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SPEED LIMITS
Public Works Agency
Roads & Transportation
800 S. Victoria Avenue
Ventura, CA 93009-
GENERAL
The following information is intended to explain the basics of speed limits, summarize the applicable laws, types of speed limits and provide an outline of how and why speed limits are determined.
BASIS FOR SPEED LIMITS AND CALIFORNIA SPEED LAW
The basis of all speed limits is predicated upon the concept that majority of motoring public are prudent and drive at a speed that is reasonable and proper based on roadway conditions, regardless of the posted speed limits.
All states base their speed regulations on the Basic Speed Law which states that: โ No person shall drive a vehicle at a speed greater than is reasonable or prudent having due regard for weather, visibility, the traffic on, and the surface and width of, the highway, and in no event at a speed which endangers the safety of persons or property โ (CVC 22350).
TYPES OF SPEED LIMITS
Speed limits are classified as advisory or regulatory. Advisory speed limits signs which appear with yellow background, are commonly placed as part of warning signs for roadway conditions that would require slower operating speeds than the legal speed limits. It is often not enforced except when the conditions make it unsafe to drive faster than the advisory speed limits in violation of the basic speed law.
Regulatory speed limit signs or prima facie speed limits are the legally enforceable speed limits established statutorily (by state law) or modified through an engineering and traffic study (ETS).
The most common prima facie speed limits established by law in California are:
- 65 mph maximum limit on freeways; or 70 mph when posted
- 55 mph on two lane undivided highway or when towing a trailer
- 25 mph at school zones when children are present
- 25 mph on local streets within residential districts and business districts.
- 15 mph on alleys
- 15 mph on blind intersections or railroad crossing that is not controlled by gates or traffic signal
Most speed limits that are set by law are enforceable regardless of lack of posted signs. This is why speeding on residential streets is an enforceable citation even though there are no posted 25 mph signs. The majority of roadways within the County do not have posted speed limits but have a legal maximum speed limit of 55 mph.
A lower speed limit, below this legal maximum speed limit, may be reduced if justified on the basis of an engineering and traffic survey (E&TS) (CVC 22358). Such surveys include an analysis of roadway conditions, accident records, and a sampling of the prevailing speed of traffic (CVC 627).
WHAT ARE SPEED TRAPS?
A speed trap is created when the reduction of the speed limit on the roadway below the maximum speed limit was not made based on an E&TS and does not conform to the guidelines for the reduction of speed limits as set by the California vehicle code.
Citations issued where a speed trap is found to exist are likely to be dismissed, particularly if radar enforcement methods are used (CVC 40803 โ 40805).
ENGINEERING AND TRAFFIC SURVEY
In conducting an E&TS, speed limits are normally set at a five-mile-per-hour increment nearest to critical or 85th percentile speed or the speed at which 85% of the motoring traffic is driving at or slower. For example, if the 85 th^ percentile speed is 37 mph, then the speed limit should be posted at the nearest 5-mph increment which is 35 mph. Further, a one-time 5-mph reduction to 30 mph may be allowed for conditions that are not apparent to motorists such as higher than expected crash rates, bicycle and pedestrian activities and other factors documented in the E&TS.
COMMON MISCONCEPTIONS ABOUT SPEED LIMIT
Four widely held misconceptions about speed limits are:
- Speed-limit signs will slow down traffic;
- Speed-limit signs will decrease accidents and increase safety;
- Raising a posted speed limit will increase the speed of traffic; and
- Lowering a posted speed limit will automatically decrease the speed of traffic.
However, several studies have consistently shown that there are no significant changes in average vehicle speeds following the posting of new or revised speed limits.
Similar research has found no direct relationship between posted speed limits and crash frequency.
