Building roadside sensors along our streets and motorways so cars can navigate them sounds like an expensive dream. But, a series of advances are coinciding to make such a system possible. Fifth Generation wireless, or “5G,” is a wireless broadband standard that’s currently under development and will improve on our current networks in ways that will be useful for driverless vehicles. A 5G system will include denser wireless networks speeding up connections and will also have broadcast capabilities, allowing networks to distribute large amounts of mapping data without time lags.
Sensor technology is also getting better and cheaper; to sense and react to the world, driverless cars use a series of technologies, including radar and cameras.. Lidar systems emit invisible laser light that reflects off of objects in view; then, the lidar system times the speed of the reflection to measure distance, creating a precise, three-dimensional image of the world. The best systems don’t come cheaply. The distinctive spinning lidar unit that you see on top of Google’s automated Lexus SUVs cost about $75,000 per vehicle.
Mounting these sensors to cars comes with drawbacks, especially for vehicles that are only partially autonomous. Car-mounted lidar sensors have a range of 200 meters, and perform best under 100 meters. That means that if a car is travelling between 30 and 60 mph, a passenger will have around 5 to 15 seconds of warning of an unusual situation up ahead.
These takeover requests can be jarring, irritating, and dangerous. Researchers at Virginia Tech found that passengers took an average of 17 seconds to begin driving in such situations. Passengers on road trips, who might be sleeping, eating, or watching a movie would need even more warning. Roadside sensors, however, would allow vehicles to “see” activity far ahead on their routes. With roadside sensors, passengers might have minutes, instead of seconds, of warning. Smart roads could also provide more descriptive information to vehicles, letting them know, for example, that the person-shaped object near a sensor is a Halloween scarecrow, not a child.
There are other benefits. Car-mounted sensors are often confused by road materials (a shift from dirt to gravel), reflective buildings, bridges, or even the weather. Roadside sensors not only mitigate these problems, but also reduce the computing load on car-mounted systems, because the vehicles have to make fewer snap decisions.