Category Archives: Speeding

Some more architectures of control for traffic management

Many of the ‘built environment’ examples discussed here over the last year-and-a-bit have been intended to control (or “manage”) traffic in some way, e.g to slow drivers down, force them to take an alternative route, or force them to stop. I thought it would be worth mentioning a couple of other methods, the rationales behind them, and some of the problems:

Monmouth Thame
Amersham Thaxted
Top row: Monmouth, Monmouthshire and Thame, Oxfordshire; Bottom row: Amersham, Buckinghamshire and Thaxted, Essex. Images from the sites linked.

Historical example: market places

Mediæval market towns commonly had a wide market street, or square, with narrow entrances at the ends, to make it more difficult for animals to escape, and also easier to control when herding them in and out. It may not be immediately obvious from the above photos, but in each of these towns (as with many others where the old layout has been preserved), the market area was, and still is, laid out in this way. It may also have made it more difficult for a thief to escape, since with only a few exit ‘pinch points’, it would make him easier to spot.

This is, of course, almost the opposite rationale to Baron Haussmann’s Paris, with its wide, straight boulevards which prevented effective barricading by revolutionaries and allowed clear lines-of-sight to fire on them.

References: Thaxted at ‘Rural Roads’; History of Thame; Monmouth on Wikipedia.

Pinch point with car overtaking cyclist Pinch point with car overtaking cyclist
Stills from video clips of cars overtaking cyclists at pinch points, from the Cambridge Cycling Campaign website.

Pinch points and other road narrowings

In modern use, pinch points are often installed (along with centre hatching) to force drivers to slow down, usually in built-up areas or at the entrance to them, where there may also be a speed limit change. Sometimes they also force one stream of traffic to stop to allow the other priority, for example when crossing a narrow bridge. Sometimes there are built-out kerbs on both sides of the road; sometimes just a central island; sometimes all three. In general, they prevent drivers overtaking other cars by putting a physical obstruction in the way, even though otherwise it might be legal to overtake. (This is a built environment example of Lessig’s “Code is law” – regardless of what the law might permit or prohibit, it’s the way the system is coded which actually defines what behaviour is possible.)

The problem is that – something which as a driver and a cyclist (and bike designer) I experience a lot – the sudden narrowing of the carriageway causes (forces) drivers to move towards the nearside. And if there’s a cyclist on the nearside, even cycling close to the kerb, he or she will suddenly have a driver passing very close, braking very hard, possibly clipping the bike or actually hitting it. It’s even worse if the kerb is built out as well, since the cyclist has to swerve out into the path of the traffic which may also be swerving in to avoid a central island. In cities such as Cambridge with a lot of cyclists and a lot of traffic, the pinch points are a major problem.

A lot of injuries and deaths have been caused by this ‘safety’ measure. Someone very close to me was knocked off her bike and hurt after swerving onto the kerb to avoid a large truck bearing down on her as the driver tried to fit through a pinch point (similarly to the situation in the photo at the top of Howard Peel’s detailed assessment of pinch points at the Bike Zone). As with so many architectures of control, the designers of these layouts seem to view most users (both drivers and cyclists) as ‘enemies’ who need to be cajoled and coerced into behaving a certain way, without actually looking at what their needs are.

The North Somerset Cycle Campaign’s article on “Good and bad practice” with pinch points shows a far superior layout, for both drives and cyclists (photo reproduced below), from the Netherlands – cycles and cars are kept apart, neither cyclist nor driver is forced to deviate from his/her path, but drivers must give negotiate priority with their oncoming counterparts.

Pinch point in the Netherlands Astonishingly dangerous hatching in Devon
Left: A better pinch point implementation from the Netherlands – image from the North Somerset Cycle Campaign; Right: A very dangerous (and ridiculous) real-world example of hatching-with-obstacles from Devon – image from Richie Graham, discussed in this thread on SABRE

Looking further at centre hatching, this too often causes drivers to pass much too close when overtaking cyclists, since (in the UK), most drivers are reluctant to enter it to overtake even though (with broken lines along the side) they are legally entitled to do so. The reluctance may come from ignorance of the law, but in many cases it is often because there may suddenly be a central concrete island in the middle with no warning. (This is certainly why I’m very careful when using the hatched area to overtake.) Again, this is a de facto imposition of regulation without a legal mechanism enforcing it. As Peter Edwardson puts it:

Two reasons are normally advanced to justify hatched areas, neither of which is entirely convincing. The first is that they separate streams of traffic, but how many head-on collisions occur on single carriageway roads anyway, and surely in the vast majority of cases they involve a driver who has recklessly crossed the white line. The second is that they slow traffic down, which may be true to a limited extent, but again is of no value unless it reduces accidents at the same time…

However, I have recently seen a document from the Highways Agency… that stated clearly that one of the aims of hatched areas was to “deter overtaking”. They daren’t go so far as to actually ban it on straight stretches of road by painting double white lines (although no doubt that will come) but instead they put in confusing paint schemes that have the practical effect of doing just that.

