City of Pleasanton Speed Limits

Speeding carries more consequences than just traffic tickets; it can be deadly. Striking a pedestrian on the roadway can result in death. It is always important to keep alert and maintain enough distance from obstacles, pedestrians, and other vehicles to come to a complete stop.  The faster a vehicle travels, the more distance it will need to come to a complete stop.

Figure: Likelihood of Pedestrian Death vs Speed. Adapted from Impact Speed and a Pedestrian's Risk of Severe Injury and Death by The AAA Foundation for Traffic Safety, 2011.

An Engineering and Traffic Study is commonly referred to as a speed zone survey or a speed survey. A speed survey is the tool we use to determine the speed limit for a particular section of roadway. Speed limits provide notice to drivers of the maximum speed limit on a roadway and assist police in separating violators from the reasonable majority. Roads are typically split into sections with similar physical attributes. Please note that not all roadways are required to have speed surveys to determine the speed limit.

Surveys begin with a description of the roadway: physical attributes of the road including what roadside development is present. The number of lanes, length, and road curvature are described in this section.  Surveys also include a map of the road segment and a description of what bicycle and pedestrian facilities are provided.

After the description of the roadway, the prevailing speeds are given. The most important number is the called either the critical speed or the 85th percentile speed. This speed (we refer to it as the critical speed) is the speed at which 85 percent of the vehicles sampled travel at or below. For example, if the critical speed for a segment of roadway is determined to be 37 MPH , then 85 of every 100 vehicles travel at or below 37 MPH.

The speed limit is set through the examination of the critical speed (85th percentile speed). State and Federal law requires that the speed limit is set at the 5 MPH increment closest to the critical speed.

Also included in this section is the 50th percentile speed, or median speed. This is the speed at which 50 percent of the vehicles sampled are traveling at or below. The 10 MPH pace speed is also listed. The pace is the 10 MPH speed range with the largest percentage of vehicles. These two metric have been used in the past to set posted speed limits.

The latest two years of collision records are also reviewed to determine a collision rate. This rate is calculated in collisions per million vehicle-miles traveled. The million vehicle miles scale is used to make the rates easier to understand.  A segment’s collision rate is then compared to an average of similar roads in Pleasanton.

The next section discusses elements a driver may not realize about the segment being traveled. These elements include higher than average collision rates, pedestrian/bicyclist patterns, nearby bicycle/pedestrian generators including schools or parks, nearby senior housing or facilities, limited sight distance, any hidden driveways, etc.

Finally, the recommended speed limit (this is the posted speed limit) can be found near the end of the speed surveys. As mentioned above, the limit is set based on the speed of 85% of the drivers. A 5 MPH speed limit reduction is allowed at locations with conditions not readily apparent to the driver or the collision rate is high and a speed reduction would improve the collision rate. Here are two examples of this process: If a critical speed is 32 MPH, the law requires that the speed limit is set at 30 MPH.  If there were unusual conditions not readily apparent to the driver that warranted a 5 MPH reduction in the speed limit, the speed limit may be legally reduced to 25 MPH. If a critical speed was 33 MPH the law requires that the speed limit is set at 35 mph.  If there were unusual conditions not readily apparent to the driver that warranted a 5 MPH reduction in the speed limit, the speed limit may be legally reduced to 30 MPH.

School zones are located within 1,000 feet of a school. The speed limit in a school zone is 25 MPH while children are present either during school hours or during the noon recess period.

There is a 25 MPH limit on residential or business roads, even when a speed limit is not posted.

Advisory speed limits are usually established for one curve or a short segment of roadway where conditions are not safe for the 85 ^th  percentile speed. These limits are indicated by black and yellow diamond signs. Advisory limits are located near conditions like curves, hidden driveways, and hills.

It is important to slow down in the dark to watch for animals, pedestrians, disabled vehicles, or obstacles in the roadway.

Weather conditions like rain, fog, and wind affect how fast a vehicle can safely travel. When a roadway is wet, a vehicle requires more distance to come to a complete stop. A driver should travel slower to have enough time and distance to stop safely. At high speeds in heavy rain conditions, hydroplaning can also occur. When a driver cannot see due to fog or rain it is best to slow down or pull over until conditions improve.

“California's ‘Move Over’ law requires all drivers to move over a lane or, if they are unable to do that safely, slow down when they see flashing lights on Caltrans vehicles, law enforcement and emergency vehicles, and tow trucks,” (Department of Transportation).

In addition, new California law (in effect 1/1/23) requires that a vehicle overtaking a bicyclist move to an adjacent lane, if one is available, before passing. It’s also advised to move over for construction work, disabled cars, or pedestrians in the roadway.