Google's robot cars and what it may mean for classic cars

So, apparently Google has cars driving around guided purely by computers. Robot Cars. The idea has been around since the 60ies, but few years ago the electronics/hardware still took most of the passenger and boot space. This is getting better by the day. Google's cars are Toyota Prius and obviously there's still at least enough space to seat a control person and a passenger, maybe more. Now people say that this may open a new development similar to the impact of the internet. With robot driven cars you can reduce accidents, put more cars on the road on less space and make cars lighter and more economical as they will prevent accidents rather to have a lot of passive safety built inside. That would be good news as such. But obviously this only makes sense if all the cars follow the same logic and if we have less software errors built into these cars than into the odd MS Excel or Word. And I am a bit afraid, this is not good news of us who keep classic cars on the road and try to mesh into daily traffic. These robot cars will not know that a vintage automobile may easily take 100 meters to brake from 100 km/h to 0, or more.
But anyway, until we have these robot cars on public roads, a lot of legal and technical hurdles need to be removed, so let's get excited when it's here ...

Radar speed control detection in 1961

A long time ago, in 1961, the company Hamos (New York) introduced a radar (speed control) detection unit to be installed in cars. Given that cars barely were able to go beyond 100 km/h and the low probability of a speed control exercise the purchase of such a (expensive) unit may sound a bit "beyond" today. But it's interesting to know that the "problem" was acknowledge already 50 years ago, isn't it?
And it's also funny to see that the company already in 1961 claimed to increase road safety with this device.

Parking with classic cars is really much easier!

It's now official! Auto Motor and Sport compared a range of cars including the Volkswagen Touran, Mercedes E-Series Convertible, Toyota Prius, BMW 5-Series Station Wagon and a number of others in how easy it is to park them. They measured how much you can see from the driver position, how big the car is, how easy it gets into a 5.5 m parking spot and a number of other criterias and they also looked at the electronic gizmo to help with parking. Well, the winner is, the BMW 3-series E30 limousine from the 80ies. It actually has beaten the modern cars by a factor, thanks to the smaller body, the great 360 degree view and the fact that you can actually see the end of the car when you sit in it. Despite the fact that none of the modern accessories was on board, i.e. park distance control, parking assistance, cameras, etc., the people at AMS found it much easier to park this car compared to the modern rivals. I am really happy that they brought in this 80ies benchmark when comparing the modern cars, as this now so transparently shows how cars got worse along these criteria over time. Of course there are reasons, why modern cars are as they are, one being safety. But even with today's standards cars could have larger windows and better visibility today, if the designers didn't think differently.

Will the latest "super radar" make driving and traffic more safe?

There's a lot of discussion these days around the latest radar traffic supervision technology coming from Multinova in Switzerland. The new technology is able to track multiple cars (i.e. 18 or more) concurrently and to find out whether one of them is too fast, neglecting a traffic light or a stop sign and probably other mistakes as well. In general these things get cheaper and better in parallel with other technology developments and Moore's law. Soon, you will be able to basically detect any mistake people can make on the road. Nice vision for the future, isn't it. But does it make traffic more safe? Partially it probably does, as speeding can be dangerous, not keeping enough distance to other cars can create accidents as well, neglecting stop signs and traffic lights of course is not good as well. But sometimes it can be more safe to be a bit faster than what is on the signs, for example when you overtake. Sometimes it would be better people would look ahead and observe the traffic than looking for radar cameras. Sometimes speed limits just don't make sense at all. Before we leverage all available technology to observe car drivers, maybe we should think about tolerances and exceptions as well?

Classic sportscars safety isn't as bad as you thought ....

... if you watch the crash test TopGear showed in its last episode. The setup was taking a truck, driving a traditional hatchback or a sportscar against it and see the difference.
And if you take a really flat car and tweek the height of the truck a bit you can proof anything of course.
But, of course, this is not to be taken seriously. Safety of classic cars is primarily dependent on the driver, as the car will not offer a lot of passive and active safety features. If you are aware of this, then all is fine. So drive carefully, look ahead and plan for safety tolerances.

