Do we need so many traffic lights?

Posted on April 21st, 2009 in Driving Emotion,Opinion by Julian Edgar

Back when I was a kid, growing up in the northern suburbs of Adelaide, every six months or so there’d be some local excitement.

Normally it was presaged by a squealing of tyres, followed by a loud bang. On one occasion I can remember that after the bang there was the sound of an engine revving hard.

What had happened was a car crash at one of the local road intersections.

All the roads were grid-like; all used the ‘give way to the right’ rule – I don’t remember any ‘stop’ or ‘give way’ signs at those junctions. 

The frequency of crashes was so high that when the right noises occurred in sequence, no-one stood around wondering what was going on: instead, everyone started running towards the scene.

Then, when I was about 13 or 14, the crashes suddenly stopped. What had happened was that small roundabouts had been placed in the intersections where crashes had most frequently occurred.

I don’t remember hearing a single crash from that point onwards. There might have been some minor bingles, but as the intersections had become quite tight, they would have been only at low speeds.

At the roundabouts drivers were travelling less quickly and were also required to be observant and participatory. Well, certainly less quickly, and more observant and participatory, than they had been when barrelling through a junction with just a cursory glance to the right.

I was reminded of my childhood because I have been increasingly hearing the idea that many traffic lights should be removed. That’s especially the case on secondary and tertiary (feeder) roads.

The arguments go like this:

• When traffic lights are green, people assume an absolute right of way. They don’t check for other cars and in fact, pay little attention to anything other than the colour of the light. So when crashes occur at traffic light controlled intersections, the impact speeds are high and so the crashes are likely to cause death or major injury.

• Even traffic lights controlled by smart systems (variable length time periods, sequencing of green lights on successive intersections) can, through prolonged idling times, cause increases in fuel consumption and emissions.

• The cost (both in installation and in running) of traffic lights is much higher than many other traffic control approaches.

It is being said by some that rather than giving driver apparent certainty, it is better in many situations to create uncertainty – to make the driver unsure of their surroundings. Perhaps the best example of that are those (rare in Australia) precincts that mix both pedestrian and vehicular traffic – cars just creep along at a walking pace.

Of course, in many applications traffic lights are just fine.

But the next time you’re out on the road in city conditions, note the dozens – perhaps hundreds – of traffic lights you pass, and start to consider: are these really necessary… or could this intersection have been handled in a different, simpler, cheaper and more effective way?

I’m no natural designer…

Posted on April 16th, 2009 in Opinion by Julian Edgar

I am not a natural designer; never have been and never will be.

The designs I produce are therefore the work of many hours of tortuous thought: of sketching and thinking; of looking up reference books and thinking some more.

Even a simple bracket can take me a long time; a more complex system can take me so many hours that, to be honest, you’d be frankly disbelieving if I told you the total.

How I envy those who combine natural artistry with engineering skills; those who have the ability to create beautifully elegant structures and shapes that also perform with engineering integrity. I think of those attributes – and the people who spring to mind are designers of bridges, of buildings and of dams: civil engineers and architects, rather than mechanical engineers.

Isambard Brunel and Thomas Bouch, certainly.

In the automotive field, it is hard to think off-hand of revered designers who could combine artistry with engineering elegance.

Colin Chapman?


Ferdinand Porsche?

More so, I think – but ‘Porsche’ normally also includes son Ferry… so perhaps you’re getting two for the price of one.

Gordon Murray?

Yes, probably so.

Alex Issigonis?

Engineering? Without a doubt! Aesthetics? He had no bloody idea.

Anyway, as I was saying, automotive designers tend not to be able to combine innovative ideas with artistry.

Me? I can’t do innovation or aesthetics!

But I can try.

One of the outlets for my attempts has become, over the last few years, human-powered vehicles. Pedal bikes and trikes, if you like.

(A few years ago I had steel coil springs custom-wound for the suspension of a recumbent pedal trike I’d designed.

When I contacted the spring company – and in following discussion – I called the vehicle a ‘human-powered vehicle’.

