I have been reading with interest and shock that Transport for London is looking at the idea of Speed curbing - also known as intelligent speed adaptation (ISA). Bar the obvious reduction in speed camera fines I can only see pitfalls. I use a SatNav and when I accelerate on a motorway slip road I often get a warning that I am over the speed limit as it thinks I am in a 30 mph zone. This could prove lethal if I was limited with the Speed Curbing device as I would not be able to integrate easily in to the motorway traffic. Often accelerating beyond the speed limit, for a very short period, to pass a lorry on a motorway or 'get out of trouble' like when trying to get out of the blind spot of a vehicle merging from the left can be life saving. What would happen in temporary speed limits for road works? Would all cars automatically break the same when going from a 50 to a 30 mph limit? I can see lots or rear end shunts when one model breaks harder than another as the driver has had their sensation of speed taken away from them because the computer is controlling the cars speed. I also fear that would drivers to 'shut off' mentally and let the car do the thinking. What people need to do is be more aware on the roads. I don't constantly look down at my speedometer to check my speed, I have an awareness of my speed and I am usually correct give or take 2 - 4 mph. A reader the other week commented that they'd now only drive at 50 mph on the motorways to avoid a speeding fine, if they can't tell which side of the speed limit they are by 20 mph they should not be allowed on the road. If drivers were to concentrate more on the roads rather than being on mobile phones, changing CD's, smoking or whatever else it is that distracts them we'd have safer roads.