I'm interpreting this paywalled article title literally, so I'm assuming driverless still can't solve the traffic jam?
A solution to this could be far less complex than using AI or sensors (installed per car) to steer the user automatically. Consider curing congestion by connecting most car's existing cruise control to a city-wide traffic light network:
Metal strip sensors are embedded into the first couple dozen feet of road at the beginning of an intersection, and this length is determined by the local DoT according to expected throughput (sometimes there are 3 or more sensors to count how many cars are queued up). This is because over the past several decades, classical traffic control created the enforceable expectation that vehicles come to a complete halt at the color red.
There is generally a pattern constant throughout all cities: primary arteries take priority until the left turn sensor is activated on the street parallel to the oncoming street, but the perpendicular street sensor activation takes priority before this. These are usually lower speed neighborhood or shopping outlet access capillaries emptying out into the higher speed artery stream.
Think about the feeling of seeing a dozen cars and heavy trucks going 40 mph and suddenly having to stop for a yellow light because only one car has activated the perpendicular sensor. That's a lot of wasted kinetic energy for just one car to cross, but timers and sensors guarantee static waiting times for the single car - something that a 2 way stop cannot guarantee.
Noticing that a car has activated the sensor is how I manage to catch most lights green - knowledge of the programmed sequence and line of sight of each of the 8 sensor sections means letting gravity slow me down at just the right time.
When a red light has been modified to interface with the approaching vehicles smart phone GPS and cruise control - "herds" of traveling cars can have their speed set in order to accommodate cars from lower speed capillaries without ever coming to a complete stop.
Here in Reno, a walk up one of the hills surrounding the city at night can lend a birds eye insight into the "herding" concept (large sections of the city can be seen without obstruction, headlights make crowd dynamics clearly visible). Speed limits and fear of enforcement generally means vehicles will cluster up. This pack traveling at their known speed (especially when giving consensual control to what we can call "Herd Cruising") can get through green lights while reducing wait times for perpendicular traffic utilizing the original sensor system. This same traffic could bypass the light similarly if the system already knows about an approaching bulk of participating "Herd Cruising" vehicles, although capillaries would mean cars entering the road and less likely to have time to herd together.
This could increase fuel economy, decrease waiting/idling time, save brake pads, and reduce emissions.