When I picked up the springs, the salesman loudly proclaimed: “So these are for the bike, are they?”, by emphasis and with a touch of derision, clearly making his thoughts felt.

I replied: “Well, it’s got three wheels, so that makes it a trike doesn’t it?”

With visions of a child’s tricycle filling his mind, he was speechless.)

One of the beauties of building an HPV is that you can try pretty well anything you want – both legally and physically.

In my first really successful HPV, I used a front suspension design comprising semi-leading arms, with an anti-roll bar and a high geometric roll centre. Damping was by track change and Firestone rolling lip airbag springs were the springing medium.

(And if you think: “Yeah, whatever – WTF… that’s how I was too a few years ago. Boy, does building our own vehicle make you think hard about fundamental concepts of vehicular design!)

With its massively high roll centre and changing track, varying castor and camber, this suspension design went against almost everything I have ever read about suspension (for any vehicles!) – but on-road, it proved to be very good indeed.

And to be quite honest, that makes me feel warm inside: I did something that, AFAIK, no-one else has done on a vehicle – and it worked!

(Of course, someone, somewhere must have done it – but it’s certainly not a recognised front suspension design.)

Today, I got to the stage in my latest HPV build that I could statically assess the new front suspension – in terms of travel and roll stiffness, at least. (As I write this, the machine is at least another week away from road testing.)

And, at this early point in the design, it looks really good.

How so?

Well, it resists dive more than a single wheel bump. In fact, it has a much lower spring rate for a single wheel bump than a two-wheel bump. And, since most bumps are one-wheel, that’s good.

It incorporates the function of anti-roll bar into a suspension member. That saves potentially a lot of weight – not just for the anti-roll bar, but also for the links and rod-ends and anti-roll bar bearings.

And the suspension design has only four ball bearings (at a total of two pivot points).

…and it weighs – including suspension arms, pivot point bearings and two springs – just 1.4kg.

To carry a max dynamic load of about 150kg.

Its design? It’s a leading arm, torsion tube, dead axle, with a Watts link.

Weird? Very!

Unheard of? Again, I am not aware of any vehicle of any description using this approach on the front, steering, suspension.

Effective? I’ll find out when plunging down my local 20 per cent grades at 60 or 70 or 80 km/h, clad only in shorts, shoes, a t-shirt and bike helmet…

Beware the expert…

Posted on April 14th, 2009 in Driving Emotion,Opinion by Julian Edgar

Experts? I wonder…

A long time ago I came up with an electronic way of overcoming a boost cut on a turbo car. For less than a dollar, you could prevent a MAP sensor output from rising above a certain voltage. And for that single dollar, the voltage level was also adjustable.

At that time (and remember, it’s long ago – when I was certainly a lot more innocent), I told a turbo workshop proprietor about the technique, and how I was writing a story on it for a national magazine.

As this guy sold commercially produced boost cut units for lots of money, I thought he’d be fascinated by the approach.

But no, not a bit of it.

“You shouldn’t put that sort of technology into the hands of people who don’t know what they’re doing,” he said.

“Today’s cars are complex and people will blow up engines.”

When I pointed out that  someone could blow-up their engine if you gave them even a screwdriver, he was taken aback.

Of course, the reason he didn’t like the idea of a DIY $1 boost cut unit was that his market for $200 ones was likely to evaporate.

So one reason that experts hate amateurs working in their patch is that often it costs them money.

Another reason is more subtle: it implicitly belittles their expertise and training.

I remember once when I was getting a lot of arc welding done. I was building a supercharger bracket and the 10mm steel plate was being welded by a local welding specialist. He was doing a very good job, too – and at a high cost.

Watching him in action, I thought I should invest in an arc welder – and the next week I bought a cheap secondhand welder. When he was doing my next lot of welding I told him of my purchase, expecting that he would be enthusiastic.

But as with the boost cut man, again not a bit of it.

“It takes years of experience,” he said. “You can’t pick up the skill of welding just by buying one.”

I hadn’t even implied that I could, but again his negative vehemence was off-putting and surprising.

