who will give way first" interaction. And, when parked, you don't have to bother looking out the window when you hear the sound of a car-on-parked-car interaction, unless it is so loud that you fear it may be some damage needing bodywork repairs.

Now put something on every corner of the vehicle whose presence is actually critical for the self-driving feature to work. Sensors attempting to detect what is too close, so the multi-layer neural network that is is google self-drive program can make a decision as to what to do next.

It's doomed.

That's before even looking at what complexity of road the cars are exposed to. This road, "Castro", is a complex environment on the basis that it actually has people walking. Yet it is wide-enough for oncoming vehicles to pass each other, all junctions are nice simple right-angled crossings, and visibility is reasonable.  Now imagine taking a car trained here and trying to drive down Clifton Vale, the one with the blind z-bend you have to share with oncoming traffic. The car would just give up. And it would share the experience with every other google car, saying "avoid this road". Before long whole swathes of the city would be blacklisted by Google cars, cars who give up on account of their paintwork and external mounts being valued.

Which, when you think about it, could be no bad thing

Saturday, 29 August 2015

where are the speedo-watching crashes?

Here are the two petitions to look at

Speeders: Scrap the 20mph limit in Bristol and restore common sense  now at 8045
Keepers: Keep and extend 20mph limits now at 1680

One claim in the Speeders' petition is
"roads will only be made more dangerous with frustrated drivers and people watching the speedo rather than where they're going!"
We haven't noticed that ourselves, as we have a special speed limiter in our car called "the gear stick". Put it into "speed band 3", or "3rd gear" as it is sometimes known and it burbles along quite happily at 20-24mph, except in the special case that someone drives so close that you can see the driver's nostril hair and you slowly lift your foot of the accelerator to drop to precisely 19 mph just to see the expression on the driver's face in your rear view mirror.

Anyway, it may be that the speed petitioners don't have manual transmissions, or are somehow unable to determine road speed, and do have to look at the speedo all the time.

This is something we can test now that the central 20 mph zone is over a year old. All we have to do is look at the data.

One irony here is that if they do occur, the fact that they will take place at 20 mph means the police aren't likely to get involved. Any crash involving pedestrian, cyclist or stationary object will be less likely than at 30 mph to injure anyone, so they may not get called out. Indeed, even the insurance companies may not get a look in if people care about their no claims discount. head-on collisions will still have 40-50 mph of energy, so are more likely to show up. This means official data sources: —police and insurance— may show a reduction in RTCs even if there has been an increase in RTC events.

We ask the speeders, then: where are the speedo-watching crashes?
  1. How many crashes in 20 mph zone have you personally been involved in where you or another participant was looking at the speedo at the time?
  2. Have you heard of any such crashes —and do you have the contact details for us to follow up on this?
  3. Is there any other evidence for an speedo-watching crashes in the central bristol zone?
We've had the zone for 18 months now, with millions of journeys in it by now. If speedo-watching crashes are a risk in 20 mph zones, we should have seen some. 

If we don't have the any signs of speedo-watching crashes, then, it could be due to
  1. They are happening, but the massive lower energies in the collisions cause them to be unreported
  2. That whole claim about "watching speedos causes crashes" is bollocks.
#2 is the null hypothesis: 20 mph limits do not cause speedo-watching crashes, is the one which has to be disproved to a significant degree of statistical confidence before it can be believed.

We put it to the speeders then: show us the data.

Now, assuming, on the off-chance that there is the data, that speedo-watching does cause crashes, hence 20 mph zones are more hazardous than 30 mph zones, why do the petitioners still propose lower limits by schools?

Either 20 mph zones are more dangerous due to speedo-watching or 20 mph zones are safer round schools.

So if that claim "20 mph is more dangerous" isn't utter bollocks, then, if the speed campaigners really believed it, they should be pushing for 30 mph zones round schools "for the children".

Speeders: show us the data —you've had 18 months to collect it.

(photo: kid scootering to school outside Christchurch School, Clifton, pre-RPZ)

Friday, 28 August 2015

Unhappy speeders

In our ground breaking analysis of the geographic distribution of the speeders and the 20 milers in the city,  we were picked up on for our statement "They must live very unhappy lives."

Good catch. Judging by the reaction to the post, we should have concluded "they are very angry people"

It's as if they spent a lot of time in traffic jams or stuck at the lights -blaming George Ferguson for every minute of their wasted life

We were particularly called out on our assertion that the 38% of out of town petitioners on the "right to speed" campaign don't count.

