January 2011
Inappropriate speed contributes to around 14% of all injury collisions, 15% of crashes resulting in a serious injury and 24% of collisions which result in a death and are recorded by the police.
1 This includes both 'excessive speed', when the speed limit is exceeded but also driving or riding within the speed limit when this is too fast for the conditions at the time (for example, in poor weather, poor visibility or high pedestrian activity).
In 2010, 241 people were killed in crashes involving someone exceeding the speed limit and a further 180 people died when someone was travelling too fast for the conditions.
1
Drivers and riders who are travelling at inappropriate speeds are more likely to crash and their higher speed means that the crash will cause more severe injuries, to themselves and/or to other road users. Inappropriate speed also magnifies other driver errors, such as driving too close or driving when tired or distracted, multiplying the chances of these types of driving causing an accident.
http://www.rospa.com/roadsafety/adviceandinformation/driving/speed/inappropriate-speed.aspx