Given that I’d been pouring money into his pocket, I thought he might have said: “Great! If you need any tips or get stuck, just ask.”

But no, I’d hurt his pride by apparently suggesting than anyone could buy a welder and so be an expert.

The third category of expert to be wary of is the person who ridicules any simpler approach to solving problems at which they’re specialists.

I’ve seen this in action most recently, with my copper wire modelling approach to designing space-frame structures. The experts look at the approach and nearly choke on their cornflakes.

“You can’t work out any stress levels,” they say. “You cannot accurately model anything by that approach.”

Of course, when asked how else to design space-frames (without using engineering mathematics or complex and hard to access software), there are no answers. Apparently, it is better to simply not attempt to design and build a space-frame, rather than to do so with an approach that has huge benefits over using no aids at all.

The corollary of all of this is that experts believe you should work only in your professional field of expertise, that – in other words – no hobbies should be embraced, no amateur past-times partaken in.

When it’s put like this, you can see the mixture of vested interests, pride, and the inability to understand that expertise can be reducible, invariably results in expert denigration of non-experts attempting anything.

I’ve seen it so often over the years: not only the aforementioned boost cut over-ride, welding equipment and space-frame modelling; but also aerodynamic testing by wool-tufts and pressure measurement, intake flow testing by pressure measurement, turbo boost control using injector duty cycle as the sole input, turbo boost control using a pressure regulator, single dimensional voltage interceptors working on the airflow meter signal, making trial aero undertrays out of cheap plastic sheet or cardboard, making plastic intake ducts from stormwater pipe and fittings, forming door pods for speakers using expanded polystyrene, swapping-in springs from other cars, DIY detonation detection systems, fitting a rear anti-roll bar, using suspension on human-powered vehicles, fitting your own subwoofer, using a pot to shift a voltage signal, altering regen braking on a hybrid car – the list goes on and on.

In fact, I can state that for every innovative, DIY technique we have ever covered in AutoSpeed, at least some experts have suggested the approach would not work. But in every case the techniques have worked extremely well!

I reckon that often you can get further ahead by actively ignoring experts. That’s especially the case if the technique is one that you have devised yourself and have found to be effective…

Building (another) failure

Posted on April 9th, 2009 in Opinion,pedal power by Julian Edgar

I think it was after I crashed for the third time that I started losing confidence in my new machine.

All were low-speed crashes, but still, they were hitting-the-ground crashes. Just as well they were from a pedal bike.

After the saga of the pictured first Chalky (front-wheel drive, delta, leaning, recumbent, suspension design) that reached the stage of being about two-thirds finished before I decided that the build was not going the in the direction I had hoped, I was very excited about the second Chalky.

This one was much more conventional – in terms of weird human-powered machines, anyway.

A long-wheel base, recumbent, rear-wheel drive, suspension bike. I had plans for rider-operated ‘trainer wheels’ to provide low speed stability, but I secretly hope that it would be stable enough to be easily ridden without them.

I used the same static front end geometry as the Greenspeed Anura and ran 130mm of suspension travel front and rear, using my favourite Firestone airbags. The rear had a chain path positioned for anti-squat suspension behaviour, and I investigated very thoroughly different types of anti-dive front suspension designs.

And, after many hours of work brazing the (very expensive) chrome moly tubing, I had a machine I could ride.

Ride – and fall off.

I don’t want to over-emphasise the falling off bit, but still, it wasn’t good.

Because a recumbent like this has more weight on the back than the front, and because it is steering of the front wheel that provides the balance (ie puts the centre of gravity over the line joining the front and rear tyre contact patches), on this sort of bike a fair bit of steering is needed to stay upright. I experimented with different steering ratios until I had quick – but not nervous – steering. I also dialed-out all bump-steer.

I experimented with different positions of the front suspension’s upper leading link, and while I could reduce brake dive, it also increased (to an unacceptable level) suspension harshness. 

Talking about the suspension, I also think the spring motion ratios were not right: the machine bottomed-out excessively. To prevent simultaneous nose-dive and bumps bottoming the front end, I added a long bump rubber – but the main spring rate was clearly still too low.

