A history of pedestrian crossings

A site hosted by one of our local anti-car traffic planners, Hamilton-Baillie Associates, leads us to this fascinating article, Crossing the Road in Britain, 1931-1976.

• The 1930 Road Traffic Act removed the 30 mph speed limit. It was re-instated in 1934 even though pedestrian deaths had fallen.
• When Belisha Beacons first came out there was a campaign against them, the captain gatso of its day, and people used to throw stones at them to break them. This idea of campaigning against zebra crossings appeals to us, though we do like the fact they act as short-stay parking for shoppers.
• In 1934 the Daily Telegraph was running its anti-pedestrian campaign then, calling for punishment for bad/careless/dangerous walking, while the Daily Mail was complaining that the government was picking on the motorist.
  
• A national road safety foundation, the NSFA, strongly funded by the motoring companies, resisted needless government interference -driving licenses, 30 mph limits- and instead focused on educating children and pedestrians.
• Pedestrian barriers were put in in London to stop pedestrians crossing except at approved points. We thought they were there to keep bicycles in the kerb and take away our paveparking, but clearly not.
• The Times was campaigning against Zebra crossings way back in 1954. We thought our Zebras belong in Zoos campaign was innovative, but not only were we merely reflecting the ongoing activities of Bristol's drivers, the war against zebra crossings has been going on for over fifty years.
• Light controlled junctions (first, "panda" crossings) to keep pedestrians out our way went in the early 1960s, ever since then slow, unfit people have been whining about not getting enough time. Move faster! Isn't walking meant to keep you fit! You put your foot down when we rev our engines and sound our horns -so why wait until then!
  
• These panda crossings were like zebra x-ings with a red light too, a "stop" and a "really-stop" for cars, and pedestrians had to wait for a really stop bit to pull out.
  
• Later pelican crossings had the stop/really stop bit, the flashing lights phase. Originally it meant that pedestrians could still cross, but now its been changed to cars can get in gear then go, like the red-amber phase on traffic lights
  
• It was a socialist government, and Barbara Castle, that introduced motorway speed limits and brethalyzers -the big anti-driver laws of the 1960s.
  

It's a fascinating twenty page read to see the struggle to resist anti-car pedestrians -historically the poor and working class, now the over-educated elitists. Our backers have been the people who get things doe -the House of Lords, the police, the German and Italian fascist goverments (Germany did introduce a "careless walking" fine as well as building the A-Bahn's). It's also interesting to see how the Daily Mail and Telegraph haven't suddenly jumped on the bandwagon needs of us, the British Motorist, they have been supporting us for as long as they've been saying Oswald Mosely and Enoch Powell should be listened to.

It's a shame to see so many attempts to rein in the pedestrians have failed -we never knew about red-painted kerbs at £20 spot fines for pedestrians, but apparently this was tried in central london in 1966. Bring it back, we say! All that has gone in from those time is the separation strategy, pedestrian overpasses and underpasses.

We shall cover them soon, as our fellow-travellers the Association of British Drivers are trying to bring them back to the Bristol centre. Now we have better historical understanding of their origin we can put them in their context.

On thing on the final page of the article:

Policy innovations seem to have been inspired not by casualty figures or public outcry about them, but by two main factors : popular hostility towards, confusion about, or lack of observance of previous pedestrian crossings or road safety campaigns ; and the desire not to impede traffic flow as congestion in town centres worsened.

We say: exactly. Zebra crossings impede traffic flow, as do other pedestrians running around our streets.

Two Wheeled Terrorists: official

There is a new paper out which argues, according to the Daily Telegraph, that Cyclists killed more people than the 7/7 bombers, on account of people switching from the tube/bus to bicycle. We were a bit doubtful about this, the null hypothesis being that the Telegraph reporter had made everything up, but no, it turns out that the alternate hypothesis, "the researcher made everything up" is in fact the correct one. As the paper author says to Moving Target, "cycling has been a greater hazard than terrorism and is responsible for far more deaths."

