Google’s self-driving car project took its worst vehicle crash on Friday, without injuries.

A van used by Interstate Batteries ran a red light and side struck a Lexus RX 450h hybrid crossover SUV retrofitted by Google for its self-driving car project. Google employees were riding in the car, and sat “dazed” but uninjured while waiting for a tow truck in Mountain View, Calif.

The autonomous test vehicle’s traffic “light was green for at least six seconds before our car entered the intersection,” according to a Google statement.

Google’s self-driving cars have been in several crash incidents since the test run started in 2009. Until this latest crash, there had only been a series of slight crashes, usually with the autonomous car’s back-end being hit while slowly turning a corner.

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Unlike Tesla, now under investigation for two fatalities and other crashes potentially tied to its Autopilot system, Google has only been blamed for one collision. In late February, a Google self-driving Lexus SUV drove into the side of a bus at low speed, according to a California Department of Motor Vehicles filing.

One criticism of Google’s 1.5 million-plus miles of test driving is that the self-driving car is driving much slower than cars typically travel. That can cause fender-bender dings while the human driver turns right, looking to the left for oncoming traffic and having expected that the Google car would have turned right at a normal speed.

As the Fortune article describes, the Friday crash points to a much larger challenge that the self-driving car revolution faces. These advanced technology cars will be sharing roads with human drivers for several years.

A recent Goldman Sachs report forecasts that it will take until 2060 for vehicles registered to operate in North America will have full automation. Attention will be given to avoiding these types of crashes as more autonomous vehicles show up and face danger from human drivers.