How do autonomous vehicles detect emergency vehicles prior to “seeing” them?


As a human, we can hear the siren of an emergency vehicle approaching and take action (pull over, do not proceed into intersection etc) well before the emergency vehicle gets to us. How do autonomous vehicles such as those from Waymo/Cruise do this? Do they only take action when they “see” the blinking lights? Could a tow truck or other maintenance vehicle with orange blinking lights fool a autonomous vehicle into thinking it was an emergency vehicle?

In: 10

Some emergency vehicles have systems that alert traffic signals of their presence, so that could be one way.

Many jurisdictions have sensors on traffic lights that detect traffic priority/traffic preemption signals emitted from the front of emergency vehicles. Basically a specially coded IR light pulse. Autonomous vehicles could have the same sensors installed, forcing them to pull over and stop for emergency vehicles.

They don’t really. They have to see them. At least for now.

As far as being confused, probably not. Emergency vehicles have pretty distinct types of lights from a tow truck, and AI stuff is generally pretty good at this kind of simple A or B type of classification.

But also people don’t just pull over when they hear a siren. They look for where it’s coming from and take action appropriately once they see it. Pulling over onto a shoulder for example might end up blocking the vehicle. People will still go through an intersection, just with more caution, and stop if they do see an emergency vehicle coming. And emergency vehicles slow before intersections to make sure drivers can see them before going through a light.

Autonomous vehicles are looking 360 degrees 100% of the time. They don’t need a reminder to look behind, or pay more attention at an intersection, so they are generally pretty OK , at least in theory compared to human drivers.

Right now though really the issue isn’t so much detection, it’s appropriate response.

There’s stacks of training data available for normal driving. But much less so for unusual situations such as coordinating with other drivers to clear a lane. A person can make a judgement call if they really need to pull off into the grass, and if doing so is gonna run them into a ditch, if they can wait for other drivers to pull out instead, if the need to inch into an intersection to clear room, etc. Autonomous vehicles just don’t have that kind of decision making capacity. Yet.

I don’t think they can do that for now and while it seems like a simple thing when performed by a human, if you give it some thought it actually becomes quite complicated:

1. You hear a siren – Ok! Is the emergency vehicle coming from behind so I should move to the right? Is it on the other side of the road moving in the opposite direction in which case I do nothing? Is it aproaching the same intersection as me or is it on a different trajectory that won’t intersect with mine? Even if you couple it with specific light detection it still is pretty complicated.
2. Emergency vehicles use only lights in some cases (certain zones, at night, etc)
3. Detecting lights only would also be problematic. What would the vehicle do when it encounters an accident scene where the police has already arrived and left the blue lights on to warn other drivers about the incident/obstacle/etc.

I use to work for Waymo before they became Waymo. Waymo vehicles actually listen and pick up the sound of the sirens sometimes before they even see it like we do. For example if a emergency vehicle is coming from the left side but it is unable to see it due to buildings, obstructions, etc, a warning symbol comes up on the system that it has detected emergency sirens, but it needs to see the flashing lights before it takes any action. Back in the day, the software really did not have any good way to deal with the emergency siren and remote people would take over the car to make it a) maneuver through traffic or b) make it pull over. Pretty sure nowadays, it can automatically pull over and probably still have people occasionally having to take over.

Each city/state/area uses a specific pattern for emergency lights. Waymo for example was fed this data for Arizona so no there was no way for a non-emergency vehicle tricking the self driving car to pull over.