Wednesday 25 September 2013

Van in disguise

An important piece of advice to van drivers who wish to demonstrate their rightful place on the road is that it is sometimes necessary to do this incognito if you do not have the time to enjoy a joke and pint with the friendly local constabulary.

If you do not have access to a plain white van (and you call yourself a van driver?), a hired vehicle is the perfect substitute, allowing you to perplex any cyclist who thinks they have the right to safe passage as they'll never be able to tell where you work.

Here in the video we see that the driver of the hired Thrifty van HX53JXR demonstrates the technique with perfection as they pull into the local DPD depot on St Philips Road.

Friday 20 September 2013

Peter Abraham: show us the 20 mph road rage data

One goal of Bristol Traffic is to create datasets on how people get round bristol. It had been to create a  ubiquitous mass surveillance police state -but it turns out Google have done that and then pass on the details to the NSA. So a focus on local issues for us.

While covering the Down's refusal to adopt 20 mph speed limits,we picked up on a statement by Cllr Peter Abraham:
A 20 mph limit might be appropriate for some streets, but I think it will cause road rage incidents and a lot of frustration for motorists on The Downs."

This assertion, road rage causes frustration is news to us. We've been against 20mph for a long time, not because it increases the likelihood of us getting out a cricket bat and bashing in the windows of the Citron Dyane doing 19 mph in front of us, but because it means it will take longer for us to get round the city.

Now  presumably road-range incidents need >1 vehicle, so driving at 20 mph when it is quiet isn't going to cause you to jump out the car, get out the old cricket bat and bash in your own windscreen. The probability of a road rage incident must not only be a function of the driver, the road and the effective limit, but of the speed of the vehicle in front:

For any driver, Dn the probability equation becomes one of:

P(road-rage(Dn, road)) = fn(driver, road, limit, velocity(Dn), velocity(Dn-1))

For an entire road over a day, with K drivers, the probability of a road-rage event is

Sum(Dn=1..K) P(road-rage(Dn))

To predict that road-rage frequency, we need to know the value of the function fn(driver, road, limit, velocity(Dn); we can derive the rest from there.

It is critical we get the numbers to derive this, as well as understand where it is a discrete function such that it returns 0 for all speed limits >20, or if some drivers are capable of going over the edge at 30 mph, 40 mph, etc.

Nobody appears to have this data other thal Cllr Abraham, who is shaping city speed limits based on his private dataset.

It's more important than the downs too. If the road-rage probability gets higher whenever the speed of the vehicle in front is less than 20 mph,  velocity(Dn-1)<20), then anything in our city which forces people to drive below 20 mph is going to create incidents.

That means we have to ban bicycles from all city streets where a car could be held up behind them.

For example, Hampton Road, redland. There would be a nice fast 30 mph stretch between two traffic jams, yet WV06WML is trapped in traffic between two bicycles. He only just manages to clear one and so sprint up the hill to the St Michael's Hill roundabout traffic jam by aggressively overtaking it and swinging in before hitting the oncoming cyclist.

if there were no cyclists here this incident would not have arisen. Admittedly, the journey time of the car would be the same -it's a different function, one that depends on the congestion of junctions, so is a function of all road users in the city at a specific time, not just the velocity of the vehicle in front.  But we aren't worried about that: we are worried about road rage.

Peter Abraham appears to be the only person in a position of authority in Bristol with the confidence to assert that 20 mph limits increase road rage. He needs to publish this data, not just so that we can resist the rollout of the 20 mph zones, but to back our campaign to ban bicycles from the streets.

But will he provide it? We asked last week for that data:

---------- Forwarded message ----------
From: Bristol  Traffic <bristol.traffic at>
Date: 13 September 2013 09:17
Subject: Press Query about speed limits in the downs


The Bristol Traffic Project is -as you may know -one of Bristol's premier online reporting sites, focusing purely on transport.

