For Robot Trucks, Navigating Highways Is Just One Bump in the Road

For TuSimple, it was a perfectly-executed maneuver, one the company has practiced repeatedly under mostly ideal conditions on a familiar route. Days before and hundreds of miles away in Cupertino, Calif., a self-driving PlusAI Corp. big rig undertook an even more ambitious operation, merging onto Interstate 280 and into the crush of Bay Area rush hour, and motored on its own cautiously down the clogged highway. The maneuvers on public roads, both short demonstration runs with no commercial cargo on board, show the potential of a technology that has drawn billions of dollars of investment. But they also show how far it has to go before it can operate safely without a human at the wheel, allowing semi trucks to haul themselves over busy interstate highways, through gnarly weather and routes lined with construction. Most startups are pushing to achieve what is known as Level 4 automation, meaning the vehicle is capable of performing all driving functions under certain conditions.