Reducing speed allows to reduces the number of accidents by giving more time to the driver to manage its vehicle, and reduces the consequences of an accident by reducing the energy involved in that crash.
In the United Kingdom, the speed limit in towns is usually 30 miles per hour, which is about 50 km/h, and the speed limit on dual carriageways and motorways is usually 70 miles per hour, which is about 105 km/h. In France, the speed limit on motorways is usually 130 kilometres per hour, which is about 80 miles per hour. Also, in United States, most highways are from 65 to 70 miles per hour, and freeways are from 55 to 80 miles per hour. In Canada, the speed limit is usually about 100 km/h. In Australia the speed limit on freeways is between 100 and 120 kilometres per hour, and in towns and cities between 40 and 60 km/h.
Nowadays, in the European Union, speed limit may vary from country to country or from region to region. Typical speed limits are 130 km/h or 120 km/h on rural motorways, between 80 and 100 km/h for rural roads, 70 km/h on point requiring a reduced speed, 50 km/h in main urban roads, and 30 km/h on residential urban areas.
Germany does not have a general speed limit for motorways, but a recommended speed of 130 km/h.