Reading the paper, it is clear that the author has confused correlated with causated (i.e. there may be other causes of any increase in cycling deaths/injuries than an increase in numbers; Olympic construction springs to mind), and relies on the same weak measurement of cycling traffic as everyone else does -some samplings of a few main roads that nobody rational cycles down. And as it doesn't take any health benefits into account, overestimates the damage of cycling. That is, technically, it's bollocks. But from the researcher's perspectivel it does achieve one wonderful goal: it gets read, it gets cited, they get more funding.

Discounting the "cyclists cause more deaths than terrorists" hypothesis as being invalid, we do note something that the author missed, namely that cyclists hold up tax payers, and if there were more cyclists on the road after 7/7, more of us tax payers got held up by bicycles. That is, the cyclists will have cost the country far more in car commuter hours than the 7/7 TfL shutdown ever did.

And that is where we think, unarguably, you can say that bicycles are a greater threat to Britain than the 7/7 bombers. Really. Yes, some insane idiots blew up a bus and some tube trains. But it was a bus, not a decent car, like a Mercedes. And it was in London. Whereas bicycles, they irritate everyone across every city in Britain. They are out there, every day, getting in the way, slowing us down, creating congestion where before there was none.

When will one party stand up and recognise these people for threatening our very way of life; our dream of a quiet commute in from the suburbs to our jobs in the financial services back offices, day in day out. Not just slowing us down, but stressing us out, getting us angry, shortening our very lives!

In this city, the council has sold us out. Only the conservative party is fighting the bicycle terrorists, and they aren't doing a good job of it.

There are three groups of people out there doing their best: the bus companies (FirstBus and Turner Bus), the taxi and minicabs, and the Clifton Downs committee. The bus and taxi people have to do it discretely, punishing each bike they see by cutting them up, by going past really close, by blocking the ASL -so that eventually the cyclists will see what we are trying to tell them -that cycling is dangerous and that they should stop it.

The Clifton Downs committee, they ban bicycles, especially kids bikes, to stop them getting addicted to this class-A drug and then going on to the roads when they get bigger.

But look, here we have one of these subversives standing on the grass, right next to a no-cycling sign -there it is, on the path, between the Mercedes WR08CPY and the double yellow lines.  And he's ignoring it. He's laughing at the sign as if it is some kind of joke.

It is not - the Clifton Downs committee are standing up to bicycles, the greatest threat our country faces.  Now we have the peer-reviewed literature to back up our claims.

Game Theory at Sussex Place junction

We are still seeking photos of the days when there was a mini-roundabout here, but until then we are blessed with this photograph of what the junction looked like pre-widening. Remember, at this time there was a bike lane and a pavement wide enough for a pedestrian to get past any parked cars. The improvements to the junction are to reduce pollution by helping traffic flow. Pedestrians and tax-dodging cyclists can use the back roads instead.

As to what is going on here, our Reporter "TJ", says

The picture was taken from Ashley Road and the sequence of events was as

follows:

• Lights are green for traffic coming off Ashley Road
• Lower Ashley Road was stationery and traffic from Ashley Road (white transit followed by green and black cars - hereafter Muppet Group A) moved forward onto the junction to avoid getting held all the way through another sequence.
• Lights change to green for traffic coming off Sussex Place
• Traffic moving from Sussex Place onto Lower Ashley Road (led by the yellow brakedown lorry) was unable to move forward much due to congestion on Lower Ashley Road and Muppet Group A.
• Traffic moving from Sussex Place onto Ashley Road got fed up with sitting there and started to pull out from the queue and drive down the wrong side of Sussex Place to get past the blockage. Quite a lot of this traffic was overtaking 10+ cars queueing to turn left onto Lower Ashley Road (i.e. driving a long way down the wrong side of the road).
• Lights change to green for traffic coming off Lower Ashley Road.
• Several of the cars coming down the wrong side of Sussex Place were still trying to cross the junction, including the grey sports car and the silver Nissan Micra in the picture but with more infront and behind (hereafter Muppet Group B).
• Traffic turning left from Lower Ashley Road into Ashley Road (led by lorry with white cab and blue body) is blocked by Muppet Group B.
• Traffic turning right from Lower Ashley Road into Sussex Place (led by silver people carrier) is blocked by Muppet Group A but would be blocked by Muppet Group B even if Muppet Group A had moved in the two or three minutes since they pulled into the middle of the junction.
• No-one can go anywhere until Muppet Groups A and B have managed to clear the junction.