Specifically, the accusation of misinformation came about because of the T&Cs of the council's petition policy, which states
If your petition has received 3500 signatories or more from people who live, work or study in Bristol it can then trigger a full council debate [see page 5] and if this is the case we will discuss with the lead petitioner the options for enabling this to take place.
We are not attempting to misinform anyone. Look at what we wrote
Of the speeders, 38% of them don't live in in Bristol. Which means they are, as far as Bristol elections are concerned, as relevant as residents of the Isle of Wight. They don't have a vote, all they have is a whine.
See that? If you live outside the city, you are electorally irrelevant. Which may or may not transfer into the decisions about the region and its transport policy.

If you lived out of the city, you wouldn't have got a bit of a paper asking if you wanted a referendum on having a mayor —you didn't get a say. You wouldn't have got a bit of paper saying "who do you want to be mayor" —again: you don't get a say.

The fact that the council has a policy for petitions is something to cherish. The fact that they even let people from outside the city add their names shows that we do value those people who live out of town. But when it comes down to whom the council has to prioritise, it's the residents who vote for the councillors and mayors.

Everyone outside gets to make a whining sound, either in their own home, the BEP web site or their car sitting on the M32.

Is that fair? Maybe. Is it functional? Not for a region wide transport policy. But here's the problem: the N Somerset and S Gloucs councillors like their little kingdoms too much to share them.

Here we see Elf-King App Rees switching from demanding that the Clifton RPZ be removed screaming that George F is trying to dictate parking policy in Leigh Woods.

He loves being a small fish in a very small pond, and any attempt at having a broader region for  democratic governance as a threat.

Is S Gloucs any better? Well, they are very proud of the the fact that they are not quite Bristol, even to the extent of having a "Welcome to South Gloucestershire" partway along the Filton Road weekday traffic jam. Because Filton is, after all, distinct from its neighbours. But they do ask staff at the N Fringe of the city for their input on the latest bit of random roadworks.

What is not clear, though, is Why is Filton out of Bristol? . Same for those bits in N.E. Bristol. Emerson's Green, Rodway Common, etc. Part of the featureless hinterland of the city. And yet: you don't get a say —only the right to get angry about things happening in a city nearby.

Those pro-speed petitioners: do their opinions count? Not for 38% of them, no.

We've stated repeatedly we are Bristol's premier data-driven transport new outlet, compared with the evening post, which is driven by "what gets the most paper sales to our dying customer base" and "what generates the most page hits". Controversies involving parking, cyclists and speed zones hit all three.

Sadly, we don't have access to the BEP customer dataset or the details on commenters they extract from their linked-up google accounts. What we do have, however, is the python code needed to convert the published signatory list into a CSV file, with some extra flags to indicate whether or not the petitioner is in a 20 mph zone or not.

            20 mph ward  rest of BRS  CUBA    other 
Pro            920         305         116     201
Speeders      1552        3365        2289     705

As a graph, showing the numbers by area, things become more obvious

Of the speeders, 38% of them don't live in in Bristol. Which means they are, as far as Bristol elections are concerned, as relevant as residents of the Isle of Wight. They don't have a vote, all they have is a whine.

Looking at Bristol itself, we see a marked split between those people in wards with 20 MPH zones vs those which aren't.

Even though the pro-20 MPH petition is a fraction of the size of the speeder's one, it is not far off having 40% of the total petitioner count from the 20 MPH zones themselves.

This implies some things
  1. The people who get most worked about 20 MPH zones don't appear to live in them.
  2. Many of the people who get worked up about Bristol's 20 MPH zones don't even live in the city.
  3. They must live very unhappy lives.
  4. A lot of the people in the 20 zones seem pretty happy with the zones and their lives.
We'll collect some more data next week, and make up some new conclusions. Until then,  get out there and get some signatures for whichever petition you care about.

Monday, 24 August 2015

The 20 mph war on our council web site

There's now a battle of petitions up on the council web site

The scrappers: , "scrap the 20 mph limit and restore common sense",

We love the use of "common sense" in the title. "Common sense" means "obvious to the person making the statement". Yet, as we look throughout history, "common sense" meant the sun went round the earth. Galileo's Heliocentricity hypothesis was considered so heretical the common-sense regime at the time (Catholic Church) sentenced him to death. That's what common sense means: superstition over rational thought.

