A Porsche 911 will do it in around five seconds. A typical family car will take around 12 seconds given maximum acceleration and the type of gear-shifting speed few ordinary drivers will achieve. Even if the occasional boy-racer did it, they’d almost always be slamming on the brakes immediately to avoid hitting traffic in front of them.
I’ve both driven and cycled along this stretch of road many, many times, and I can’t ever recall seeing anyone do 60mph, let alone 70-80.
Cycle safety is not just about car/lorry speed in my opinion – it’s also about pollution. When you’re exercising, you’re gulping in greater volumes of air – I must applaud the Congestion Charge and hikes in Road Tax pricing but the real problem is the big diesel engines found in lorries and busses. Cutting pollution on the roads is equally important in my view.