New research shows that accidents involving vehicles merging into other traffic lanes in metropolitan and greater Sydney have increased by 11% over the past three years.

NRMA Insurance says the Homebush Bay Drive area saw the greatest increase in merging accidents, with a 56% rise over the past three years.

The company says merging accidents account for an average of 7% of all claims in the Sydney area.

An audit by NRMA found 73% of 124 merging locations in Sydney had incorrect, poorly located or missing signage.