The retainers, "Keep and Extend 20mph limits"

These want the limits retained, extended, and maybe even enforced. We will call these "the people who believe Newton's equations about momentum and kinetic energy".

There we have it then, two factions: those who reject the physics of RTCs on the grounds of "common sense", and those who care about people walking and cycling round the city.

It will be interesting to watch the numbers. the flat-earthers have the support of the local paper, and a three month head start in the petition.

As of June August 23:

Flat earthers: 7421
Progressives: 1053

This is something we'll be keeping an eye on.

Saturday, 8 August 2015

Traffic Cameras: they don't shoot black americans

One of the recurrent themes in the UK press, with the Daily Mail-esque "Speed Cameras steal from motorists" story also recurring in the US,

Usually there are people quoted demanding instead real police, in real police cars, catching people "really" breaking traffic laws —by which presumably they mean "people other than themselves"

What doesn't get covered, though is how scary it is to be stopped by the US police compared to those in the UK. In the UK you get pulled over with some opening gambit like "is this your car, sir?", or "how much have you had to drink this evening?".

In contrast, in the US the lights go on so bright, with such a loud siren that you look up from your phone with a jerk, to see the police car filling your mirror and pull over in fright. Only here, the police officer (almost invariably a white man) walks over with their hand near their gun, ask you to wind down the window and then keep your hands visible, all the while standing a bit behind the door so that you are in front of them and its easier for them to shoot you than vice versa.

It is frightening, and you have to be so careful not do to anything not to make them overreact, and reach for the gun. And that's just as a white adult male in a nice car in a nice part of the US.

Now imagine you are an 18 year old black american being stopped at night. You know the police have a track record of shooting black americans even when pulled over for "minor traffic misdemeanours".  This is a country where failing to indicate as you change lanes has a death penalty.

You are going to be scared whenever you get pulled over, if you look at the statistics from places like Ferguson, you will be pulled over a lot more than white americans, and the is a small but tangible risk of you not getting out the stop alive.

In contrast
  1. Traffic cameras don't pick on drivers because of their skin colour or age/state of vehicle.
  2. Traffic cameras don't shoot black americans. Or any american, to come to it.

While in suburban americans may scream about unjust and unfair traffic cameras, you might find some locals with different opinions. Ask black americans kids whether they'd prefer being stopped by the police with a risk of being shot or having traffic violation fines sent in the post —you may find more support for the cameras. Now ask their parent, those parents who worry about their children going out for drives at night in the US, and they may give a very different answer.

Traffic Cameras: they don't shoot anyone

Visiting our strategic partners in Mountain View, California

We've stated before: with our strategic partners Google and Facebook we are building a PCSO state, one where people pay month for the privilege of being monitored, such as the how your Android phone reports in your movements 7x24.

We do of course have to visit our partners sporadically to brief them on developments, hence a short trip to the US. Expect some commentary as well as insights from Silicon Valley, which is now the hub of the future automobile. Even watching people gives us a profound vision of the futre

First, how to carry furniture in a "convertible"

The correct approach, clearly is to stick the chair in upside down, with someone on the passenger seat to keep an eye on it. The driver themselves gets some information on the chairs status: if they look in the wing mirror and see daylight then the chair has gone. If they hear over their music the sound of brakes and crash, they may also get an audible cue of the "chair loss event"

Until then, luggage transportation at work.

We just have one outstanding question though. We've seen them carrying a chair. What are they going to do with the Sofa?

Tuesday, 14 July 2015

Cyclists please dimount

We don't know what dimounting is, but given the incident near Bristol where a woman crashed her car while playing with an entertainment device, we have our suspicions

This is Temple Back East from Temple Back bridge heading for Temple Meads station from Old Market roundabout.

It could be a mis-spelled "cyclists dismount" sign, except there's no reason to dismount, not when there's the hatching to the left.

Dimounting, then, must mean something else. Our theory: riding a saddle designed to entertain your entertainable bits while on a ride.

Wednesday, 1 July 2015

Daylight running lights: the helmets of cars

It's been mandatory since 2011 for cars to have daylight running lights ("DRLs"). Is this a good thing? Or just it just up the arms race between motorcyclists, cars, pedestrians and cyclists?

For a change, there's actually some research on this topic, in the form of a 2008 study from the US government, "The Effectiveness of Daytime Running Lights For Passenger Vehicles". Bear in mind that the sample set of this study is of course US drivers, who are a lot more common than US ones to drive round at night without lights on. DRLs partially mitigate for this inattentiveness —or it may amplify it if drivers don't notice they have their lights off, on account of the DRLs illuminating in front of them.

