One in six motorists tested for drug-driving in New South Wales returned a positive result over the Easter long weekend, police say.

Officers said they conducted 1,300 tests and caught 222 drivers with methamphetamine, cannabis or ecstasy in their systems.

Assistant Commissioner John Hartley said the figures were shocking.

"One in six is a very high figure - one we're not proud of, we know our average is one in 14," Assistant Commissioner Hartley said.

"We are testing more and more and we'll be testing 48,000 drivers this next financial year, towards 100,000 in 2016.

"We're very concerned over the behaviour this weekend.

"It appears the scourge of drugs is across the whole community, not just in driving."

Assistant Commissioner Hartley said police would triple their capacity to drug test across the state and move equipment to country locations.

Over a wet Easter, three fatal crashes killed four people.

Two cars veered over to the wrong side of the road in the rain, while a pedestrian was struck and killed walking through a 'don't walk' sign in Parramatta.

"Our thoughts and our prayers go the families of those people, but also to the police who attended those crashes and all the other emergency services who tried to help and do what they could to help and to reduce the trauma," Deputy Commissioner Catherine Burn said.

Almost 5,000 drivers caught speeding

Police issued 4,800 fines for speeding over the Easter period, about 400 fewer than the same period in 2014.

One driver, however, was booked driving 80 kilometres above the speed limit.

Deputy Commissioner Burn said the high incidence of speeding, despite education about the dangers, was alarming.

"More than 1,200 people a day, who clearly get the message - they didn't listen, or worse, they didn't care," he said.

Road safety expert Ann Williamson said the decline in road fatalities in the developed world had slowed and new ways to reduce death and serious injury needed to be considered.

Professor Williamson, from the University of NSW's Transport and Road Safety Research Centre, said lower speeds were effective in reducing crashes on high-speed roads, but special designs that forced drivers to slow down worked better on other roads.

Under the new design concept, known as "self-explaining roads", landscaping and design features such as trees and kerbside gardens tend to make drivers slow down naturally.

"Those treatments have been demonstrated to be quite effective at actually achieving what otherwise would have to done by a road rules and more enforcement, to try and make people do the right thing," Professor Williamson told 702 ABC Sydney.