mpaton2004 wrote:
Thanks! Exactly the point! If COMPETENT drivers will be maintaining that sort of speed ANYWAY, we therefore can eliminate the WORST drivers' choice of speeds with the system as under no circumstances is it neccessary to travel above 10-15 mph in the first place under even the best conditions.
They would not need to stare at the speedo
They would be able to focus 100% of the time outside the vehicle
There would be no speed cameras
The environment would be consistent
We are at the lower extremes of the Joksch curve for fatality probability.
And at the same time remove all incentive for the "worst" drivers to improve; after all if you are driving at 15mph it has to be safe doesn't it?
The other little problem with the idea is that those with responsibility for setting the areas will immediately start with "scope creep", and extend the areas, after all why bother with equipment to set the limit at each end of each road like this (hundreds and possibly thousands of them) when you could for a much lower cost just put them onto all the access roads into the town (20 or 30) and apply a blanket limit across the entire town? Red Ken is already shifting CG out of central London so it will happen - there is no chance in hell that such an idea will be limited to residential streets.
And another little problem is how is it supposed to work for all vehicles? Modern ones with ABS sensors that can give actual road speed and an EMU that can limit engine revs - then technically possible, but what about all the older mechanical ones? What about cyclists - how do we restrict the lycra-clad maniacs (
) to a pedestrian 15mph? And won't they be more vulnerable given that they and the vehicles around them are going exactly the same speed? Is anybody allowed to overtake say a milk float going at 12 mph?
Which leads onto the next little problem - speed differentials - even the idealised ABS sensor based mechanism is dependent on the size of the wheels - new tyres are larger than worn tyres, so two identical cars with different tyre wear will give different limited speeds - the new tyred one will be going that little bit faster, and then it's driver can no longer sit on the limiter, but has to take manual control.
What about those areas that are not blessed with flat as a pancake geography? The only way to ensure a speed as low as 15mph in a hilly area (e.g. Leek in Staffs which has many such roads) is to have machine controlled braking as well. So we are not just talking about a simple black box, but are instead proposing full vehicle control - why not just throw in optical and radar sensors too - at least they will be able to give accurate speed based on doppler readings, and maintain the safe distance to the vehicle in front. Bargain price of £5000 per vehicle and compulsory scrapping of all vehicles to which it cannot be applied. Still there would be a healthy black market in bypass mechanisms!