Speeding drivers or those not wearing seatbelts will be slapped with double demerits from Friday, December 21, to New Year's Day, while an extra demerit point will be deducted for all other traffic offences.

The nationally co-ordinated Operation Crossroads, now in its fourth year, will see police step up high-visibility patrols over the Christmas break.

The operation runs from Sunday to January 3, with police promising to keep a watch on arterial roads in and out of the city. There were no deaths on ACT roads over the same period last year, although 11 crashes ended in injury.

The large volumes of traffic on the region's roads make conditions dangerous, according to acting Traffic Operations Superintendent, Rod Anderson.

Superintendent Anderson urged drivers to take care on the roads over Christmas by staying patient and alert in heavy traffic, taking regular breaks and obeying the speed limits.

''People want to travel interstate and go to parties, and see loved ones they haven't seen all year,'' Superintendent Anderson said.

''Sometimes they'll be fatigued, or they'll have too much to drink, just with the volume of traffic on the road.

''We're asking people to slow down, take their time, plan their trip and get there safely,'' he said.

Drivers who misbehave face a loss of licence, hefty fines, the loss of their car, or, in the worst cases, a prison term.

ACT Policing conducted 4500 random breath tests over the last period, detecting 57 drivers over the blood-alcohol limit.