Cadillac’s Super Cruise semi-autonomous driving system is getting a lot more useful as the company will allow it to be used on an additional 70,000 miles (112,654 km) of divided highways in the United States and Canada.

The announcement means models equipped with the system will be able to travel hands-free on more than 200,000 miles (321,869 km) of compatible highways by the fourth quarter of 2019. That’s a significant increase from the 130,000 miles (209,215 km) available right now.

Cadillac says some of new highways will have “limited intersections and traffic control devices” such as railroad crossings, pedestrian crossings, stoplights and stop signs. To cope with these situations, the Super Cruise system will alert drivers to take control of the vehicle when approaching.

Unfortunately, owners of CT6s equipped with Super Cruise will have to take their vehicle into the dealership to receive a software update that includes “performance improvements, enhancements to increase Super Cruise availability and enhancements to the Driver Attention System.” Once the update has been completed, owners will receive the new Super Cruise maps through over-the-air updates which will be sent out later this year.

While Super Cruise availability will remain limited in Canada and the western United States, Cadillac said customers have already traveled 2.5 million miles (4 million km) using the technology. The system is also coming to more vehicles as it will be offered on the 2020 CT4 and CT5.

Unlike traditional semi-autonomous driving systems, Super Cruise only works on highways that have been mapped using LiDAR. This limits where the system can be used, but it’s highly accurate and Consumer Reports said it’s better than Tesla’s well-known Autopilot.