I seem to remember that someone in Muppet Group B actually hooted at the traffic trying to go from Lower Ashley Road into Ashley Road under the green lights. They did manage to all clear the junction within a minute or two (the grey sports car on the right is just starting to move forward onto Ashley Road) but for a while it looked like being a really entertaining snarl up.

This is fascinating, as it is another classic example of real-world deadlock. In computing systems, a deadlock occurs when a number of entities are each blocked, waiting for the actions of the other entities. It can only occur if

1. There is mutual exclusion: here, only one vehicle can fit into the middle of the junction at a time, or into any of the junction exits.
   
2. A hold and wait condition exists: it is possible to claim one resource (the junction or an exit) before acquiring the other.
3. Resources cannot be taken by force. There is no easy way to remove a vehicle from the junction or an exit.
4. A circular wait exists: the chain of dependencies comes back to the original entity.

For more detail, there is a set of slides on the topic. While most people don't really care about such computing things, it is interesting to see it in the real world because of this:

• The self-interested action of each driver is to pull out into the junction, to make some progress when you get a green light, because when the light changes, the car at the front of the other junction will do exactly that, regardless of whether it can get out. As a result, the system grinds to a halt; it enters a failed state.
  

This is pretty important, because the whole idea of choosing the best option for yourself regardless of the decision the others make is the whole foundation of Game Theory. And in Sussex Place, the Nash Equilibrium appears to result in the loss of traffic flow. (Yes, that is a university lecture, but its a political science one and doesn't have much maths in it)

So, why is that important? Because Game Theory was the underlying political science/mathematics of the cold war. And John Nash, the mathematician behind it. These are the equations you would use when planning a conflict escalation policy that starts off with tanks in Berlin or Vietnam, and ends with an exchange of strategic armaments in ballistic missiles over the Arctic Circle, and hence the end of humanity -the big Failed State.

The politicians, the soldiers, sat their with their maps, their tables, their graphs, got the mathematicians in and game up with plans that during the cold war came pretty close to that condition on a couple of occasions, but everyone always backed off. For which we all have to be very, very grateful.

Comparing the Cold War to Sussex Place then, we have to pretty glad that those people trying to drive across Bristol weren't involved in planning or managing the conflict, as we wouldn't have stood a chance of getting through it alive.

The Watchman has arrived

When discussing what looked like a bus lane camera, James Barlow, author of Bristol's second best web site, noted that it was a watchman. More research was called for.

The watchman series of cameras include ANPR, 3G data modem, high-resolution video camera and a local hard disk drive capable of storing number plates (2 million, they say), and video shorts. If you are speeding, they actually get a video. They can also do bus-lane violation checking, which may worry the Peugeot 307 seen doing exactly that. To verify that a car shouldn't be in there it is not enough to say "is it a car"; you need to check it isn't a taxi or minicab. The Association of British Drivers have a list of proposed allowed vehicles, including lifeboat crews. Before sending a ticket to the '307 driver, the council will have to verify that the drivers/passengers were not on a lifeboat callout, on their way to Bristol docks.

The Watchman is not designed for simple speed-traps; it is a monitoring tool. It looks like it may be able to measure traffic numbers and all vehicle speeds, which could be used for datamining. As it is not currently part of the national ANPR network used to monitor and log all motorway traffic "for homeland security", this may be data we could get hold of.

The camera comes with software that sends polite notes warning drivers of their behaviour; warning notes. Their purpose is to remind without penalising. If you get a ticket, you have to pay, the insurance company ups their charges, and you may get disqualified. If you get a polite note, you can ignore it, unless eventually you start to get tickets.

