Merges, Lane Changes, and Who Pays

Southern California driving involves a lot of merging — long on-ramps, dense traffic, and interchanges that ask you to cross several lanes in a short distance. In the calls our office takes, lane-change and merge incidents are among the most common ordinary collisions.

The hard ones are the interchanges that ask for several lanes in a short distance: the 5 and the 405 separating in Irvine, the 91 through the 71 and 241 junctions at Corona. Add left-hand exits and lanes that simply end.

What usually decides fault

The core question is which vehicle was changing lanes and whether that movement could be made safely. A driver moving laterally into occupied space generally carries the responsibility, though real incidents get complicated by speed differentials, sudden braking ahead, and drivers who accelerate to close a gap.

Two sections carry that. Vehicle Code section 22107 says no person shall move right or left upon a roadway until the movement can be made with reasonable safety, and then only after an appropriate signal. Section 22108 measures it: continuously during the last 100 feet. Together they put the burden on whoever moved sideways.

Why these claims get disputed

Because both drivers usually feel wronged. Damage patterns often sit along the sides of vehicles, which tells a less obvious story than a rear-end impact. This is exactly the situation where roadside photographs earn their keep — positions, damage locations, lane markings, and the wider scene.

The coverage that matters

If the other driver is at fault, their liability coverage is the first place the claim goes. If they're uninsured or minimally insured, uninsured motorist coverage is what stands in — and given that industry estimates have long put roughly one in six California drivers on the road without insurance, that's not a remote scenario here.

Underinsured motorist coverage deserves its own sentence: in California it is built to make up a difference rather than to stack on top of the other driver's limits. Have an agent walk through your own numbers.

The practical habits

Signal early enough to be seen. Check the mirror and the blind spot rather than one or the other. Match speed before moving, not during. Plan interchange exits before you're in them rather than crossing three lanes at the last moment.

If it happens

Exchange what Vehicle Code section 16025 requires, photograph everything, get witnesses, and report to your insurer promptly. And make sure your uninsured motorist coverage exists before you need it.

The merge where nobody touches anybody

One version comes up often enough to plan for. A driver crosses into your lane, you brake or steer away, and you end up in the barrier or spun into somebody else, while the driver who caused it carries on and never knows. No paint transfer, no plate, no second party at the scene: one of the hardest claims to prove even when everyone believes you.

Two things decide it: witnesses, which means asking the drivers who stopped for a name and number before they leave, and video, since a dashcam earns its price here and almost nowhere else. How your uninsured motorist coverage treats a no-contact incident is specific to the policy language. Ask while nothing has happened.