While we are often regarded as some form of shallow spoof, we consider ourselves an evidence-driven organisation: we use photographs and videos to defend our statements, while our coverages of game theory as applied to Bristol's streets include articles that have been cited by such luminaries as Tom Vanderbilt, author of the book, Traffic.

Accordingly, we'd like to follow up our coverage on the proposals for 20 mph limits in the downs, with a query for some data to back up the decision of the committee to retain a 30 mph limit.

One statement you have apparently made to the evening post was that a 20mph limit is inappropriate for the downs: I think it will cause road rage incidents and a lot of frustration for motorists on The Downs."

Here are our questions

1. Do you have any defensible data that demonstrates that 20 mph limits lead to road rage?

2.  London's Royal Parks all have 20 mph limits. What is unique to Bristol's parks, or its residents, that mean that having a 20 mph limit in an urban park is something which they are unable to cope with?

3. Did the downs committee consider how the retention of a 30 mph limit will continue to make cycling on these roads intimidating, especially for families -and that either this would be at odds with the management plan's stated goal of encouraging cycling -and likely to push the cyclists, especially family groups, onto cycling on the footpaths instead?

We await your responses


Chief Data Scientist,
Bristol Traffic Project

---------- Forwarded message ----------

To date we have heard nothing, even though a week has passed. Presumably Cllr Abraham is a busy man, but even so we are concerned that this data -which would be invaluable to the debate about cycling as well as 20 mph limits is being held back.

We shall have to follow this up with another request.

Thursday 19 September 2013

Anything Clifton can do, Stokes Croft can do better

Our Whiteladies road texting coverage shows that 1 car per traffic light cycle is on the phone. Well, if that's clifton and the commuters from the ""20 mph means road rage" suburbs over the downs, Stokes Croft will have to do better -won't it.

Here then is a video at about 16:50 on a weekday evening. The tax dodger is cycling up Nugent Hill, while some children are returning home in the other direction. Given the 15% gradient, that family is earning its school dinners.

Then, down to Arley Hill to count the no. of vehicles phoning or texting in the traffic jam. Arley Hill cuts through from Cotham to Cheltenham Road, where, if you tuck into the bus lane and then go up to turn left towards Ashley Road, gets you to the M32 at the St Pauls Roundabout -without having to go to the bearpit roundabout or nearby. This makes it a nice little route from Redland and Clifton to the M32 at peak hours -too nice, and too widely known.

If you look, there are a set of different actions taking place in the vehicles
  1. despair. driver holding onto the handle above the door, disbelieving that it can take so long. Tourist?
  2. phone: talk, text or facebook.
  3. eat.  Not just junk food either -a couple of people are eating prepared meals from plastic containers. These are locals who know it takes 10-15 minutes to traverse Arley hill at peak hours.
  4. enjoy the music. Only a couple of people are doing this -but they seem happy.

It comes out to seven vehicles: P217UWS, HG10AKP, KM59KML, FA04VZL, G869UAM, KF54EHH, BF08DJP.

Fluke! the Cliftonians cry! Pure Chance!

Possibly. Lets try that again, shall we?

Heres the next video, from the bottom and back up again.

There's been enough of an interval that the cars at the tail of the previous survey are now at the front: KF54EHH, texting at the end of the last video, is now the second car in line, still texting happily. Now the car behind, MF56VJC, has joined in.

Carrying on up, we encounter the van BF05VZT,, a large grey van WV13YHA on the phone, and then the white BMW WN13CCE with the driver texting.

The driver in the "don't cook just eat" car is hand-rolling a cigarette -false alarm.

After the speed bump comes the renault megane HV03WNR, then, after a small gap, the Honda Civic WJ06ZBN with its driver speaking on his phone. Finally, just after the RAC van comes white van W9MWM. At this point the vehicles are moving, so the driver here is left with a problem: how to text while driving over a speed bump.

The solution is obvious, put the phone onto the steering wheel and hold the wheel while you text with your thumbs.

