101 uses for a nearly dead Ginkgo tree

We've noticed 4X4 drivers often have to deal with the problem of street trees when they park off-road in Bristol. Even in RPZs. Even in 20 MPH zones. Even near schools.

Fortunately many of these trees are now stumps and some of the stumps have been there so long that they are rotting into the ground and the removal can be accelerated by a little nudge. In time they will be tarmaced over but in the meantime the tree pits provide a little offroading experience.

 

Unfortunately some of the street trees that are planted, such as London Plane trees, grow quite quickly and rapidly provide the amenity and canopy cover that "environmentalists" love to promote at the expense of proper off-road pavement parking.  

 

However... Not the humble Ginkgo tree. It's a relic of the age of the Dinosaurs (and a conifer to boot - don't let those weird leaves and the fact it sheds them in winter fool you). 

 

This particular specimen has hung between life and death and remained the size it was planted for about a decade. 

The question as to whether urban trees have any purpose is maybe too philosophical for this blog. But in a very practical sense this particular tree has finally found its purpose and meaning in life in modern day 20 MPH Bristol.  

 

It is providing security for a traffic counting and speed measuring device.

Speeds on 20 MPH Redland Road are, of course, consistently well above 20MPH, so this tree may finally contribute in some small way to the urban fabric by helping Bristol City Council to calm the traffic down this very steep hill where even cyclists regularly exceed 20MPH whilst car, van and lorry drivers overtake them with gay abandon, because they Must Get In Front.

 

We are struggling to come up with a single other use for this or any other Ginkgo so finding a further 100 uses may be a tall order.

20 mph! for the whole city! Disaster!

Terrible news reaches us: the council has voted in 20mph speed limits on all residential roads in the inner city.

This is heartbreaking. It doesn't actually mean much as the only time you can put your foot down is in the 11pm+ "minicab hours", where 40mph is the defacto speed limit -but it's the thought that counts.

This proposal is clearly pandering to the people who live in the city, at the expense of the commuters from the edges of the town, from North Somerset and South Gloucestershire. Those people, the wealth bringers, need to drive in to the city in their status-vehicles, and now have to face a council even more war-on-motorist than before.

Why do the councillors choose such a short-sighted policy? It's because of the forthcoming mayoral elections. The wealth bringers outside the city don't have any vote in the election, so their needs can be ignored. Such a plan can only bring financial disaster to the region.

One councillor, Peter Abraham, has been bold enough to stand up against this, "it will cause frustration to motorists" he says, before slipping the code-phrase "driving at the right speed for the right conditions". This is the secret handshake of ABD, just as the phrase "indigenous people" is to the BNP.

Sadly for Peter Abrams, the ABD are as completely out of touch with a modern city as the BNP are. Look at our previously documented video of the 20 mph zone of Montpelier:

The frustation that YY03YGM, experiences is not the 20 mph speed limit, which they manage to get past while overtaking the cyclist. No, what is frustrating is

1. The cyclist with the camera doing 18-19 mph in the 20 mph zone.
2. The oncoming bicycle at the junction which forces the car to come to a complete halt.
3. The person walking their dog in the road at 0:56
4. The oncoming bicycle at (1:03)
5. The oncoming bicycle at (1:06)
6. The two children playing in the road on a pogo stick at 1:15
7. The bicycle at 1:25
8. The people walking the road carrying a box at 1:28
9. The car parked in the road with its hazard lights on at 1:30.

These are the problems. Not the speed limit, but the way it encourages people to walk, cycle, -even play in the streets. This is the real problem. It downgrades the residential streets from "rat runs where the right conditions are 30mph even through corners" to "quiet roads where people are walking, cycling and playing there as if it was 1908 and cars hadn't arrived; a country where people driving are viewed as unwelcome invaders instead of an essential part of the life of the city".

This is exactly what threatens us. When the council says "encourage walking and cycling", it means "encourage anti-motorist activities in the city".