The high centre of gravity and soft front spring rate meant that, with vigorous pedalling, full front extension occurred – the rear anti-squat worked fine but the front suspension extended each time.

In short, it was simply nowhere near as good as my existing recumbent trike – nowhere near as good.

Yes, the design of Chalky #2 potentially allows for folding into a small package, but if the stability, ride, and pedalling suspension behaviour are way inferior, it’s hard to justify this approach as the way to go….

In short, I think it’s another failure.

So I’ve started designing Chalky #3…

My driving life is now changed forever…

Posted on April 3rd, 2009 in AutoSpeed,Driving Emotion,Economy,electric,Electric vehicles,Global Warming,Opinion by Julian Edgar

I feel like one of the first pilots of jet-powered aircraft. They immediately knew that they were flying the future: there could be no going back to pistons and propellers.

Today I drove the car that, for me, spells the end of the piston engine for performance cars.

The car was the all-electric Tesla, and its performance – and the way it achieved that performance – was just so extraordinary that I am almost lost for words. That a start-up car company has created such a vehicle is simply unprecedented in the last century of automotive development.

For the Tesla is not just a sports car with incredible performance (0-100 km/h in the fours) but also a car that redefines driveability. Simply, it has the best throttle control of any car I have ever driven.

Trickle around a carpark at 1000 (electric) revs and the car drives like it has a maximum of just a few kilowatts available. It’s the pussy cat to end all pussy cats: Grandma could drive it with nary a concern in the world. Put your foot down a little and the car seamlessly accelerates: heavy urban traffic, just perfect.

But select an empty stretch of bitumen and mash your foot to the floor and expletives just stream from your mouth as the car launches forward with an unbelievable, seamless and simply immensely strong thrust.

There are no slipping clutches, no flaring torque converters, no revving engines, no gear-changes – just a swishing vacuum-cleaner-on-steroids noise that sweeps you towards the horizon. The acceleration off the line and up to 100 km/h or so is just mind-boggling – especially as it’s accompanied by such undemonstrative effort. The car will do it again and again and again, all with the same phenomenal ease that makes this the winner of any traffic lights grand prix you’re ever likely to meet.

And it’s not just off the line. Want to quickly swap lanes? Just think about it and it’s accomplished. 

In fact drive the car hard and you start assuming that this is the only mode – outright performance. But then enter that carpark, or keep station with other traffic, and you’re back to driving an utterly tractable car – in fact, one for whom the word ‘tractable’ is irrelevant. Combustion engines are tractable or intractable; this car’s electric motor controller just apportions its electron flow as required, in an endlessly seamless and subtle variation from zero to full power.

It’s not just the acceleration that is revolutionary. The braking – achieved primarily through regen – has the same brilliant throttle mapping, an approach that immediately allows even a newcomer to progressively brake to a near-standstill at exactly the chosen point.

A seamless, elastic and fluid power delivery that no conventional car can come remotely close to matching; a symphony on wheels to be played solely with the right foot; an utterly smooth and progressive performance than can be explosive or docile, urgent or somnambulant – literally, a driveline that completely redefines sports cars.

There’s no going back – my driving life is now changed forever.

Footnote: the Tesla drive was courtesy of Simon Hackett of the ISP, Internode.

When wheels steer themselves

Posted on April 2nd, 2009 in Driving Emotion,Handling,Suspension,testing by Julian Edgar

I thought that the idea that car wheels just went up and down over bumps, and were steered only when the driver turned the steering wheel, was pretty passé.

Passive ‘steer’ systems have been in production cars for many years, normally of the rear end.

In broad brush strokes, the systems work like this: The rear bushes are set with differing stiffnesses in different planes, such that when the wheel is subjected to a lateral force (as it is in cornering), it no longer remains parallel with the car’s long axis – that is, it steers.

For example, rear wheel compliance steer is often set to give toe-in, thus settling the cornering car.