After that: no more. Note that the normal scapegoats -taxis and minicabs- are not joining in. They work in the car, there's no need for them to text ahead saying "I am stuck in the traffic jam that stretches from Arley Hill to M32 and which appears here every evening".

Looking at the numbers from that last video and comparing with Clifton, in that initial stretch from Nugent Hill to the lights, there are 13 cars, of which five are on the phone: one speaking, four texting.

Thats 38% of our sample set. Discount the speaking and focus on texting: 30%.

Those are numbers clifton doesn't even come close to. Here we have a line of traffic and over one driver in three is on the phone.

Clifton? DNC: Did Not Compete.

Wednesday 18 September 2013

Does car parking encourage local shopping?

One of the "Pickles war on the war on motorists" issues is that the lack of free parking is destroying the high street. An interesting assertion, but is it backed with real data? Well, we like our data over opinions, especially when the opinions come from politicians, national or local, which aren't backed up by any evidence.

Here is whiteladies road on a weekday, from Clifton Down shopping centre  up to Blackboy Hill, or more precisely the Port of Call pub.

Some things to observe.

  1. 0:00 starts at clifton down, where a mid-size Sainsbury's provides groceries and beers.
  2. The first 1:15 of the 2:30 video contains a stretch with vast amounts of short stay parking for shoppers. With the roll out of the bus lanes, the commuter parking here is now gone.
  3. The first 1:15 of the 2:30 video contains many vacant shops. Two camera shops -killed by digital cameras eliminating the printing business, and Amazon. One bookshop: killed by Amazon. A bottoms-up off license. Some clubs which went away when "the strip" fell out of fashion.
  4. The upper half of the video contains lots of shops -even though the parking spaces there are all full. It includes esoteric shops: kitchens, ellis brigham, artists supplies premium things: a fish shops, a cheese-vendor, and everyday things. 
The implication here is not that a lack of parking kills shopping, but that online trading and digital devices has destroyed the business models of some shops, trends in nightlife (and the cash to party) others. The 2008 banker-created recession has probably been more destructive than anti-car policies in this road.

Another issue may be that the Sainsbury's sucks up all the daily shopping cash, leaving only outdoor coffee shops nearby and a post office/chemist. The upper section of the hill keeps going due to a large local resident population with enough money to buy things, and the fact it contains the last off licenses, pubs and chip shops before the downs, or more precisely the student halls of residence on the other side of the downs.

(footnote: one of main camera of this project, a panasonic TZ27, came from Jacob's cameras which was at 0:54. London Camera Exchange in central Bristol is still surviving, showing that some of the more specialist camera shops are surviving -even though parking there is worse)

Monday 16 September 2013

Whiteladies Road Texting: DG54DFV joins the dataset

Last week's Suspension Bridge visit showed that only 1 car in 100 in that traffic jam was texting. Maybe our Whiteladies Road "one car in 6" dataset was a fluke?

More study is needed, so here is another quick visit

This time, DG54DFV is the vehicle with a driver texting. We should start collecting gender statistics. Today: female.

Maybe there is something to do with the fact that this is often the journey into town, the inbound route, which encourages texting. We should stop and ask people about why they are texting or checking facebook to understand this. Or perhaps delegate this task to Avon and Somerset Police

Thursday 12 September 2013

Reminder: We are a data driven organisation that understands how things work

Some people -mistakenly consider us to be some kind of spoof, whereas in fact we are a documentary that has built up a weakly-defensible dataset of the city's transport issues.We also include topics like queue theory, game theory and the like to analyse that data.

This is why we despair when the legacy mass media publish articles that lack both real data and the fundamental understanding behind it

Now, Queue theory, Erlang's core concept: A queue happens when the egress rate of a channel is lower than the ingress rate.