How many active and passive safety features do you need? Salmson GP Car

I just came across this Salmson GP car, it's named "Salmson San Sebastian GP" and stems from 1927. It's offered by VDV Grant. I love these pre war racing cars. They are so nimble. I could even imagine buying a car like this, but there's no price indicated and probably demands significant funds given history and condition. However what caught my eyes was the following sentence in the online ad: The Salmson "Grand Prix" is very easy to drive; docile at lower r.p.m, easy to start and copes well with today's traffic." Wow! Think about taking one of today's grand prix cars for a drive to your favorite downtown restaurants. Not only you need a truck with computers and a team of 10 or more people to start the car, it probably wouldn't survive many traffic lights before it either overheats or the clutch dies.
But driving a car like the Salmson in today's traffic also puts another question into the center: How many active and passive safety features do you need? To be clear, the Salmson basically has none of them. But since the 1920ies a lot has been invented to make driving more safe! Passive safety features like the collapsible steering column, crash cells, safety belts, anti lock brakes or the airbag are just examples. Modern cars can actually detect a crash before it happens, can influence brakes, steering or throttle and even the angle of the rear wheels if it's needed to prevent an accident. So, clearly, driving has become much more safe. You may mention that also the driver has an influence on whether an accident happens and he can compensate for the lack of ABS (anti lock brakes) or ESP/ETC and the likes by driving more carefully or being more skillful. That's probably true, however sometimes it's just not in the driver's hands really. And then you prefer having 3 airbags opening just in time to prevent injuries. So, what is the right classic car then do both enjoy and use in modern traffic? There's not single answer to that, but clearly, during the late 70ies and the 80ies a lot of safety has been added to the cars produced then and you certainly are better off with safety belts than without!

Adaptive Cruise Control - is this the start of the auto pilot for cars?

What we know as "Cruise Control" (other terms are Tempomat, Tempostat, etc.) has been introduced by Chrysler in 1958. Mercedes-Benz was the first European manufacturer adding cruise control to a car in 1962. For years the cruise control mechanism mainly controlled the throttle. With the enhancement of modern electronics mechanical approaches to do this were replaced by sensors, electronic steering signals and computer control. And after controlling the throttle car manufacturers added the controlling of the brakes. Which makes a lot of sense, as when you go downwards it would nice to still keep the speed. In 1998 Mercedes-Benz added radar to the equation and started to measure the distance to the cars in front of the controlled car to adapt the speed based on traffic flow. These systems are called Adaptive Cruise Control (ACC). The version of Volkswagen is displayed in the picture. So, it took 30-40 years to get from throttle control to brake and throttle control and another 10 years to add traffic flow and advanced computer control. But what's next? And what is the disadvantage of ACC systems?
First, let's start with the disadvantages: ACC doesn't increase the capacity of highways and streets it actually rather decreases it. ACC tries to always keep the preset distance to the car in front of you. This leads to a lot of breaking and acceleration, which is bad for street capacity usage, but also for fuel consumption. In certain situations the systems even interpret the traffic context wrongly.
There are of course advantages too. For the driver it can be relaxing to not having to think about speed, throttle and breaking. And ACC systems can prevent accidents, as the can brake down a car completely if the driver doesn't react quickly enough himself.
But what would be the perfect solution? Imagine a traffic lane with all ACC controlled cars and computers actually talking to each other so that the car behind knows already that the car in front of him will brake before actually "seeing" it. With this you could decrease the distance between the cars and increase the capacity of the lane. For the car drivers it would almost be like riding on a train. The cars could even take over the steering, the technology is already out there.
Of course this would mean that non ACC cars could not play the same game and of course driving a car would be a lot more boring than today. Which is why I wouldn't be a fan of such a system. I actually do not really like the ACC. But cruise control clearly is a necessity today, as it's the only way to make sure you do not speed in cities and on heavily monitored highways (speed cameras).

Mercedes 500 SL (R129) - innovative and a great tourer

The Mercedes-Benz 500 SL (R129) was a very modern car in the 90ies and showcased innovative engineering. It was one of the first convertibles with a fully automatic roof mechanism. And it had the latest and best safety technology such as an automatically rising rollover bar on board. The design by Bruno Sacco was seen as state of the art and very attractive in 1989 when the car was launched. The fact that they were able to build (and sell) 204'940 cars in 13 years is proof that it was a success. Mine was a blue 1993 model with the fabulous 5 liter V8 engine and it was both comfortable and relaxing to drive. Mounting the hardtop though was a pane and I don't understand why the first owner had a stationary heater unit installed. Actually the car had almost any accessory that was on the pricing list. I liked the shape and the design, but looking back or seeing them on the road today I must admit the design didn't age well depending on the perspective you look at the car. But it was a good car to use with our then small family for holiday and weekend excursion purposes. And it was a good business vehicle as well.

