Speed and lane questions often present several numbers or several plausible positions. Apply the most specific road, vehicle and condition rule first, then check whether safety requires an even lower speed or a different lane.
Build a hierarchy before choosing a speed
California's general statewide maximum is 65 miles per hour unless another maximum is authorized and posted. A narrower road-type rule generally sets 55 miles per hour on an undivided highway with no more than one through lane in each direction, unless a higher maximum is authorized and posted. Both figures are ceilings, not targets. Weather, visibility, traffic, road surface and road width feed the basic speed law. If those conditions make the posted number unsafe, select a lower speed that is reasonable or prudent and never endangers people or property.
| Step | Decision |
|---|---|
| Road maximum | Identify the statewide, road-type or specifically posted ceiling that applies. |
| Current conditions | Lower speed when rain, visibility, traffic or the road makes the ceiling unsafe. |
| Traffic position | When moving below the normal speed of traffic, use the right-hand lane or stay as close right as practicable unless an exception applies. |
| Bicycle pass | Protect clearance first, then test whether the conditional lane change is required. |
| Crosswalk approach | Keep the vehicle outside the applicable daylighting distance. |
Lane position uses a different comparison: your speed against the normal speed of traffic. A slower vehicle generally belongs in the right-hand lane or as close as practicable to the right edge, except while passing, preparing for a left turn or within another statutory exception. Do not weave each time a faster vehicle appears; choose the lawful position and make deliberate safe changes.
For a bicycle proceeding in the same direction, maintain a minimum three-foot gap between every part of the motor vehicle and the bicycle or its operator. The lane-change branch applies when the bicycle is in the same lane and another same-direction lane is available: change lanes when doing so is practicable, lawful and safe. If traffic or roadway conditions make those requirements impossible, slow to a reasonable and prudent speed and pass only when the movement will not endanger the bicyclist. This fallback is not permission to squeeze past at the posted speed.
For crosswalk daylighting, measure from the vehicle-approach side. In the ordinary setting without an applicable exception, remain at least 20 feet away. Where a curb extension is present, the figure is 15 feet. A shorter remembered distance does not replace either branch.
The traps
- Holding the far-left lane while moving below the normal speed of traffic. Without a passing, left-turn, or other exception, slower traffic generally keeps right.
- Weaving between lanes whenever a faster vehicle appears. The rule points slower traffic to the right-hand lane or as close right as practicable; it does not call for repeated lane changes.
- Using a 10-foot daylighting distance. In the ordinary no-exception setting, the vehicle stays at least 20 feet from the approach side of the crosswalk.
- Using 15 feet when no curb extension is present. Fifteen feet belongs to the curb-extension setting; the ordinary distance is 20 feet.
Try it
Heavy rain sharply reduces visibility and traction on a road posted at 65 miles per hour. What does California's basic speed rule require?
- Maintain exactly 65 because a posted limit overrides weather
- Drive at least 55 so traffic does not slow
- Reduce speed as needed to remain reasonable and prudent
- Stop in the travel lane whenever rain begins
A driver is overtaking a bicycle traveling in the same lane and direction. Another same-direction lane is available, and changing into it is practicable, lawful, and safe. Which actions are required? Select all that apply.
- Keep at least three feet between the motor vehicle and the bicycle or rider
- Sound the horn continuously until the bicycle leaves the lane
- Change into the available same-direction lane for the pass
- Stay in the same lane at the posted speed because the lane change is optional