State laws vary but in most states this type of incident would find the other driver not negligence and this incident just a hazard of driving on the roadways. If it was a commercial truck that was loaded with rocks or gravel and they were not tied down properly then you may be able to prove negligence. By proving negligence the other vehicle would then usually be liable for rocks that cracked your windshield.

However if instead a vehicle kicks up a rock from the roadway that then hit your vehicle and broke or cracked your windshield then it would be doubtful that the other driver could be held responsible since that was an unintentional road hazard.

If the passing car kicked up a piece of the roadway, such as a piece of pothole that the state Department of Transportation (DOT) had filled, then the DOT or state may be requested to pay. It would be hard to prove negligence on the part of DOT though just as it would be on the passing vehicle that happen to kick up a piece of gravel lying on the roadway.

Since the other driver is likely to not be found negligent, you would need to make a claim through your own comprehensive coverage to get the crack in your windshield either repaired or replaced.

The deductible associated with your comprehensive coverage would normally be due; however some states such as Florida require insurance companies to waive the deductible for windshield claims. To find out if your state waives the deductible for windshield claims speak with your insurance agent and/or contact your state’s insurance regulator for consumer information.