In less technical terms "you get a queue if less things are leaving something than entering". It doesn't matter how big a bucket is, if more watering is pouring into it than is leaving from a hole in the bottom -eventually it will overflow

In evening post commenter terms "there's no point making something two lanes wide if it has to go down to one lane wide a bit further on". The bottleneck is the one-lane bit wide, not the two lane stretch.

We know this is hard to grasp, which is why people are still complaining about the Portway bus lane. Evening Post Commenters: the bottlenecks are the narrow bits beyond the suspension bridge and Anchor Road -removing the bus lane will not increase your journey time by car at all.

Alternatively: it is futile to remove a bus lane in the name of congestion, if there's a single-lane road later on. You are wasting your life on something that will not deliver the benefits you expect. You may argue against this using the term "common sense" -but that is why building things from bridges to computer networks rely on people called "engineers" trained in something called "mathematics". Common sense doesn't cut it when you actually want something to work.

The Evening Post reporters need to pick this up too.

As today there is an article, Traffic lights on Blackboy Hill 'are cause of the congestion'.

A BRISTOL campaigner claims a set of traffic lights at a busy junction cause more congestion than they solve – and should be ripped out.
Simon Brookes, who led a campaign for the removal of a controversial bus lane in Westbury Road, is now calling for the removal of the lights at the top of Blackboy Hill.
We aren't sure what "campaigner" means here. Presumably it means "someone who doesn't understand queue theory but likes to get their face in the regional press"

He conducted a survey and claims that the lights held up lots of buses.
Mr Brookes carried out another survey yesterday between 9am and 10am. He said he witnessed 89 changes of the lights and during that time, only two buses went through on green. But the number of buses going uphill and held up on a red was 26.
We are surprised that Mr Brooks has now started caring about buses. Because if you are trying to get bus lanes removed on the approach to Whiteladies Road, suddenly caring about their performance in Whiteladies Road itself seems somewhat hypocritical -unless you are simply pretending to care.

Furthermore, if you are going to do a survey on congestion -why do it outside the rush hour. Do it at 08:30 at peak commute and school runs. Doing it after 9am is like saying the M32 doesn't get congested because you drove up it on a sunday morning.

Bad data, failure to root cause analysis and then pretending to care about public transport. We don't do any of these.

Mind you, Mr Brooks' pretence to care about buses doesn't make it through the article:

He will also be calling for a cycle lane to be removed from Westbury Park, where it meets with North Road.
He said the lane was not used by cyclists and simply added to traffic congestion.
Mr Brookes also wants to see the removal of the remaining stretch of bus lane from Westbury Park.

Sorry, but the congestion has other causes. It may seem frustrating to be stuck in a car watching bike lanes and bus lanes that are empty most of the time, but that is because they are working. The buses are not being held up until they merge with the cars on Whiteladies road; the bicycles not held up at all, mostly.

Here then is our dataset: a video from  "wheels on the bike" counting the entire set of vehicles on Whiteladies Road, from the top to the triangle, in 1:45.

Most of Whiteladies road is one lane wide. That is the bottleneck -the carrying capacity of the road. Arguing about bus lanes  up the hill or even switching times of traffic lights is irrelevant when there is a lane traffic jam from Park Row and Park Street stretching all the way up to the Downs.

This is why appearing on papers demanding for things to be removed because they "cause congestion" is dangerous. Someone may one day see this video and say "maybe there are other issues". We know that -it's the surburbanites driving into town. Simon Brookes should recognise this, and keep his mouth shut.

The Downs Committee joins the Bikelash!

Attached to Clifton are "the downs". You can recognise it by the way that all paths on the park have a big "No Cycling" sign -usually near some parked cars

The nominal reason they have the no cycling sign is to stop pedestrians and parked cars being damaged by cyclists.

In high summer, the Downs committee allows the Zoo (in exchange for money, obviously), to let visitors park on the downs, and bill the visitors for doing so.

In 2010 proposals to provide a park and ride alternative, were, rightfully, rejected.

It's quite clear what the Downs Committee wants. Nobody cycling on the pavement, people driving to the downs and parking on the grass.