There is of course one entirely sound and legitimate reason for painting hatched areas on the road, to provide a refuge for vehicles turning right, something that in the past has been a major factor in accidents. However such areas should only extend at most for a hundred yards or so on either side of the right turn, and should not be used as an excuse to paint a wide hatched area for a long distance.

In the case of the astonishing (to a UK driver’s eyes) implementation of hatching on the A39 (soon to be A361) Barnstaple southern bypass in Devon – the right-hand photo above – actual bollards have been embedded in the road surface to ‘enforce’ a de facto ‘no overtaking’ intention, though the hatching area actually makes it perfectly legal to overtake. (It makes it worse that the reflectors on the bollards are the wrong colour as well.) Motorcyclists could overtake by weaving between the bollards into the hatched area, but this wouldn’t be especially easy or safe. It would certainly be more dangerous than the alternative situation of wider lanes with no hatching and no bollards. So what’s the point of the scheme?

Shared space at Seven Dials, London Shared space at Seven Dials, London
A Shared Space implementation at Seven Dials in central London, by Hamilton-Baillie Associates

Psychological techniques

We’ve looked before at ‘Shared Space’, ‘naked roads’ and other ‘psychological techniques’ to encourage drivers to be more alert, but Mike Morris sends me a link to this Spiegel story going into more detail and discussing Europe-wide pilot projects:

The utopia has already become a reality in Makkinga, in the Dutch province of Western Frisia. A sign by the entrance to the small town (population 1,000) reads “Verkeersbordvrij” — “free of traffic signs.” Cars bumble unhurriedly over precision-trimmed granite cobblestones. Stop signs and direction signs are nowhere to be seen. There are neither parking meters nor stopping restrictions. There aren’t even any lines painted on the streets.

“The many rules strip us of the most important thing: the ability to be considerate. We’re losing our capacity for socially responsible behavior,” says Dutch traffic guru Hans Monderman, one of the project’s co-founders. “The greater the number of prescriptions, the more people’s sense of personal responsibility dwindles.”

About 70 percent of traffic signs are ignored by drivers. What’s more, the glut of prohibitions is tantamount to treating the driver like a child and it also foments resentment. He may stop in front of the crosswalk, but that only makes him feel justified in preventing pedestrians from crossing the street on every other occasion. Every traffic light baits him with the promise of making it over the crossing while the light is still yellow.

The new traffic model’s advocates believe the only way out of this vicious circle is to give drivers more liberty and encourage them to take responsibility for themselves. They demand streets like those during the Middle Ages, when horse-drawn chariots, handcarts and people scurried about in a completely unregulated fashion.

I think that’s the key to a lot of ‘control-versus-the-user’ debate. Allowing users to take responsibility for their own actions is encouraging them to think. Encouraging people to think is very rarely a bad thing.

One of the simplest consequences of the shared space situations I’ve come across (whether deliberately planned implementations such as at Seven Dials, shown above, or just narrow old streets or village layouts where traffic and pedestrians have always mixed) is that drivers and pedestrians, and drivers and other drivers start to make eye contact with each other to determine who should have priority, or to determine each other’s intentions. Eye contact leads to empathy; empathy leads to respect for other types of road users; respect leads to better understanding of the situation and better handling of similar situations in future. Shared space forces all of us (pedestrians, cyclists and drivers) to try to understand what’s going on from others’ points of view. We learn to grok the situation. And that can’t be bad.

Mike Dickin, the legendary British radio talk-show host who was very sadly killed earlier this week after a heart attack at the wheel, often made the point in his frequent discussions on motoring issues that there should be no need for speed limits in many villages, towns and cities, because in many cases the ‘natural’ limit imposed by pedestrians, other traffic, road layouts and so on, should be enough to slow drivers down to well below the imposed ‘safe’ limits of 20 or 30 mph which lull drivers into a false sense of safety. Of course, he was right, and of course, in most small villages this is still the way things are done, as they were centuries ago, and as Hans Monderman suggests in the above quote.

The age of hyper-regulated behaviour, and treating the user (driver, cyclist, pedestrian) as an idiot incapable of thinking for him or herself, is largely coincident with the age of bureaucratic, centrally planned urban dystopia which sees individuals as components which must all perform identically for the system to operate. I would like to think we can move beyond that view of humanity.