The original Mazda MX5 / Miata had such a system. (It’s worth pointing out that the MX5 is generally regarded as one of the best handling, relatively cheap, cars ever released.) In their 1989 book MX-5 – the rebirth of the sports car in the new Mazda MX5, Jack Yamaguchi and Jonathon Thompson write:

No Mazda rear suspension is complete without some form of self-correcting geometry, as have been seen in the fwd 323 and 626’s TTL (Twin Trapezoidal Links), the 929’s E-links and the RX-7’s complex DTSS. The MX-5 double wishbones are no exception, though to a lesser degree. The designers need not worry about camber changes; a recognized virtue of the unequal length A-arm suspension is the admirable ability to maintain the tires’ contact area true to the road surface, attaining a near-zero camber change.

So the chassis designers’ efforts were directed at obtaining a desired amount of toe-in attitude that improves vehicle stability in such maneuvers as spirited cornering and rapid lane changes. Toe-in was to be introduced when the suspension is subjected to lateral force, not to accelerative or braking force. They considered that the MX-5 with its configuration, weight and suspension, would have sound basic handling characteristics, and the lateral reaction would be all it would require to further enhance its vehicle dynamics.

The lower H arm’s wheel-side pivots, which carry the suspension upright, have rubber bushings of different elasticity rates. The rear pivot is on a firmer rubber bushing than the front. The front rubber bushing deforms more under load induced by lateral force, and introduces an appropriate amount of wheel toe-in, which is in the final production tune a fraction of a degree.

Pretty well all current front-wheel drive cars have some form of passive rear wheel steering. The Honda Jazz uses a tricky torsion beam rear axle in which, according to Honda, “the amount of roll steer and roll camber has been optimised to deliver steady handling”.

But even better, the company has released graphs showing the toe variation over suspension travel (note: travel, rather than lateral force), with the current model compared with the previous design. As can be clearly seen, in bump (as would occur to the outer wheel when cornering) the Jazz (especially the new model) has an increasing amount of toe-in. Also note the differing shape of the curves in rebound (droop).

And it’s not just the ostensibly non-steered end that uses toe variations built into the suspension design.

Several suspension textbooks that I have suggest that setting up the front, steering wheels for non-zero bump steer can be advantageous. Chassis Engineering by Herb Adams (incidentally, a very simple book much under-rated) states:

Exactly how much bump steer you need on your car is like most suspension settings—a compromise. It is common to set the bump steer so that the front wheels toe-out on a bump. This will make the car feel more stable, because the car will not turn any more than the driver asks.

To understand this effect, picture what would happen if your car had toe-in on bump. As the driver would start a turn, he would feed in a certain amount of steering angle. As the car built up g-forces, the chassis would roll and the outside suspension would compress in the bump direction. If the car had toe-in on bump, the front wheels would start to turn more than the driver asked and his turn radius would get tighter. This would require the driver to make a correction and upset the car’s smooth approach into the turn. The outside tire is considered in this analysis because it carries most of the weight in a turn.

Assuming that your car has the bump steer set so that there is toe-out in the bump direction, the next consideration is how much toe-out. If the car has too much toe-out in bump, the steering can become imprecise, because the suspension will tend to negate what the driver is doing with the steering wheel. Also, if there is too much bump steer, the car will dart around going down the straightaway. A reasonable amount of bump steer would be in the range of .010 to .020 per inch of suspension travel.

Fundamentals of Vehicle Dynamics by Thomas D Gillespie positively describes using roll steer, where the toe variation of the left-hand and right-hand wheel is in the same direction, to alter understeer and oversteer effects.

Even that most exotic of road cars, the McLaren F1, had designed-in passive steer.

Writing in an engineering paper released in 1993, SJ Randle wrote of the front suspension: “Lateral force steer…. was 0.15 degrees/g toe out under a load pushing the contact patch in towards the vehicle centreline. This is a mild understeer characteristic – precisely what we wanted.”

In the case of the rear suspension, “the net result being a mild oversteer characteristic (ie toe out under a force towards the car’s centreline) or around 0.2 degrees/g. We had hoped for an understeer of 0.1 degrees/g.”