Air Conditioning in cars - a long journey since the 60ies

In 1939 Packard equipped the first car with Air Conditioning. The system apparently used the whole trunk space. Since then we came a long way. Not only the systems got smaller and lighter, they also became more efficient and effective. In 1969 already more than half of all domestic cars were sold with an air conditioner. Not so in Europe, where it took quite a bit longer to achieve this level of adoption. This had also to do with pricing. In 1980 for example the air conditioning option for a BMW or Mercedes was priced at about DM 3'000 to 4'000, about half the price of a decent compact car, or 5-15% of a family sedan! And some of these systems were pretty crude, i.e. you could turn them on or off and maybe influence the "cooling down" factor and the wind speed of the vent. At least that's what the system in my Berlinetta Boxer was all about. Many of these systems actually were not able to really cool down a car on a hot day. Today this is quite different, as a lot of engineering has gone into this (mostly standard) option. Not only they need much less energy, they are also fairly small and quite unexpensive. Forgotten the days when you had to turn the aircon off if you wanted to overtake. Air conditioning makes driving cars safer not only because the driver's reactions are better in a cooler environment, but also because the systems take humidity out of the air and improve overall visibility. So, all in all, here's some good engineering applied to everyday's problems.

Starting the new year with old impressions - Semperit advertisement from 1964

A new year, a new decade! Wet and cold weather conditions. So that's a good moment to clean up the house and the things collected over the last decade. That's when you come across such things as the advertisement pictured here. It's for Semperit, a tyre manufacturer. A happy couple driving in a "virtual" car. In 1964 (or before). With a white plastic steering wheel. Wonderful! And it talks about handling, comfort and safety. You don't see ads like this anymore.

How virtual is driving a real car today?

Some of us have been playing with a Playstation or Xbox and trying to drive fast around the Nurburgring. It's clearly quite different to the real thing. There's a lot missing despite the always improving graphics and more and more computing power. Not even a 720 degree turning steering wheel makes the sensation really real. But is "real" driving really real? More and more of what we do in a car isn't directly influencing mechanical elements but rather sensors and digital processors. When you step on the throttle today a computer decides how much of your command is really good for the engine and the driving condition. And when you turn into a corner your wheels in the back may also turn to make the driving safer. Engineers work hard to still give us "feedback" and make the driving less artificial, but in reality not even the sound of the engine may be real, as modern cars like the new Lexus LF show. So more and more real driving becomes virtual and at the same time virtual driving becomes more real. Brave new world!

How much better is a 2010 Volkswagen Polo compared to its grandfathers?

I have been criticizing the lack of progress in car engineering again and again. But now it's time to also look at it from the other side for once. Having just read a couple of old car magazines - something that I enjoy a lot - and compared it with what is published as test reports today, some interesting facts come together.
If you take a modern car like the VW Polo (1.2) and let it compete with a VW Golf (1.3) built thirty years ago you can just see how much progress has been made. Despite the fact that the Polo is almost 300 kg heavier at about the same size, performance in comparison is staggering. The Polo accelerates better, is much faster, much more quiet (by a lot) and much more economical. Actually the current Polo is as quick as the top end model VW Golf GTI from 1979/1980. The Polo even beats a proper midrange car like the Audi 80 GLE (this one would be called Audi A4 today). It's faster, offers more space (look at the seat pitch for the people in the back of the car!) and again is much more quiet and thirsty. In addition to all of this the new car is of course much more safe (with 4+ airbags, crash protection, ESP, etc.) and much much cleaner. You actually wonder why anybody would need a bigger car, given that the Audi 80 was already luxury in the late 70ies. So, one must say, that the engineers did a lot of homework and progress is really well visible. So it's down to the consumer to make the right choice and take profit from the progress.
Two things to also mention: The Audi 80 GLE was DM 17'671, the Volkswagen Polo is priced at Euro 17'250. So, for the today's price of the Polo you would have received roughly 2 Audis, if the value of money hadn't decreased. But, as another measure, you could also have bought a Porsche Carrera RS 2.7 1973, as advertised in the used car section of the same magazine from 1979, for DM 16'900.-, so roughly the same money. Today though you would get approximately Euro 150'000.- for the Porsche and maybe 3'000 for a well maintained Audi 80 GLE.

