Engineering Traffic Speed Surveys

The City of Roseville sets speed limits through an engineering and traffic survey in accordance with standards set by the State of California.  For streets that carry local traffic only, the speed limit is set at 25 mph and is not posted.  The purpose of this web page is to publish the engineering and traffic surveys for major streets, prepared and reviewed regularly by the City of Roseville in accordance with the California Vehicle Code.

Engineering and traffic surveys measure the actual speeds that drivers travel on a given street.  Certified lidar guns are used to ensure that the measurements are accurate.  To the extent possible, the speed measurements are taken on days with fair weather, dry pavement, and clear visibility and are taken at a location not affected by stop signs, parks, schools, curves or other features that would affect speed. An effort is made to ensure that the presence of lidar survey equipment did not affect the speed of the traffic being surveyed. After the data on actual speeds has been analyzed, the speed limit is normally set at or below the speed at which 85 percent of drivers are driving.  Speed limits cannot be set arbitrarily low, as this would create violators of the majority of drives and would not command the respect of the public. 

An engineering and traffic survey is to be reviewed five years after it has been completed.  If, at the five year point, the City Engineer finds that conditions have not changed, it does not need to be reviewed for another two years.  If, when the engineering and traffic survey is reviewed seven years after it has been completed, it does not need to be reviewed for another three years.  A new engineering and traffic survey must be completed at the ten year mark.  The files below provide the engineering and traffic surveys for all of the major streets in Roseville.  Follow the links to download the latest engineering and traffic survey. 

Speed limit misconceptions
When traffic problems occur, concerned citizens frequently ask the city to lower the speed limit. There are widely held misconceptions that speed limit signs will slow the speed of traffic, reduce accidents, and increase safety. Most drivers drive at a speed that they consider being comfortable, regardless of the posted speed limit. 'Before and after' studies have shown that there are no significant changes in vehicle speeds following the posting of new or revised speed limits. Furthermore, research has found no direct relationship between posted speed limits and accident frequency.