Such passive steer suspension behaviour would become especially important in vehicles that, in order to achieve other design aims, have dynamic deficiencies. So for example, a very light car that is aerodynamically neutral in lift, and has a low aero drag, is likely to be susceptible to cross-winds. On bump the passive toe-in of the rear wheels, and toe-out of the front wheels, would help correct this yaw.

Note that adopting these techniques doesn’t require the actual mechanical complexity – or weight – of the suspension systems to change.

But of course it’s quite possible to over-do these effects. As indicated in the quotes above, we’re talking very small steer angle changes. You can’t even transfer the ideas from car to car: the current Honda Jazz steers fine; the Honda City (that apparently uses the Jazz rear suspension) has an unmistakeable, unhappy, ‘rear steer’ feel that is disconcerting on quick lane changes. 

But it seems to me that if you are building any bespoke vehicle and simply state point-blank that there should be no bump steer at the front, and no lateral compliance leading to toe changes at the back, you’re taking away a pretty important string from your bow.

The Best DIY Tools and Techniques

Posted on March 31st, 2009 in diesel,Driving Emotion,Economy,Mufflers,Opinion,pedal power,testing by Julian Edgar

This week in AutoSpeed we start a new series that I’ve immodestly called the ‘Ultimate DIY Automotive Modification Kit’.

It’s not the sort of material that you’d find anywhere else but at AutoSpeed – and, perhaps for that reason, longstanding readers will have seen much of the content before.

What the series does is integrate the testing and modification techniques that over the years I’ve discovered  to work for all cars.

Yes, all cars.

The Hidden Story of Reader Ratings

Posted on March 26th, 2009 in AutoSpeed,Driving Emotion,Opinion by Julian Edgar

At the end of all AutoSpeed articles is a reader rating system – you can give any article a score from 1 (bad) to 5 (excellent). As you’d expect, AutoSpeed publisher Web Publications has internal data analysis and display of these reader ratings – now totalling literally hundreds of thousands of scores.

By importing the data into a spreadsheet, I can rank all our articles in terms of numbers of ratings, averaged ratings for individual articles, and so on. I can also see changes over time in the average reader ratings for specific articles.

The other day a reader proposed that, if an article suggests to people ideas they don’t want to hear, they are more likely to give it a low score. So in other words, instead of rating articles on the basis of the quality of journalism, expression, innovative ideas (etc) that are presented, they just rate it on the basis of whether or not they agree with it.

350kW and 0-100 km/h in 4.6 seconds

Posted on March 24th, 2009 in AutoSpeed,Driving Emotion,Intercooling,Power by Julian Edgar

Today I was lucky enough to drive an interesting car.

A 2003 model AMG Mercedes Benz E55, it comes standard with a supercharged 5.4 litre, 3-valves-per-cylinder V8 boosted by a Lysholm compressor spinning at up to 23,000 rpm and pushing air through a water/air intercooler.

Lies, damned lies and statistics!

Posted on March 19th, 2009 in AutoSpeed,Driving Emotion,Opinion by Julian Edgar

From here:

Although sometimes attributed to Mark Twain – because it appears in his posthumously-published Autobiography (1924) – this should more properly be ascribed to Disraeli, as indeed Twain took trouble to do: his exact words being, ‘The remark attributed to Disraeli would often apply with justice and force: “There are three kinds of lies: lies, damned lies, and statistics”.’

And there are no greater ‘damned lies’ than readership or circulation figures for magazines and other publications. To give you an idea, often when a print magazine quotes ‘readership’, they triple or even quadruple their actual sales figures. Why? Because they assume each copy is read by three or four people!

In the same way – or even, come to think of, much worse ways – web sites quote all sorts of figures for their readership.

AutoSpeed’s figures are logged by Google. I can look at our daily figures, weekly figures, annual figures – or even figures for the content, section by section. Further, through internal Web Publications data, I can view readership numbers, article by article. Finally, I can also see the number of reader ratings for each article, and what those ratings are.