Will it work? The device itself can find out. Start by monitoring peak traffic speeds before the notes begin being sent out, and their registration numbers. Then start sending notes out, and see if peak speeding speeds drop -or if the previously noted vehicles get seen repeatedly. Again, this could be a simple datamining exercise.

The sales brochure implies the cameras can be set to look for specific vehicles; download a number in and the camera will send an alert out when a specific car is seen. With a hard disk, you've got room to store a lot of numbers to search through.

Security wise, the over-sturdy mounting point is probably designed to resist a truck driving into them and getting away. You can still drive a truck into them, but it will leave noticeable damage on your vehicle. The manufacturers are proud of their security measures, though they also give away the windows software needed to connect to the cameras. The attack points for this devices are no longer the yellow box, they are the network. The camera will have a mobile phone number and a password to guess; the computers used to access it will have to stay up to date with Windows monthly OS patches or they become a target in their own right. That's the problem with networked applications: you think your device has just discovered the Internet, but in reality, the Internet has just discovered your device.

Tampering with Speed Limiters

Some researchers up in Leeds have published a study of GPS-speed limiting cars.

The central cycling groups are in favour of it -because the idea of cars not speeding appeals- and the "unionists" -the Association of British Drivers and their anti-speed-camera allies are against it.

Bristol Traffic leaves it up to individual contributors to have their own opinions. But this one, the Computer Scientist in the group, is against it on software engineering grounds:

It is one thing to have SatNav give you hints as to where to drive -hints you should consider but not follow blindly, another to be relying on GPS and accurate mapping data to control your vehicle

The Leeds study took volunteers and explored how voluntary and mandatory speed limiting worked, then interviewed various people to see what they felt of the idea. What they did not attempt to do was impose speed limiting systems on unwilling participants, people who wanted to drive fast. Doing so would not only show how acceptable the idea was to the country at large, it would show how willing people were to subvert the system. A realistic study would therefore instrument a city's taxi/minicab fleet (I can think of a city), or all drivers convicted of speeding coming off a driving ban.

As it is, the closest we have to speed limiting infrastructure we have today are the tachographs in lorries, that monitor speed and working hours. Which is why Ross Anderson's wonderful book Security Engineering has a section on subverting tachographs, right between Banking and ATM security and locking down Nuclear Command and Control Systems so that high-energy physics events only take place with senior management approval.

Trying to limit vehicle speeds from an bit of in-car electronics and GPS is as workable as the film companies trying to restrict DVD players to specific regions so they can charge price differentials on different continents (result: multiregion players cost a 10 pound premium). It's as workable as the games console companies trying to stop you hacking into the controller so you can play downloaded games burned onto your own disks. Results: modified firmware chips are widely available. These consoles are not easy to hack, either; it took someone at MIT three weeks to 0wn the Xbox. If there is money to be made from subverting something in your possession, be it a games console, a DVD player or a tachograph, then someone will do it. And if the hack is a software one, then it usually scales well. Only one person will need access to the Scanning/Tunelling Electron Microscope, the rest just pay for the results and some modified firmware.

Imagine that three years from now, every car comes fitted with mandatory speed-limiters driven by GPS. How would you attack it?

Attack one: lie about your location. Civilian GPS isn't secure; it isn't signed and anyone could generate spoof satellites. An in -car pocket GPS Jammer would generate signals telling the satnav unit that you were in France or Germany and could drive as fast as you like. This is a good attack as when the jammer is off: it doesn't show. When the speed limiter is checked in the MOT, all would appear well.

Attack two: firmware hacking. All embedded computers with upgradeable software can be subverted with new firmware. There may be some checks on the firmware -that it is digitally signed by someone trusted-; these need to be subverted first. If you can roll back to the legit firmware during the MOT tests, nobody will know.

Attack three: hardware patching. The common games console attack. Shows up in a physical audit.

Attack four: don't update the maps. Assume that every year, speed limits come down. There is no benefit, then, in updating your maps. Snap the link to the GSM modem, or refuse to pay the 10 pounds/year for updates. If the MOT checks that you are up to date, someone needs to record the previous year's update, and after the MOT, you replay the older map into the SatNav.

