Ridesharing has taken the world by storm. The conveniences may appeal to you and plenty of others, but the glowing sign in the window should also serve as a warning light.

Cities have seen a rise in severe and deadly accidents with the arrival of ridesharing platforms like Uber and Lyft. The two companies took U.S. passengers across 500 million miles each month in 2016, and there doesn’t seem to be any sign of slowing now that both companies have gone public.

Dangerous intersection ahead

Authors of the study found data by looking at parallel studies, instead of intersecting information. Researchers used statistics from the National Traffic Highway Safety Administration and held it up against increased use of ridesharing in cities across the country.

Uber and Lyft have come out against the results, both saying the study is “flawed,” and they’ve taken extensive measures to combat safety concerns. Just how correct these assertions are is hard to decipher, though, as both companies do their best to keep records out of public hands.

No outlet

Lobbying efforts and protective orders have successfully kept a large number of results out of sight. Important information about dangerous drivers under their banner is kept mostly under wraps, like how many received multiple complaints from riders or caused injuries in accidents.

Cross traffic does not stop

Critics say the companies are slow to remove drivers that pose a threat to customers and other drivers, and the transportation giants are more concerned about their reputation than keeping people safe. Lyft defended their record by saying that millions get to their destination without incident every day. But if you are one of the people sharing the road that aren’t so fortunate, you may have to look elsewhere for help.