Motorcycle merging accidents typically occur when a driver fails to properly check for motorcycles before changing lanes or merging onto a roadway. The most common cause is blind spot negligence—drivers who rely solely on their mirrors without physically turning to check their blind spots often miss motorcycles traveling alongside them. This is particularly dangerous because motorcycles have a smaller profile than cars and can easily disappear from a driver's peripheral vision.
Another frequent cause is speed differential misjudgment. Drivers often underestimate how quickly a motorcycle is approaching, especially on freeways where motorcycles may be traveling at higher speeds. When a driver merges into traffic without accounting for a motorcycle's actual speed, they create a dangerous situation that leaves the rider with little time to react. Distracted driving also plays a significant role—drivers texting, adjusting their GPS, or engaging in other distractions may merge without properly scanning for motorcycles.
Inadequate signaling or failure to signal altogether compounds these problems. California Vehicle Code Section 22107 requires drivers to signal their intention to merge or change lanes at least 100 feet before the maneuver. When drivers fail to signal, motorcyclists have no warning of the impending lane change and cannot take evasive action. Additionally, aggressive driving behaviors such as sudden lane changes, weaving through traffic, or merging at unsafe speeds create hazardous conditions for all road users, but especially vulnerable motorcyclists.