Matamata-Piako District Council has developed Danger Traffic Zones in commercial and residential areas. It maintains 50 kph speed limit; it has crudely linked misaligned cul de sacs to provide through ways, with dangerous bends and encouraged high density housing increasing traffic over unsuitable roads. Other councils have developed Safer Speed Zones. These are groups of residential and commercial streets with reduced speed limits.
In Hamilton these safer speed zones have speeds reduced to 40 kph and in Christchurch and Wellington to 30 kph. Reduced speed limits logic is simple. Hamilton City Council states the probability of a pedestrian being killed when hit by a vehicle increases from 40 per cent at 40 kph to 80 per cent at 50 kph.
Reduced vehicle speeds also reduces the number of incidents. In 2014 Christchurch Council Research found injury crashes had reduced by 82 per cent across the suburban areas where the speed limit had been lowered to 30kmh, while at the same time, those suburbs with a 50kmh limit experienced a slight increase in injury crashes. The costs of implementing lower speed limits is minimal. It is important that motorists are aware of the changes in speed limits. Signs should be placed at the entrances to each Safer Speed Area both on posts and, in some cases, painted on the road itself. Large billboards are also used to remind drivers as they drive through the areas. Physical works like landscaping and planting, and raised crossings can help with the recognition of speed limit changes. Time costs to drivers are little. Christchurch City Council research found the delay between travelling at 30kmh rather than 50kmh over 275 metres - the longest road length there affected by the speed limit changes - was just 13 seconds.