Gravel trucks, US 52 and the rock chips Winston-Salem drivers pick up

Where the stones come from

Most chips are not caused by a rock falling off a load. They come from tires. Gravel collects on shoulders, at the edge of work zones and at on-ramps, and a tire picks a stone up and flicks it backward. The stone climbs, slows and drops, and the windshield behind is in its way.

Loads are the other source, and North Carolina law addresses them directly. Under G.S. 20-116(g), no vehicle may be driven on a highway unless it is loaded to prevent any of its load from ‘falling, blowing, dropping, sifting, leaking, or otherwise escaping’. Trucks over 7,500 pounds carrying rock, gravel or stone must keep the load six inches below the walls and have it ‘securely covered by tarpaulin or some other suitable covering’. A covered load still leaves stones stuck on the tailgate and the bumper, which fall off at the first bump.

How to cut the odds

• Leave more room behind trucks. A stone loses height and speed with distance; the extra car length is the single biggest help.
• Change lanes away from gravel loads and from trucks leaving a quarry or a construction site.
• Watch work zones. Loose gravel builds up at lane shifts and temporary ramps. Slow down and give the car ahead more space.
• Do not follow a truck onto the shoulder. That is where the loose stone is.
• Keep your wipers in good shape. Worn blades drag grit across the glass; NC’s safety inspection checks the wipers in any case.

Why highway chips spread faster

A stone that hits at highway speed tends to leave a deeper break with longer legs than one that hits in town, and the car then goes straight back to highway work: vibration, wind pressure on the glass and, on a hot day, cold air from the vents on the inside of a sun-warmed windshield. Those are the conditions that make a chip run. That is why a chip picked up on I-40 in the morning can be a crack by the evening commute, and why a quick repair is worth arranging the same week.

Look at the chip from inside the car as well as outside. If you can see a line starting from one edge, or if the chip sits right in front of the driver, mention it when you ask for a quote: both change what can be done.

After the stone hits

Pull over when it is safe and look at the damage. If there is a chip with no lines running from it, put clear tape over it to keep out dirt and water, and keep the defroster and air conditioning off the glass at full blast until it is fixed. A chip the size of a pea is a quick resin repair now, and the windshield stays in the car. The ROLAGS repair standard treats stone breaks up to two inches in diameter as repairable; in practice the smaller and fresher the chip, the better the result.

The longer it waits, the likelier it is to run. Temperature swings and bumps do the rest. Our page on windshield repair in Winston-Salem explains what can be filled and how the repair is done at your car. If a line has already run out from the chip, read windshield crack repair in Winston-Salem.

Can you claim against the truck?

In practice it is hard. You would need the truck’s details and evidence the stone came from its load rather than off the road surface. Most drivers instead use their own comprehensive coverage: the NC Department of Insurance lists ‘missiles or falling objects’ and ‘breakage of glass’ among comprehensive losses, paid less your deductible. A chip repair often costs less than the deductible, which is one more reason to fix it while it is small.

Questions people ask