Car seats as a symptom for technology evolution

Modern car seats are engineering masterpieces. The difference between what you get in a modern BMW or Audi to what you had in a Jaguar or BMW in the 50ies or 60ies couldn't be more striking. In the old days car builders did the minimum to allow the drivers seat somewhat comfortable. In sportscars they did even less, often the driver sat basically on the floor of the car or in very rudimentary bucket seats. Since then a lot has happened. Modern seats support the driver by moving electrically, storing seating positions (of more than one driver), can be heated and cooled, and some even do offer a massage to the driver. But there's more. Modern seats also have airbags built inside and they track whether actually somebody is sitting on them. And in some cases seats vibrate to wake up the driver or make him aware that he is leaving the road.
No wonder that modern seats have become much more heavy, probably many hundreds of percentages heavier than seats in the old times. A modern seat can easily weight 30, 40 or 50 kg, or even more, compared to 5 or 15 kg in the past.
But would we want to go back? Probably not, as today we sit much longer in these cars and our back is glad for optimal support. Maybe there's a way to get a bit more from both worlds, some of the lightweight racing seats available in super cars are good examples.

Modern cars causing more accidents because it's so easy to get distracted?

I just read a newspaper article summarizing the problems caused by people using mobile phones or writing SMS while steering a car. Apparently people drunk (0.8) drive better than people using the phone. And writing an SMS increases the risk of an accident by the factor 23. Research teams observed truck drivers moving for 140 m without watching the street while writing an SMS. It's proven that talking on the phone reduces the driver's awareness for the things happening on the street.
What is interesting is that the article points out that one reason that people think they can manage talking on the phone or writing SMS while driving is the fact that operating a car today is so easy and can be so boring. This comes back to what is a regular topic on my blog. Modern cars do so many things on their own that the driver isn't involved anymore into the real driving. The only thing you do in a modern car is steering and pushing break and throttle pedals. Maybe you switch on the indicator now and then but that's it. You don't need to switch on lights or wipers. You don't need to monitor water temperature or oil pressure. You don't need to switch gears or use a clutch pedal. And you don't even need to think whether the next curve actually can be mastered at the speed you are doing because there's a speed limit and that's low enough. And so on. You get the point. And all the driving assistance systems that get added to the cars now make it worse. Soon the only thing you do in a car is deciding when you want to start it. It couldn't be more boring. No wonder people start to use their mobile phone. And modern mobile phones are full-function computers....
So, maybe one of the reaons why there are less accidents caused by classic and vintage cars is that drivers actually focus on what they do, driving the car.

Do we see a decrease in commonality in car control?

You may wonder what the aircraft picture to the left has to do with this car centric blog. Well, here's the point. When you are a civil aircraft pilot at an airline you are typically certified for one aircraft type, for example the B747 (Jumbo Jet). As knowing your aircraft is crucial for safety, the same pilot cannot fly a B747 on one day and let's say a B737 the next day. Because the pilot training and certification process is expensive and the aircraft type orientation reduces flexibility, aircraft manufacturers such as Airbus started to build "commonality" into their aircraft and created groups of aircraft where the same certification applies. So, the same pilot now can fly the Airbus A319, 320 and 321 without being retrained. And even the large A380 follows the same control principles and retraining can be substantially reduced. Aircraft type certification is supposed to make flying more safe because if there's an incident then the pilot knows exactly what to do and doesn't have to think about how a certain procedure works in the specific airplane he is currently steering.
Over 100 years of car manufacturing the commonality between different cars has greatly increased. While some cars had the throttle pedal in the middle in the past, some on the right, today you can take it for granted that the throttle pedal sits on the right, the brake pedal in the middle and the clutch pedal, if there's one, on the left. That's good, as it makes traffic a lot safer. Few people also may remember that Peugeots had the indicator switch on the right side of the steering wheel (LHD car) in the 70ies (and 80ies?) while most other cars had it on the left side. The knob to turn on the lights usually is on the left side of the steering wheel (LHD) for most cars and heating and air control sits in the center console. And the handbrake sits in the middle of the car in the center console usually. At least that was the case in the 80ies and 90ies. There were some exceptions of course, as for example the Porsche had the ignition key on the left side of the steering wheel (LHD) and Saab had it in the center console behind the gear lever. Mercedes didn't use a "handbrake" but rather a foot operated version. But mostly you wouldn't have to read a manual to operate somebody else's car. Now, lately things have changed. Electronic handbrakes, starter buttons and controls in the steering wheel have reduced commonality between different car makes in my eyes. Some of these differences do not affect safety, but some do. It's a step into the wrong direction. Usability has something to do with learning transfer. The smaller the difference to what people are used to the better the usability.