As Peter Abraham says, "Are we going to harass the motorists every mile they drive?" 

If you look at Montpelier -that's exactly what they are doing. And it's exactly what the council is planning on rolling out across the entire city.   

Speed signs

Cotham Councillor Neil Harrison has apparently reported that the Cotham-Road speed warning sign was not working. One question: how exactly do you note that it is not working? Very few experiments spring to mind
1. Drive down the road at 35 mph or higher and see if you get told off by the sign
2. Put a speed camera up and see if any vehicles are speeding but while the sign stays unlit.
If the camera actually counted vehicles/day and illuminations/day, then we'd have an interesting data source for traffic volumes and the percentage speeding- and you'd have an easy way to detect failure. But sadly, this is not a feature of these signs, which is a pity. It would then be of datamining value, rather than just decoration.

Now that the sign is apparently fixed, we need a test for that too. Again, the test is simple: drive down the road fast. In a five minute period on Saturday afternoon, 30% of the passing cars appeared to be participating in this test, which shows how much they care about signs working.

Here, for example, is the Audi A055GEY, showing that whatever speed it was doing, it was enough for the light to come on

A lull in traffic provides enough time for some pedestrians to cross. This crossing here is the main crossing point to any schoolkids going to the nursery school on the right-hand-side of the road (mostly from cars temporarily parked in the buses-only parking on the LHS), and for secondary school-age kids going to Cotham Grammar across the road.

With the school rebuilding going on, there is likely to be more pedestrian traffic here. Hopefully the 30 mph sign and a flashing 20mph sign on weekday mornings is enough to ensure safe crossings. That is if the sign works.

Again, a car volunteers to check the sign lights. It's not quite so obvious from the camera angle, but whatever speed it is calibrated too, it has been triggered by a Peugeot.

A period with the sign off would actually be a good basis for a "do these signs actually work" experiment. Turn it off for a month, measure traffic volume and average/peak speeds. Turn it on again, measure the same numbers. See if it has any effect whatsoever.

Correction: The first post called the councillor Neil Hamilton, who was in fact the Conservative-cash-in-an-envelope MP for Harrods; Neil Harrison is the LibDem councillor for Cotham. He says he determined the sign wasnt working it by watching it for 15 minutes as cars went past, and noticing that it never went on. Yes, that would work.

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.

Centre stage at Cabot Circus

Just before Xmas, someone in a Ford Puma coming off the M32 approached Cabot Circus a bit too fast and ended up in House of Fraser, after bouncing off the roof of an Audi waiting at the lights.

The Puma driver ended up in Critical condition at the BRI and went on up to Frenchay for intensive care, the driver of the Audi also ended up at the BRI for chest injuries. The E.P. has some photos. and more text, using the term "accident" as they invariably do, showing a weak understanding of the concept of causality.

This is pretty messy and hopefully all involved will recover; we look forward to the result of the police investigation. What is clear is that the Puma must have been moving fairly fast to travel in the distance and manner that it did. Late at night that whole stretch of dual carriageways between the St James Barton Roundabout, St Pauls Roundabout and templemeads often have cars nipping around very fast on it. The roads are generally structured/styled for fast driving, but it is still an inner city, with junctions, lights and other road users. Which makes for a fairly dangerous combination.

One thing to look at here is whether the new junction changes at the end of Cabot Circus help things or not. It's clear that whoever designed the turn-left feed from Bond Street at the Newfoundland Way junction didn't consider bikes -or other vehicles- running lights, or they wouldn't have given it such atrocious visibility when you look right. When you get a green light, there's no way to see if anything decided to run-the-red without pulling out.

The other thing to consider is how that Dagger-into-the-City, the M32 contributes to excessive speed in the city centre. On a weekday commute the jam begins at eastville, so cars reaching the core have been doing 10mph for 15 minutes. Late at night you can do M4-to-Cabot Circus in 6-8 minutes, at which point your expectations of viable speeds are pretty unrealistic.