The analysis evaluates the effects of daytime running lights (DRLs) against three types of target crashes: (1) two-passenger- vehicle crashes excluding rear-end crashes, (2) single-passenger-vehicle to pedestrians/cyclists crashes, and (3) single- passenger-vehicle to motorcycle crashes. Each crash type was examined at three crash severity levels – fatal, injury, and all severity. The basic approach is a control-comparison analysis of real-world crash involvements for DRL-equipped vehicles and non-DRL vehicles. Ratio of odds ratios were used to derive the DRL effects. A 95-percent confidence interval was used to infer statistically significant conclusions. The Fatality Analysis Reporting System and the State Data System were the crash data sources used for this analysis.
The analysis found that DRLs have no statistically significant overall effects on the three target crashes. When combining these three target crashes into one target crash, the DRL effects were also not statistically significant. When examined separately for passenger cars and light trucks/vans (LTVs), DRLs in LTVs significantly reduced LTVs’ involvements in the target two-vehicle crashes by 5.7 percent. However, the remaining DRL effects on these three target crashes were not statistically significant. Although not statistically significant, DRLs might have unintended consequences for pedestrians and motorcyclists. Particularly, the estimated negative effects for LTVs were relatively large and cannot be completely ignored.
The final two sentences are the highlight: from the survey done 8 years ago, it appears that daylight running lights may make it more dangerous for pedestrians and cyclists. And what are LTVs? That's pickups and SUVs.

The study was conducted by looking at crash statistics and seeing if those vehicles with DRLs were in crashes more or less. It wasn't a randomized sample (give people cars with DRLs on or off), which could skew the numbers (drivers of volvos are safer than drivers of ford mustangs, etc, older cars have worse brakes, etc.). Furthermore, as whether full lights were on or off wasn't recorded, the impact of DRLs at dawn or dusk can't be established.

Going in to the details, skip the maths unless you want to learn more about statistics., go to P4.10

based on the combined PC (Passenger Car) and LTV (Pickups and SUVs) results, DRLs seemed to have no overall effect on daytime target crashes.
See that? No statistically significant affects whatsoever. They are the helmets of cars: useless, yet designed to make you feel bad for not having them.

Now, P 4-14
For all crashes, again the estimates were not statistically significant. However, based on the combined State data, DRL effects for both PCs and LTVs were negative. Overall, DRLs seemed to increase Single-PV-to-PED/CYC crashes by 5.6 percent.

There you have it then. A feature which does nothing for overall safety rates, but which actually appears to increase risk for pedestrians and cyclists.

And on P 4-16, motorbikes
DRLs seemed to increase daytime Single-PV- to-Motorcycle crashes by 1.2 and 17.3 percent for PCs and LTVs, respectively. Overall, DRLs seemed to increase daytime Single-PV-to-Motorcycle crashes by 5.0 percent. None of these effects were statistically significant.
There you go then: daylight running lights appear to slightly increase the risk to vulnerable road users, while delivering no benefit whatsoever for the occupants of the car themselves.

Given this data: they do nothing for cars and endanger others, why offer it, and then why mandate it?

Offering it in cars could be assigned to a belief that it does make a difference (possibly even some unpublished data that it does).  Or, more cynically, because if possible purchasers ares somehow convinced that DRLs improve their safety, then they would buy that particular model of cars, possibly paying a premium. If you are a car manufacturer who discovered that spending £1 to ensure your car lights stayed on all the time could earn you £100 —you'd do it.

But why mandate it? That would remove all differentiation between vendors?

Some hypotheses(*)

  1. Politicians also mistakenly believe there is a safety benefit, and that by mandating it they can improve safety.
  2. Politicians don't care where it is beneficial or not, they just want to be seen to be doing something that they can take credit for and doesn't cost much.
  3. It is used as an excuse to avoid fundamental changes in road safety. Here the car manufacturers would be lobbying politicians. Unlike other features (ABS, Airbags) which actually cost money, DRLs are cheap to roll out. You'd push for them if the alternatives cost money.
Whatever the reason, its motorcyclists, pedestrians and cyclists who appear to lose out.

(*) There is also the theory that there is some other work that through some controlled A/B test shows that it does make a difference, and furthermore politicians have read and understood the details. This hypothesis is considered significantly unlikely.