Hi Doctor Diesel!
I was just browsing through the latest issue of Diesel Car, while working on the May issue of Audi Driver over the Easter weekend, and I came across the letter on page 91 relating to electronic parking brakes. I canít comment on the systems used on other marques, but with regard to the EPBs on Volkswagen Group models, it seems to me that many references (as here) totally overlook their primary function, which is not just as a parking brake, but as part of a very effective emergency braking system. Pull on that little switch that “saves so much space on the centre console” and it will pull the car up to a halt with alarming alacrity, and from quite high speeds. Certainly much more so than could ever be achieved with a conventional cable-operated handbrake. Itís all part of the progression towards autonomous driving, slowly adding together components that will eventually allow the car to be driven without human intervention and, of course, the Volkswagen autonomous emergency braking function is able to bring the car to a halt if the driver is incapacitated.
You might have observed that in our road tests in VW Driver and Audi Driver magazines I often draw attention to the position of the EPB switch and warn drivers to keep their passenger’s idle fingers away from them ñ often the EPB switch remains on the left-hand-side of the console, rather than being relocated to the right for right-hand-drive cars. Also, on such models as the Audi A3 Cabriolet, the EPB switch is positioned right alongside the very similar switch for the cabriolet power hood, which can be operated at speeds of up to 31mph. Pull on the EPB switch by mistake at 30mph and youíll certainly know about it! Maybe the car behind will tooÖ?
Neil Birkitt, Editor, Volkswagen Driver magazine
Nice to hear from you Neil! I guess that you’re correct regarding the neglected benefit of the EBP as an emergency brake that’s far more effective than any traditional handbrake ever was. I have often wondered how cars get through the MOT when many handbrakes are so inefficient, but apparently, the efficiency level required is very low. But I do have to confess that I have never been brave enough to try one out in the emergency mode. I really must go out some time and test it at 25mph or something like that, and I guess the anti-lock brakes will prevent anything really nasty happening, like flat-spotting the tyres, although I guess it will be quite a dramatic loss of speed. Am I correct in thinking though that, used on the move, it will employ four-wheel braking, but when used as a parking brake it only operates on the two rear wheels?
You mention the progression towards autonomous driving… something my wife and I were only discussing earlier today. We are both of the opinion that, whilst the concept may be valid on purpose-built roads, or severely modified existing roads, the whole thing will possibly be an unfulfilled dream without massive expenditure on the roads. Take the concept of who gives way to whom, at junctions and roundabouts? How will autonomous driving handle that? How about feeding onto a busy motorway from a slip-road?
I pick on the latter issue particularly as I have had some correspondence with the IAM (now fashionably called IAM Roadsmart) regarding that issue. They have told me that I must, on a jam-packed motorway, still stick to the “two second rule” and create sufficient space between myself and the car in front (50 yards plus at 60mph!) to be able to safely allow any car to enter that space from a slip-road, whilst I then have to re-establish the 50 yards gap between myself and the new car now in front! All of this without offending the drivers of the cars behind me, many of whom will want to overtake me, possibly with a shaking fist, or something even ruder, and then slip into my “safe distance” from the car in front. A totally unrealistic concept one might argue, and yet this is precisely what autonomous cars will be need to be programmed to do, in the cause of safety. That’s an example of why I think the whole idea is rather premature. Manufacturers are spending millions on it, afraid of being left behind, and yet very little money is going towards adapting the roads to the requirements of autonomous driving, or get them back to a safe state, so neglected many of them are. I did a journey in the dark, in heavy rain, last Friday and, frankly, the roads were appallingly lacking in effective or even functional lighting, cats eyes that were reasonably visible, or white lines that were suitably reflective to be of much help at all.
I could go onÖ but put an autonomous car in that same situation, and for safety’s sake, it should/might well have either have pulled up and flashed a dashboard warning saying “not safe to proceed”, or have proceeded so slowly that it was an obstruction to other cars on the road. To drive in the dark with questionable vision (or is it visibility?) is something that we all must do from time to time, in such conditions. On a familiar road you can get home alright. On a strange road, proceeding straight on at a reasonable speed, without the distance of clear forward vision that you really should have, and being ready to take action swiftly when the road suddenly bends, is not really safe driving, I would argue. But we all do it from time to time! As I say, an autonomous car in such conditions, without advanced sensing (radar, ultrasonicÖ?) and other vital road information supplied to it, is going to struggle, because our A- and B-roads are just not suited to the concept! I would be interested in your feedback on the above views! Best regards,
P.S. And what’s going to happen to the pleasures of driving, that many of us still like to enjoy?
All valid points, undoubtedly ñ although some will also argue that, given the erratic/irrational/emotional/aggressive etc. driving of some humans from time to time, or quite often in fact, that autonomous cars canít be any less safe.
Back to the Volkswagen EPB… Yes, it does take something of a leap of faith, and Iíve only ever used it (very carefully, and on deserted roads) up to about 45mph. It is very powerfully progressive rather than ìsnatchyî, and does, as you say, operate full braking effort on all four wheels, as to brake just the rears as powerfully as this would undoubtedly cause a car to spin. Maybe it’s best if not everybody knows about that? Regards,