Saturday, September 19, 2009

Driving mantra Part 2 - Don't use your brakes unless absolutely necessary.

This one is difficult to master if you're a nervous driver who is always on the brakes. What you need to understand is that your tail lights are your only real form of communication with those behind you. If you're constantly tapping the brake - or worse - driving with your foot on the brake all the time - it's like crying wolf. The driver behind you has no indication of if you're really slowing down, or just nervously tapping the brake for no reason. When you do need to stop, everyone behind you is conditioned to think you're just nervously fiddling with the brake pedal again, and that's one way to ensure being rear ended.
So what do I mean by "don't use your brakes"? Simple - take your foot off the accelerator. Your car will naturally begin to slow down. If you're not slowing down enough, then you may use the brake. But if you're in motorway traffic and the brake lights come on in front of you, just take your foot off the accelerator first. Chances are the person in front is a nervous braker. 9 times out of 10, a slight slow down on your part will be all that is needed, and because you didn't brake yourself, you've not amplified the problem for those behind you.
Why drive like this? Well - a good deal of traffic jams are known as phantom or shockwave traffic jams. The traffic is stopped for no other reason than a nervous braker. It works like this - someone gets a bit twitchy and instead of simply reducing their speed with the accelerator, they dab the brake. The person behind them does the same, only a fraction harder. Behind and to the sides, people now see two brake lights so they all begin to dab the brakes a little too. Each dab of the brakes slows down the traffic in that lane by a tiny fraction until suddenly, a kilometre behind you, everyone has come to a complete stop. There's your phantom traffic jam. If you were able to observe this from above, it looks like a shockwave travelling backwards through the traffic. In effect - particles bunching up and pulling apart. Remember the river analogy from part 1 of this series? If you want to see this in a mini simulation, this little java application can be tweaked to show the problem very clearly : A Microsimulation of road traffic. Set it to 'ring road' and watch what happens - you don't need to tweak anything but after a few seconds you'll see a shockwave traffic jam form. Think about this next time you're driving.

Monday, September 14, 2009

Driving mantra - a mini series of blog entries.

After a long and detailed conversation with a movie stunt driver recently, I've been spurred on to write a series of articles which I'm going to publish in the blog over the next few weeks. It will be a series talking about driving skills and how you can do your part to help both yourself and all those around you on the road. This isn't "speed kills" or anything like that, but hopefully a series of bite-sized chunks of information to give you something to think about. It might cover topics you already know about. It might make you think "crap - I do that!" or it might make you think a little more about what's going on when you drive. Either way, I hope you find it useful. Feel free to comment as usual.

Part 1 - Traffic is like a flowing river.
This is the best way to think of traffic. Imagine all the cars are particles of water flowing in a river. If you slow down for no reason, you cause an obstruction like a rock being dropped in the river. Water - the other vehicles - now have to either slow down or go around you, which causes turbulence behind you and to the sides. Turbulence slows down the flow and causes problems. The same is true if you are going to pull out in to traffic - make sure there's enough room or you create a blockage and more turbulence. Apart from your own safety and that of others around you, your sole job is to get from A to B without causing any interruption in the flow of the river.