One of Ford’s self-driving cars has successfully navigated a winding road at night and without headlights, showing that it can operate without the usual cameras that depend on sunshine and street lamps.
Ford’s self-driving cars typically use a combination of radar, cameras, and light-sensitive radar called lidar to detect—and avoid—what’s around it. The recent test at Ford’s Arizona proving ground showed lidar is advanced enough to operate independently on roads that don’t have stoplights, the company said on Monday.
Get Data Sheet, Fortune’s daily newsletter about the business of technology.
“Thanks to LiDAR, the test cars aren’t reliant on the sun shining, nor cameras detecting painted white lines on the asphalt,” says Jim McBride, Ford technical leader for autonomous vehicles. “In fact, LiDAR allows autonomous cars to drive just as well in the dark as they do in the light of day.”
Lidar emits short pulses of laser light so that the vehicle’s software can create a real-time, high-definition 3D image of what’s around it. Ford’s lidar sensors, which shoot out 2.8 million laser pulses a second, detects nearby objects and uses cues to determine the best driving path.
Ford’s self-driving cars are also equipped with high-resolution 3D maps, which include information about road markings, signs, geography, landmarks, and topography. When a vehicle can’t see the ground, it detects above-ground landmarks to pinpoint itself on the map, and then uses that map to drive successfully in inclement conditions, the company says.
Why Ford hasn’t released self-driving cars:
The successful test doesn’t mean Ford will ditch other sensors. Self-driving cars need as much data as they can process to make them better drivers than humans. But it’s an important early validation of the tech Ford is using—and the company providing it. Velodyne, a longtime partner of Ford, has developed the sensor technology used the autonomous Ford Fusion hybrids.
Ford (F) announced in January plans to add 20 Fusion Hybrid autonomous vehicles this year, bringing the company’s autonomous fleet to about 30 vehicles that are being tested on roads in California, Arizona, and Michigan. Last month, Ford enrolled in the California Autonomous Vehicle Testing Program, which already includes companies like Nissan, Volkswagen, and Google.
The new Fusion hybrids will be equipped with the latest sensor technology from Velodyne. The solid state sensors will be smaller—about hockey puck size—and have a longer range of 200 meters in which they can detect obstacles like trees that they car’s computer system would then know to avoid.