Four fatalities in a day, too many: police

After four people died in separate crashes across the state over 24 hours, NSW Police are urging motorists to think about Fatality Free Friday.

Three people died in road related collisions in Sydney on Thursday - at Londonderry, Mooney Mooney and Neutral Bay.

A fourth person died on Thursday after a Land Rover rolled over on a property at Marulan, in the southern tablelands.

Fatality Free Friday, held on the last Friday of May, is an initiative of the Australian Road Safety Foundation.

Traffic and Highway Patrol Command's Superintendent Stuart Smith said risky on-road behaviour needs to be curtailed.

He said the public need to understand that using the road isn't just about themselves it is about other road users.

"We are talking clearly about those road behaviours, about travelling too fast on the road, drink and drug driving, not wearing your seatbelt, not wearing your helmet and the new phenomenon of driving with a mobile phone, and certainly fatigue."

Fatality Free Friday will be May 30.