Transport trucks in Canada and the European Union have been using speed limiters for a few years now. It’s a great way to increase overall highway safety and doubles as an effective method of increasing fuel economy as well as the overall impact these vehicles have on the environment. But your average consumer cars don’t come with speed limiters installed, so how else is speed controlled?

Of course, we all know about speed limits – those black and white metal signs lining every road in the world do much to help keep us safe. The reasoning is that this one piece of legislation, wherever you happen to be, reduces the difference in speed between vehicles on the same road. Enforcing a common maximum speed limit improves road traffic safety: the World Health Organization lists it as one of the many ways a nation’s legislative body can attempt to reduce road casualties.

Also, a 2003 report from the British Columbia ministry of transport, which studied speed reductions in various places around the globe, showed that reducing speed limits led to a decline in the number of motor vehicle accidents and injuries. At higher speeds drivers have less time to react to changing weather conditions or other unsafe scenarios such as collisions or road construction. By putting a cap on the fastest a car can go, the government, and the police officers that enforce the law, can help increase overall road traffic safety.

In the case where there are no posted speed limits, drivers will often simply “go with the flow.” This is an effect that I argue comes from the fact that there are posted speed limits everywhere. We are used to keeping our speeds relative to those around us. But what is a good rule of thumb for knowing how fast you can drive when there are no posted signs concerning speeds?

In Canada, the general rule of thumb, if you can’t seem to find a speed limit sign on the road you’re driving, is as follows: if you’re in an urban or suburban area you should drive around 40 km/h. Most single lanes and residential area roads are set at this limit and it is a safe speed for those environments. On a multiple lane road (2 or higher), a good rule of thumb is to drive 60-70 km/h. If you are on a highway, the generally accepted practice would be to drive 80 – 100 km/h. But it is always better to be sure about what the speed limit is as going too fast can earn you some demerit points and – as I mentioned here – that’s not something you want to happen.

In addition to being recommended as a way to reduce pollution, fuel consumption and normal wear and tear on a car, speed limits have been shown time and again to reduce road traffic collisions and casualties. There will always be people who don’t obey these signs – I, myself, often find that I’m going around 20 km/h above the speed limit. But even though many people grumble and complain about them, they have proven their worth by forcing us to keep an eye on how quick we’re travelling and will no doubt be here to stay for a long time to come.