Back to the issue of psychological techniques for traffic management, Jim Lipsey left a comment a couple of months ago mentioning the use of progressively closer painted stripes across the road in Chicago to cause drivers to slow down on a dangerous curve:

In a few weeks, dozens of new pavement stripes will be laid down. At first they’ll be 16-feet apart, but as drivers get closer to the curve, the stripes will only be eight feet apart. “They provide an optical illusion that vehicles are actually speeding up and that causes motorists to slow down, which is of course, the intended effect that we’re trying to have at that location.”

The Chicago example appears to be using only the visual effect to provide the illusion, but a similar technique is often used with raised painted ‘rumble strips’ on the approach to junctions or roundabouts in other countries – e.g. in my (poor) photos below, on the A303 in Somerset, and clearly in this Google Maps image of Ottawa (via this thread).

I remember reading a story once in which someone cycling along an avenue with regularly spaced trees, late one afternoon, had an epileptic fit (I think) as a result of the frequency of the shadow flicker on the road (this is clearly something considered by wind turbine planners [PDF]). Have there been any cases of epilepsy triggered by stripes painted on the road?

Progressively closer rumble strips on the A303 in Somerset Progressively closer rumble strips on the A303 in Somerset
Progressively closer rumble strips on the A303 in Somerset.

Using trees to encourage safer driving

Image from New Urban News, by Eric Dumbaugh
Image from New Urban News, by Eric Dumbaugh

Ryan G Coleman kindly sent me a link to this very interesting New Urban News story, ‘Research: trees make streets safer, not deadlier’. The gist is that roads planted with trees cause drivers to put themselves in state of greater alertness, which makes them generally more cautious about driving and generally slow down:

“Proposals for planting rows of trees along the roads — a traditional technique for shaping pleasing public spaces — are often opposed by transportation engineers, who contend that a wide travel corridor, free of obstacles, is needed to protect the lives of errant motorists…

[However], Eric Dumbaugh, an assistant professor of transportation at Texas A&M… looked at accident records and found that, on the contrary, wide-open corridors encourage motorists to speed, bringing on more crashes. By contrast, tree-lined roadways cause motorists to slow down and drive more carefully, Dumbaugh says.

Dumbaugh examined crash statistics and found that tree-lined streets experience fewer accidents than do “forgiving roadsides” — those that have been kept free of large, inflexible objects. He points to “a growing body of evidence suggesting that the inclusion of trees and other streetscape features in the roadside environment may actually reduce crashes and injuries on urban roadways”…

Dan Burden, senior urban designer for Glatting Jackson and Walkable Communities Inc. in Orlando, notes that there is research showing that “motorists need and benefit from tall vertical roadside features such as trees or buildings in order to properly gauge their speed.”

The article goes on to mention the ‘Shared Space‘ work of Hans Monderman, Ben Hamilton-Baillie and others, which includes removing road markings as part of a wider scheme to change the perceived emphasis of an environment and, again, put drivers into a state of greater awareness. From the BBC article on the ‘naked road’ experiment in Seend, Wiltshire:

“Motoring psychologists and urban planners seem to agree that, overall, “naked roads” appear to have a positive effect on motorists…

“This approach draws on behavioural psychology involving the way drivers respond to their surroundings,” [Ben Hamilton-Baillie] says. “It removes the sense of security provided by barriers – such as kerbs, and traffic lights. Instead of relying on the street system for security, drivers are forced to use their reactions.”

According to Mr Hamilton-Baillie, the removal of a psychological safety net encourages drivers to exercise caution and restraint. He believes that the lack of clear markings encourages drivers to slow down and mingle with pedestrians, forcing them to make eye contact with one another.”

Why are these techniques so much better than this kind of thing?

As so often, I feel it’s better to put users of a system into a state of mind where they are actively, intelligently thinking about what’s going on, and how they can respond to dangers or risks in the environment, than to remove that option for awareness or action planning, and deliberately force them into a state of ignorance of the risks ahead just to compel them to slow down. The driver in the tree-lined or Shared Space road situation can read the road ahead, and adjust his or her behaviour based on the risks that are perceived, whereas just blocking drivers’ vision so they can’t read road hazards ahead and must therefore actually come to a stop, does much less to help safety, and instead merely causes frustration.

Speed control designed to help the user

A keyboard with a customisable extended character pad that I modelled back in 2000 - this was done in an early 1990s UNIX version of AutoCAD, and it shows!

Something with an interesting ‘forcing function’ story has been right in front of me all this time: the QWERTY keyboard, developed by Christopher Sholes and then Remington, with the intention of controlling the user’s behaviour. Until typists became proficient with the QWERTY system, the non-alphabetical layout with deliberate, if arbitrary, separation of common letters allowed the maximum typing speed to be slowed to something approaching writing speed, which reduced the amount of keys sticking and thus benefited both the manufacturer (less product failure, fewer complaints) and the customer (less product failure, less irritation). It also locked users who learned on a Remington QWERTY typewriter into staying with that system (and manufacturer, at least until the patents expired).

