Traffic

Stop Signs

A stop sign's  primary purpose is to control the right-of-way of an intersection.  Studies have shown that it is not an effective tool for controlling the speeds of vehicles, as it may lead to vehicles rolling through stop signs and even speed up after the stop sign to account for lost time.  Stop compliance is low at locations where the stop sign does not meet the warrant criteria (below).

The California Manual on Uniform Traffic Control Devices (CA MUTCD) establishes the criteria in which stop signs are installed. In summary, the criteria are dependent on the number of collisions within a 12-month period, minimum vehicular/pedestrian/bicycle volumes on the major street and minor streets, and other engineering factors (geometry of the intersection, nearby high generation of pedestrians, etc.).

Speed Bumps

Speed bumps are not installed on public streets in Foster City because they cause damage and increase the emergency response times for emergency vehicles.

Speed Limits

The speed limits of roads are established by the Engineering and Traffic Survey (ET&S).  The ET&S consider the following in establishing the speed limit of a given road:

• 85th-percentile speed.  The 85th-percentile speed is the speed at or below which 85 percent of vehicles travel at on a given road on an average day.  This is the speed in which most motorists driving the road consider safe and reasonable.
• Collision history
• Highway, traffic, and roadside conditions not readily apparent to the driver.

The speed limit is established at the nearest 5 mph increment of the 85th-percentile speed.  The California Vehicle Code (CVC 627 and 22358.5) allows jurisdictions to reduce the posted speed limit by 5 mph from the nearest 5 mph increment of the 85th-percentile speed. If the 85th-percentile speed requires rounding up, then the speed limit may be rounded down to the nearest 5 mph increment below the 85th-percentile speed (CVC 21400(b)) but shall not reduce the speed limit any further for any reason.

Traffic Inquiries

If you have any questions,  please contact Public Works by email at publicworks@fostercity.org or by phone at (650) 286-3270.