Attack five, and this is the fun one: generate fake maps. Create one that says the max speed for the country is 120 mph. Install it in your own machine, sell it to others. At this point the security experts are going to say "ah but our system will only download signed maps from a trusted provider". Which may be true, but rests on certain assumptions about the security of things like HTTPS, those web sites with the green bar in the browser window, which tell you that that bank site really is who they say they are, and not some russian Phishing site. On the same day that the UK government published their paper on SatNav-based speed control, a group of Dutch hackers published a lovely paper on how to subvert HTTPS by creating a fake certification authority. It's a fairly complex paper and hard to understand, the good news being none of us need to know the details. What is important is that people like Ben Laurie, key developer of the OpenSSL stack and Apache SSL module is scared. Because right now, this week, we can't trust HTTPS sites to be who they say they are. There are very serious implications for the web for this, but they would also impact things like satnav based GPS. If I could make a fake map that removed all speed limits from cars sold after 2012, how much would it be worth?

If SatNav-based-speed limiting is flawed, what to do? Well, why not charge a bit of road tax based on peak vehicle speed? Or just speed limit all cars to 100 miles an hour, more than enough for UK overtakes and driving -and to get you to the French Alps when needed- but removing demand for big-engined cars that waste petrol at normal speeds. Or rely on the ANPR-instrumented motorways to catch speeding cars, and similar infrastructure in-city. Because you are going to need such cameras up to keep an eye on the older cars, the cars from the rest of europe, and to detect people who have just paid for my high-speed map of the country. There are lots of options that don't rely on tamper-proof hardware being embedded in cars with tamper-proof maps and reliable GPS constellation data received in real-time. It would be one of those things like biometric ID cards: a expensive way to not solve the underlying problems.

Engineeering Terminology

Having met the odd traffic planner/civil engineer in the past year, one problem is that they have a technical language to describe things, a language they use to communicate with their peers -but also to exclude those who are not educated in civil engineering. What to do? Josh Hart is going for the "learn the language" approach, by studying at UWE.

The rest of us don't have the time to do that. Instead I'm guest lecturing at a local university on computing topics, which is going to provide the answer. Instead of wasting time learning civil engineering concepts and terms, take software engineering/computer science terminology and apply it to traffic. The advantage of that is that you don't need to understand the details, to be able to handle the reply when you say "The O(1) scheduling algorithm delivers fairness but under 80% saturation the router tends to drop packets on the floor". Because if you are saying it to the traffic planners, they don't understand either. But it scares them. Which is important, as from the early findings, there isn't much in the way of science in traffic management; there's no experimentation. Just some simulation programs written in the early eighties based on inadequate data. That's a belief-driven approach, not the evidence-driven one that is the basis for sciences.


If it were a proper science, it would be data driven, from repeatable experiments. For example, before proposing replacing zebra crossings on Blackboy Hill with puffin crossings, they'd check to see if pedestrians would stop on the red light,. Once they knew what number of people would ignore the light, include that in their simulations and risk analysis. Then they'd stick up some temporary lights to see what happens to the congestion, before dropping a few hundred thousand pounds on it.

Anyway. Henceforth, this blog will sometimes introduce computing terminology for the reader. Enough to intimidate the odd traffic planning consultant. Especially once we start collecting the data they don't seem to have. First up: deadlock.

Datamining the school run

On some initial surveys, Clifton High appeared to be free of parents exploiting the school-keep-clear section. But it was just their school starts early, at 0830.

Here, on Oct 8, at 08:39, One car doing a dropoff in the defacto-dropoff-zone: WU56LUD

Here, on Oct 9, at 08:28, a car doing a dropoff in the defacto-dropoff-zone: WU56LUD

This car is are now, as they say, "in the database". Not some toy little local government database running on a ropy server in an undercooled attic. Not some secret central goverment server farm somewhere of car number plates -no, they are in a bigger database: the Web. In one of Google's datacentres.

