What is Motorcycle Lane Splitting in California?

California is the only U.S. state to explicitly legalize lane splitting, where motorcyclists ride between lanes of stopped or slow-moving traffic. This practice, governed by specific laws and safety guidelines, contrasts with other states’ more restrictive approaches, such as lane filtering. This article explores California’s legal framework, safety recommendations, and the broader national context.

California’s Legal Framework for Lane Splitting

Core Statute: California Vehicle Code Section 21658.1

• Definition: Lane splitting is defined as a two-wheeled motorcycle riding between rows of stopped or moving vehicles in the same lane, on divided or undivided streets, roads, or highways.

• Authority: The statute authorizes the California Highway Patrol (CHP) to develop educational safety guidelines.

• Collaboration: The CHP must consult with agencies like the Department of Motor Vehicles, Department of Transportation, Office of Traffic Safety, and motorcycle safety organizations.

General Traffic Law: California Vehicle Code Section 21658

• Requirement: Vehicles must stay within a single lane as much as practical and only change lanes when safe.

• Judicial Interpretation: In People v. Butler (81 Cal.App.3d Supp. 6, 1978), the court clarified that drivers must:

  1. Stay within a single lane.

  2. Ensure lane changes are safe.

• Implication: Motorcyclists must prioritize safety during lane splitting, aligning with broader traffic safety principles.

CHP Safety Recommendations

The CHP provides non-binding guidelines to enhance lane splitting safety:

1. Speed Differential:

   • Limit motorcycle speed to no more than 10 mph faster than surrounding traffic.

   • Higher differentials increase accident risks.

2. Traffic Conditions:

   • Safer in slow-moving or stopped traffic.

   • Avoid lane splitting in high-speed or congested conditions with sudden speed changes.

3. Lane Width:

   • Only lane split when there’s enough space to pass safely.

   • Narrow lanes increase collision risks.

4. Motorcyclist Skill:

   • Requires advanced handling and traffic awareness.

   • Novice riders should avoid lane splitting until proficient.

5. Vehicle Positioning:

   • Stay predictable and visible.

   • Avoid blind spots and monitor surrounding vehicles’ signals and mirrors.

6. Environmental Factors:

   • Avoid lane splitting in adverse conditions (rain, fog, darkness) due to reduced visibility and traction.

7. Specific Locations:

   • Exercise caution or avoid lane splitting near freeway ramps, intersections, or construction zones due to unpredictable traffic and narrow lanes.

8. Respect and Awareness:

   • Motorcyclists should ride courteously, avoiding loud exhausts or aggressive behavior.

   • Drivers should watch for lane-splitting motorcyclists and avoid sudden lane changes.

National Landscape: Lane Splitting vs. Lane Filtering

While California broadly permits lane splitting, other states have adopted lane filtering, a more limited practice typically allowed only in stopped or slow-moving traffic at low speeds. Key examples include:

• Arizona:

  • Allows lane filtering when traffic is stopped, on roads with two+ lanes in the same direction, speed limit ≤ 45 mph, and motorcycle speed ≤ 15 mph.

  • Prohibited on shoulders, medians, freeways, or interstates.

• Utah:

  • Permits lane filtering on roads with speed limits ≤ 45 mph, motorcycle speed ≤ 15 mph, when traffic is stopped, on roads with two+ lanes in the same direction.

• Montana:

  • Allows overtaking stopped or slow-moving vehicles (≤ 10 mph) if lanes are wide enough and conditions permit safe operation.

• Hawaii:

  • Permits “shoulder surfing” to pass stopped vehicles on roads with two+ lanes in the same direction.

• Colorado (effective August 2025):

  • Allows lane filtering when traffic is stopped, motorcycle speed ≤ 15 mph, on roads with two+ lanes, but not on the rightmost lane.

• Minnesota (effective 2025):

  • Permits lane filtering with motorcycle speed ≤ 25 mph and speed differential ≤ 15 mph from stopped or slow-moving traffic.

Key Distinction

• Lane Splitting (California): Allowed in both stopped and moving traffic at varying speeds.

• Lane Filtering (Other States): Restricted to stopped or very slow traffic, with low-speed limits.

Conclusion

California’s lane splitting framework, rooted in Vehicle Code Sections 21658 and 21658.1, and reinforced by People v. Butler, promotes responsible practice through clear laws and CHP safety guidelines. As other states adopt limited lane filtering, California remains the benchmark for lane splitting. Understanding these laws, safety recommendations, and national variations is critical for safe and legal motorcycle operation across the U.S.