The self-driving cars by the Google X division of Alphabet Inc. have been getting better and improving. However, they still seem to be running with a bit of trouble, which usually ends up with the cars needing to be controlled by human test engineers.

This was revealed last Tuesday through a report filed by the tech giant with the state of California. The report has outlined 272 situations where the software on Google's cars detected a problem that required immediate handling of the cars by human test drivers. Among these incidents, the tech company has analysed that if it has not done so, the incident would have led 13 of the situations to a direct contact with other vehicles or objects.

The filed report also showed the number of disengagements declining significantly during the test period. It shows the disengagement going from once every 785 miles during the testing's first quarter to once every 5,318 miles as of late. These details are required by the state of California to be reported by every automobile manufacturer or supplier testing its autonomous cars in the said state.

And so far, Google has the most extensive number of autonomous cars driving on public roads. The test results, however, shows that Google's autonomous cars, although they have made big improvements, still aren't ready to navigate the roads alone without a test driver jumping into the situation when needed.

The report filed by Google is also reflected by several other reports from other automobile makers and suppliers dealing with self-driving cars. Some of these manufacturers having similar reports include Robert Bosch GmbH and Delphi Automotive PLC; however, they have a higher frequency of interventions. According to Delphi's reports, most of the causes of disengagements involve poor roadway lane markings, construction zones, bright sunlight blinding cameras and erratic behaviour from other drivers.

Meanwhile, the tech giant's recent report seems to drive safety advocates who don't like the idea of introducing self-driving cars to public roads. Google has made its vision in the past known by the public regarding how it wants to build cars in the future that won't require human beings's involvement. But a lot are still sceptical about the idea and are far from accepting a future of human-less cars.