Photos are uploaded to Picasa, running on the Google File System. That also hosts the blog, routing the click log back into GFS for Google Analytics to analyse the visitors, creating stats that get stored in BigTable. All words in the blog, including registration numbers get picked up in their PageRank scans, probably implemented as a big MapReduce job, with the results again stored in GFS and BigTable. Which is why, a few hours after this posting, a search for the word will not return "Your search - WU56LUD - did not match any documents.", as it does now, it will return this page -and any others we add later.

That's our database. A combination of photo, tags and text marks up all cars whose driving/parking skills are felt to be significantly entertaining to merit attention, and then, when the time comes to visit the particular schools, we just retrieve all entries tagged with that school, paste the photos into powerpoint, and we have the list of repeat offenders we expect them to deal with.

Which is why it is important to thank people for their contributions. That's the photographers, but also the subject. Thank them, after they've had their car/bus/van snapped, because without their actions, we wouldn't have anything interesting to write up, and the database would be that much less useful. And Google's BigTable would have less number plates in its columns.

Muller Road: 20K cars/day

One of the interesting facts to come out of Josh Hart's Bristol street study is that 20,000 cars per day go along it. Morning and evening it is congested going to and from the M32; cars coming from Lockleaze cut through garage-alleys to spend less time stuck at the Shaldon Road junction

And so get into the queue leading up to the M32 that much faster.


It's a tough road to walk or cycle across; you need to wait at the lights and factor in to the light schedule the fact that cars coming off the m-way are slow to react to red lights. In the Bristol Cycling Campaign, the Muller Road/Shaldon Road junction is viewed as positively lethal, the fact that 'safe route to school' improvements made it even more dangerous should have been a warning sign about threat that a "cycle city" bid could present.

One thing that Josh's study didn't do is ask where do these cars go to? Where are they coming from? Assuming they are coming into the city on the M32, not using the ring road exit but pulling off before getting stuck in the traffic jams by the M32 junctions further into town, these cars are heading to North West bristol, but not the North Fringe. So where do they go?

Streets and Neighbours

Joshua Hart has done an interesting study in Bristol, which shows that people who live in streets with more traffic visit their neighbours less.


This is interesting, but what cannot directly say is "living on a busy street makes you friendless". Why? Because one possible hypothesis is that friendless people choose to live on busy roads. Houses on/by busy roads cost less, they are often divided into flats and may have higher turnover. And it is that turnover that may effect things. What would be interesting would be take one of the roads in the study -such as Muller Road- block it off to car traffic for a month, and see if that leads to increased neighbourliness. Having seen the consequences of Cotham Brow being closed to traffic, and how much quieter the whole area became, the results may be surprising.

Another possible hypothesis -though it seems even more unlikely is this: if a street forms a strong community, does its traffic decrease? mu

Traffic: a book. But will it have photos?

There's an article up on Salon about a new book, Traffic. It looks at the psychology behind driving, with some interesting quotes: signaling is revealing your intentions to the enemy.

Maybe, but that assumes you are signalling a wish to change lanes, rather than providing immediate warning of your intent to change lanes regardless of the presence of another vehicle, that being French-style signalling rules. In fact, despite all the claims that Boston is a hard place to drive, it isn't, not by European standards.

What is interesting in Boston is parking. There are parking lots to park in all day, but they are expensive. The alternative is to park where you aren't allowed to, and risk being ticketed. It all comes down to some simple equations. If P(ticketed) is the probability from 0 to 1 of being getting a parking ticket, and that happens one day in five then P(ticketed) = 0.2. If the cost of a ticket, is say , $50, then the daily parking costs are $50 x 0.2, or $10; less than a parking lots' cost of $20. It's cheaper to park illegally and get ticketed sometimes. So the drivers do.


In Bristol, the equation is even simpler. Outside the pay-to-park inner core, P(ticketed) is effectively zero, so the daily cost of parking where you want is 0. Whereas the cost of using a car park isn't, nor is the cost of using FirstBus. So what do people do? They drive close to the centre and park where they seem to be able to park without being ticketed. Because no other action would make sense.