During the four-day operation, officers are targeting speeding, mobile phone use, seatbelt and motorcycle/helmet offences, alcohol, drug-affected drivers and fatigue.

A 25-year-old Bomaderry man died and another man was critical on Saturday after the car they were travelling in crashed into a tree at Berry.

On Friday, a 91-year-old man lost his life in a four-vehicle crash north of Crookwell and a 34-year-old male motorcycle rider died after he was involved in a crash involving a truck in Riverstone.

Assistant Commissioner Michael Corboy of the Traffic and Highway Patrol Command said he was disappointed with some driver behaviour.

Read more: Woman trapped for 17 hours after South Coast crash

"We have already seen a number of motorists take unnecessary risks on the road this long weekend," Assistant Commissioner Corboy said.

"After the recent wet-weather conditions, we don't want to see an increase in road trauma following the conclusion of this operation," he said.

"Road fatalities have a tragic effect on everyone involved, from the families who must grieve a loved one, to the police who attended the crash, and the communities who have lost one of their own."

"It's simple: slow down and stay alert."

Operation Stay Alert commenced at 12.01am Friday and concludes at 11.59pm Monday, with double demerits in force throughout the period.

Incidents across the state included a 27-year-old woman being stopped for a stationary RBT on Five Islands Road, Unanderra, where she returned a positive result.

She was subjected to a breath analysis which returned a reading of 0.254.

She was served a future court attendance notice for high range PCA and her licence was confiscated.

On the Hume Highway at Sutton Forest, an 18-year-old male P-plater was detected travelling at 165km/h in a 100km/h zone.

His was issued with a traffic infringement notice for motor vehicle exceed speed more than 45km/h and his licence was immediately suspended for six months.