Speed limits on a number of stretches of roadway in Rohnert Park will rise Jan. 1, part of a plan designed to make it easier for police to enforce speeding laws.

The Rohnert Park City Council approved the changes Tuesday after reviewing recent surveys that documented how fast people typically drive on the roads.

Under law, police may only use radar to measure motorists' speeds if speed limits are set according to the surveys, said Public Safety Lt. Jeff Taylor.

Otherwise, officers have to "pace" cars, driving behind them and calibrating motorists' speeds to their own, Taylor said.

The streets where limits are to be changed are:

--Commerce Boulevard between Golf Course Drive and Avram Avenue: from 35 mph to 40 mph.

--Commerce Boulevard between Avram and Southwest Boulevard: from 30 mph to 35 mph.

--Golf Course Drive from Commerce Boulevard to Country Club Drive: from 35 mph to 40 mph.

--Labath Avenue from Business Park Drive to Rohnert Park Expressway: from 30 mph to 35 mph.

--Redwood Drive between Willis Avenue and the southern city limit: from 35 mph to 40 mph.