Are vintage race cars and classic cars safe in today’s traffic?

Questions often debated in all kinds of classic car forums circle around safety. How safe is a vintage race car in modern traffic? Can you use a youngtimer or oldtimer safely every day in in today’s heavy and tight traffic? As always these are loaded questions.
Here’s my point to this.
Vintage and classic cars are clearly less safe compared to modern cars in many aspects. They have inferior brakes (narrower and less sticky tires, no anti-lock-breaking, no anti-dive, etc.), there’s no safety cell around the passengers, no pre-calculated demolition impact management and no airbags, often no safety belts, and none of the modern computer controlled safety features such as “EPS”, “ATC”, “pre safe” or automatic breaking. For example, a Jaguar E-Type takes 50-60 meter (or more) to break from 100 km/h to 0, a modern Volkswagen Golf gets this done in less than 40 meters, modern sportscars are approaching the 30/32 meters. That’s a hell of a difference as it means that when the modern sportscar has stopped, the oldtimer behind him still does 60 km/h or so. You wouldn’t want to sit in this car at this moment.
Vintage or classic race cars usually were the best of their breed at a time and often had more safety features than day-to-day cars. But compared to modern cars they still are less safe because of some of the missing features and engineering concepts.
So, does this mean you shouldn’t use them in daily traffic?
I don’t think so. Yes, the cars are less safe by “nature”, but their drivers are much more awake and much less distracted by things like navigation systems, phones and other gimmick. And last but not least, they know about the safety issues and are more careful and look ahead.

The Mercedes 300 SL R107 - an ever green classic car

When Mercedes replaced the famous Pagoda (230 SL - 280 SL, R113) with the R107 many people were disappointed. The new car was heavier, larger and seemed to look less elegant. Despite the not very enthusiastic welcome the R107 series though was built for 18 years (1971 to 1989) and the number of cars delivered to customers was an impressive 237'286. Most of them had 8 cylinder engines (350 SL, 380SL, 420 SL, 450 SL, 500 SL and 560 SL), only 38'879 6 cylinders (280 SL, 300 SL) were built. The 300 SL was introduced in 1985 and built until the end of production of the R107 series. In total 13'443 cars were built.
The reason the car got bigger and heavier than its predecessor was mainly because of increased safety standards. In that aspect the R107 was quite innovative and exemplary. ABS (anti lock brakes) and airbags for examples were on the options list very early.
Looking at the car today it's actually a quite elegant shape and the use of chrome makes it look older than it actually is. The latest R107 SLs just got 20 years old, while the first ones now are almost 40 years old.
When you drive an SL today, the car feels fairly modern despite its age, especially when you have chosen one of the latest cars, as in 1985 the suspensions and the interior were upgraded.
The R107 even had quite an impressive movie career, starring in "Hart to Hart" (driven by Stephanie Powers), "American Gigolo" (driven by Richard Gere), Dallas (driven by Victoria Principall) and visible in many many other productions.
Most of the R107 were delivered with an automatic gear box. Only the 6 cylinders and the 350 SLs could be ordered with a manual gear box. It's estimated that only 10 to 15% of the 300 SLs allow for manual gear shift despite a fuel consumption advantage of 8 to 20% against the automatic thanks to five gears and lower revs.
The silver 300 SL pictured is a 1987 model, equipped with the 4 seat option, passenger side mirror (yes, that was an extra) and radio preparation. Delivered in Germany it has been brought to Switzerland in 2009.
R107 came with a standard hardtop to make the car better usable in the winter or for highway traffic. The picture here shows the three ways you could drive an SL.
Many people say that the R107 was one of the last (if not the last) Mercedes that was built by true engineers not by marketing people. Everything you touch feels solid and the sound of the closing door is unmatched. Even after 20+ years the car feels almost like new and certainly is capable of another 20 years easily. With this and the fact that it has a catalyst on board, an R107 SL may actually be one of the more ecological cars on earth.