Even so, council plans threaten it -and this week it is with a shocking proposal to make the speed limit in the park 20 mph!

Fortunately, the committee has come out and rejected it.

PLANS to bring in a 20mph speed limit on roads around The Downs have been opposed by the committee responsible for the open space.

The Downs Committee – made up of councillors and representatives from the Merchant Venturers – considered the proposals at their meeting yesterdayand voted against them by four votes to two, with one abstention.
Councillor Peter Abraham said: "I feel very strongly about this and I think we should oppose the 20mph limit being brought in on roads around the Downs."

Merchant Venturer Andrew Densham said he had attempted driving along the stretch at 20mph before the meeting and was greeted by flashing lights from fellow motorists.

"It is almost impossible to do," he said. "Going 20mph is absurd on most of those roads.

"I think the consequences of it would be more dangerous."

Fellow Merchant Venturer Anthony Brown said: "The traffic sub-committee asked what the experience had been on Ladies Mile and was told the average speed was 26mph and there are no major problems.

"If the speed limit is reduced people would do 20,16,18 and people would want to overtake. It was our view that it could be more dangerous."

there we have it then. Total opposition to the proposals based on a single experiment of driving round at 20 mph, once, and noticing cars got upset.

We can expect the cycling campaigners to be a bit put out by this
  1. Flat out refusal to provide safe alternatives to Ladies Mile or Sea Wall/ice cream van routes for bicycles
  2. Flat out refusal to consider lower speed limits that would benefit cyclists or even pedestrians trying to cross the road.
The tax-dodgers should not be surprised by this.

Cllr Peter Abraham is the councillor for Stoke Bishop, whose residents have to drive over the downs to get anywhere. It's bad enough that the RPZ is going to remove a lot of parking opportunities, now they will be forced to drive a little bit slower.

As he said earlier.  :
I would much rather see the 30mph limit, which was only recently introduced, rigidly enforced. A 20 mph limit might be appropriate for some streets, but I think it will cause road rage incidents and a lot of frustration for motorists on The Downs."
See: the council has already forced the speed limit down from 60 mph to 30 only ten years ago, and it is hard enough for his electorate to handle

Lowering the speed limit in one of Bristol's main parks from 30 mph to 20 mph would only increase road rage, and, by encouraging people to walk and cycle round the park, increase problems!

This is why we support the actions of the Downs Committee. We also appreciate that many of the committee members are from the Society of Merchant Venturers. It is precisely because these people are chosen without democratic oversight that they are able to resist petty popularist policies like making parks safer for pedestrians and cyclists! Only they can represent the true voice of the evening post commenters!

Wednesday 4 September 2013

Better texting data: only 1 driver in 100 does it

Our morning surveys show that about 1 in 5 drivers stopped at a light is texing or phoning. Pretty damning -but there could be selection bias. The lights stop the drivers who aren't aggressive -possibly because they are on the phone. And its one route, morning only.

More data is needed.

Here then is a short video of the route from Ashton Court to Clifton, initially showing a line of stationary traffic on the A369 (Portishead and M5 Gordano Services exit), heading down to town. Ignore them: our dataset is the line of vehicles heading to the junction from the Clifton Suspension Bridge. It's great for a survey: a row of stationary vehicles, easy to measure from the other side of the road, and because of the toll, many people have their window down.

Count the cars, and see if you can spot the one texting

For the inattentive, it's the Audi 1:88, where both driver and passenger are tapping away on their smartphones. That's the car with the custom number plate RJZ1066, to show how important they really are.

Sadly, even though they are important, they are stuck behind 70+ other vehicles driven by people who also think that they are important, so the Audi driver has to text ahead and perhaps add updates on facebook. It is selfish commuters who are holding up the important people from getting home from Clifton.

What's important is that the new data shows that the claims that 1 driver in 5 is texting at lights is clearly false -at least here, on a weekday evening.