Whether or not QWERTY is a real example of market failure (in the sense that it’s an ‘inefficient’ system which nevertheless came to dominate, through self-reinforcing path-dependence, network effects, lock-in, etc), it’s an interesting design example of a commonplace architecture of control where the control function has long become obsolete as the configuration becomes the default way of designing the product.

Would designers today dare to create anything so deliberately idiosyncratic (even if clever) for mass consumption? (Systems that have evolved collaboratively to create complex, powerful results, such as UNIX, probably don’t count here.) The individualistic interfaces of some 1990s modelling software (e.g. Alias StudioTools, Form Z, Lightwave) which required a significant learning investment, were presumably designed with making the user experience easier “once you got used to it” (hence not really architectures of control) but have increasingly fallen by the wayside as the ‘standard’ GUI model has become so commonplace.

Today’s architecture of control is more likely to be something more robust against the user’s adaptation: if for some reason it was desirable to limit the speed at which users typed today, it’s more likely we’d have a keyboard which limited the rate of text input electronically, with a buffer and deliberate delay and no way for the user to learn to get round the system. Indeed, it would probably report the user if he or she tried to do so. Judging by the evidence of the approaches to control through DRM, such a wilfully obstructive design seems more likely.

Returning to the idea of slowing down users for their own benefit, as commenter ‘Apertome’ points out on Squublog:

“One way in which some such designs [i.e. architectures of control] can be GOOD is when mountain biking – a lot of times, they’ll put a tight curve before an obstacle to force you to slow down.”

Note how this is a somewhat different practice to deliberately reducing visibility at junctions: using a bend to slow down a rider before an obstacle does not impede riders who are already travelling at a lower speed, while it makes the higher-speed riders slow down and hence keeps them safe, whereas wilfully removing sightlines at roundabouts would seem in many cases to work to the detriment of drivers who like to assess the road ahead well before the junction, and force all to stop instead.

Deliberately reducing visibility at road junctions

Countess Roundabout, A303, Amesbury, Wiltshire, England (Image from Google Earth)

An increasing trend among road planners in the UK is the use of fencing, hedges or banks deliberately to reduce visibility at certain junctions, especially roundabouts (traffic circles), presumably with the intention of forcing drivers approaching a roundabout to slow almost to a standstill every time, even if the roundabout is empty. This SABRE thread has some interesting examples and discussion of individual cases (including the Countess Roundabout on the A303 – above image from Google Earth*).

I can understand the safety reasoning – and this genuinely is an architecture of control with intended social benefit – but in many places where it’s applied, I believe it to be flawed. One of the main features of roundabouts as originally introduced was that they allowed non-discriminatory free flow to any traffic which was unopposed, i.e. if nothing’s coming from the right (UK) you can proceed without actually having to halt: all roads meeting at a roundabout have to give way to whoever’s already on the roundabout. It’s the ultimate in both deference and empowerment.

By removing drivers’ ability to respond by assessing what’s happening up ahead, you reduce the amount of information available, which apart from sheer frustration, must in many cases have deleterious safety implications.

For example, I drive a low car with a relatively long bonnet. If there’s anything in a lane to my right when waiting at a roundabout, I already either have to wait until that has gone, or nose out gradually, just in order to see what’s coming and whether or not I can proceed. It’s awkward and I don’t like it. Adding high fences to the central reservation forces that situation on every driver.

As ‘PeterA5145′ notes in the SABRE discussion:

“…improving sightlines generally tends to reduce collisions at junctions. You wouldn’t deliberately engineer a road with lots of blind turnings just to make people take more care, would you?

It is nonsense to assert that slower automatically means safer.”

*This image is probably from before the fencing was put up – if anyone has a more recent one showing the fences, please let me know!

‘Carmakers must tell buyers about black boxes’

A traffic jam in south London, 2002

According to Reuters,

“The [US] government will not require recorders in autos but said on Monday that car makers must tell consumers when technology that tracks speed, braking and other measurements is in the new vehicles they buy.
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Dilemma of horns

Night time

I was woken up (along with, I expect, lots of others) at about 5am today by a driver sounding his/her horn in the road outside – an arrogant two-second burst – then another replying (perhaps) with a slightly feeble one-second tone. I don’t know why; there are often a lot of horns during the day as there’s a level crossing which seems to generate a lot of frustration, but there are no trains passing through at 5am. Anyway, I went back to sleep and had various, fitful dreams, but not before thinking that’s where an architecture of control would be useful: a time-related horn interlock function, only allowing use of the horn during hours when it is legal. In the UK, that would be from 7am – 11.30 pm.
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