Is the end of the car mirror coming?

For many years we are now used to look into our mirrors in our car before we overtake, change lanes or park. We are trained to do so, it was a key element of the car driving exams we had to go through. Interestingly, vintage cars in the early 20iest century didn't have mirrors at all. And it was until the 70ies outside mirrors to become a standard. I can even remember the time when you had to pay extra money for the second (passenger side) mirror. Just as an example the passenger side mirror for a 1987 Mercedes 300 SL (R107) was in the price list for DM 119.70 (roughly 60 Euros). The mirrors also got more and more clever and got for example darker when strong lights were approaching from the back. The also could be electrically adjusted and you could even store their position with a "memory" system. Depending on the driver they readjusted magically.
The outside mirrors though come with a significant disadvantage. They influence aerodynamics in a negative way, increase the drag factor and the overall size of the car. That's why mirrors look quite different today compared to what we were used in the 80ies for example. So there are good reasons to make them very small and in many of the prototypes presented these days they are replaced by small cameras and a display in the car. There are other innovations that help to make driving more secure, for example radar systems that help to prevent the blind spot, making the mirrors less important. So it could well be that future cars won't have outside mirrors any more. It will take some time to adapt to the new systems though. If you have ever swapped from left hand driven cars to right hand driven cars you know what I mean. If the mirror isn't where you expect it you always look to the wrong corner.

Can race car safety be applied to regular consumer cars?

When you watch modern racing then you certainly are impressed by modern safety standards. Formula 1 drivers crash with 200+ km/h into walls and climb out of the car themselves, rallye drivers survive really horrible crashes without any injuries, there has been barely any touring car accident lately with drivers being severely hurt. How is this possible despite the low weight of cars, the lack of airbags and crash deformation zones? There are a number of reasons. The cars are very stiff and have usually a safety cell, there's a roll cage, drivers were helmets and the "HANS" system that stabilizes the head and of course they all have six point safety belts attached very tightly. So if this is making racing all that safe why not apply some of this to our regular cars, the daily drivers. Well, some actually could be applied, but on the cost of convenience and partially also usability. It takes a bit of time for example to attach a six point safety belt and you can't really move in there if you would like to change the CD in your radio. Helmets also are not very convient in normal traffic and a roll cage makes getting into and out of the car quite a climbing exercise. On the other side though safey precautions have made our normal cars very heavy. All these airbags, crash deformation zones, etc. add today some 100 to 300 kg compared to a car two centuries before. So if we were to go for very light cars to bring fuel consumption down then maybe some of the race proven safety means could be applied to daily drivers. Let's see what innovative car manufacturers will be coming up with.

Where has usability gone in car design?

People appreciate all the luxury coming with nowadays' cars. But are they really more usable? I just drove from Berlin to Switzerland, with a Mercedes 300 SL, a car designed at the end of the 60ies, built for 18 years until 1989 and a modern classic car today. It's also an impressive car from a usability point of view.
It starts with the fact that you can see everything, even with the hardtop mounted. You even can see the cover of the trunk when you are going backward. No need for cameras or "park distance control" systems.
The manual is short, really short. All what you need to know to operate the car is covered on less than 60 pages. Have you looked at the manual of the son's son of the 300 SL - the 350 SL built today? You need to read through hundred of pages before you are able to properly adjust the air condition. Actually you can enter and drive the 300 SL from the 80ies without even reading the manual at all, everything is where you would expect it. And there's not that much to fiddle around with anyway. There's no airscarf, no air condition, no ESP, no park distance control, no navigation system, no distance radar, no .... It's basically a car with four wheels. But everything you need for your daily motoring is there, even mirrors that' can be adjusted sitting in the car, the right one electrically the left one mechanically. Good so. The heating can be operated with basically two wheels, you won't need a manual to understand the concept.
And while there may be good reasons that the windows in modern cars are so small, mainly because of passive safety considerations, I prefer the "active" safety of being able to see everything out of the old car, be it children, other cars or a bicycle.
Maybe the designers of modern cars should have a ride in one of these older classics from time to time to have a benchmark on usability.