It's Not A Mystery: Why Tesla Autopilot Didn't Stop For Emergency Vehicles

Tesla Inc TSLA along with 12 other auto manufacturers including Ford Motor Company F and General Motors Company GM are under investigation by the NHTSA in regards to driver assist systems and accidents involving first responder vehicles.

What happened: In a recent Los Angeles Times article titled "A Tesla mystery: Why didn't auto-braking stop these crashes," the question is asked why Tesla's Autopilot or Traffic Aware Cruise Control (TACC) do not stop for emergency crashes.

It is not just a Tesla problem, as NHTSA's investigation shows; the answer is directly in the owner's manual from Tesla, Ford and other vehicles.

The Tesla Model 3 owner's manual states:

WARNING: Traffic-Aware Cruise Control cannot detect all objects and, especially in situations when you are driving over 50 mph (80km/h), may not brake/decelerate when a vehicle or object is only partially in the driving lane or when a vehicle you are following moves out of your driving path and a stationary or slow-moving vehicle or object is in front of you.

The Ford Mach E owner's manual states:

WARNING: The system only warns of vehicles detected by the radar sensor. In some cases there may be no warning or a delayed warning. Apply the brakes when necessary. Failure to follow this instruction could result in personal injury or death.

WARNING:  The system may not detect stationary or slow moving vehicles below 10 km/h.

The Context: As pointed out in a three-year-old Wired article, radar is the main problem in these systems. It does not have a high enough resolution to tell the difference between, say, a stationary road sign above, or a vehicle on the road below that sign. So above 50mph, radar starts ignoring some of these inputs, which can lead to these crashes. 

But Tesla and others are working to fix that. Tesla's newest vehicles have ditched the radar and now rely entirely on camera input for self driving decisions. Cameras should not have the same limitations that radar currently does. Unfortunately, most other auto manufacturer driver assist systems are radar based.

In the few weeks since the start of the investigation, Tesla has sent a free software update to allow its vehicles to detect flashing first responder lights and slow down for them at night. Over time, the system should improve, allowing the car to change lanes away from the emergency vehicles, just like Tesla vehicles already change lanes on their own to move away from construction cones. 

Photo courtesy of Tesla.