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When autonomous traffic takes over

Updated: Mar 13, 2021

It's thirty years in the future. You're at the local minibus station, fifty miles from your destination in Downtown. You choose to step on board. The minibus is climate-controlled, powered by electricity, and accelerates comfortably. Small enough to fit in the digital car slots used by autonomous vehicles, your minibus is guided by a wireless system of computers. In minutes, you are on a freeway used exclusively by autonomous vehicles, moving through a new kind of city.



Step aboard!


Freeway comfort


As you approach Downtown, the freeway merges more autonomous minibuses into the surrounding vehicles like a platoon of traffic, less than a second separating one vehicle to the next. In all, there are more than two thousand autonomous minibus routes that lead directly to Downtown alone. All enter and exit using a freeway. Your minibus promises to deliver you to only one downtown station. It's a forty-five-minute ride, precisely, even though the station was fifty miles away.




Downtown Atlanta with 48 autonomous minibus stations



Autonomous traffic


You can barely see Downtown. Hundreds of skyscrapers peak over green slopes and rooftops. As your minibus comes underneath Downtown's towers, vehicles organize to the outside of the freeway and flow out on ramps. Other ramps place new freeway traffic onto the center of the freeway, rather than the outside. Your minibus is now in the outside lane. You fly up the next ramp, above the freeway, and swing left over the freeway above tightly packed, quick-flowing traffic.



Autonomous traffic will make downtowns bigger



The new subways


Downtown is physically several times larger than it was thirty years ago. Your minibus is destined for one station. It will stop nowhere else. Some major streets have been trenched and capped just as subways lines once were. It’s now financially feasible and physically necessary to separate the high volume of minibuses and other freeway-oriented traffic from the humans above, where many of Downtown’s former streets are now a walkable maze of linear parks. Much of the traffic moves below, unseen.




Pedestrians first - like Atlanta's Beltline, but in Downtown



A Downtown station


A tunnel awaits your minibus above the other side of the freeway. Your minibus quickly merges with traffic from an opposite ramp to make four active lanes, one-way, plus a safety lane on each side, as you dive underground. Soon vehicles are breaking from the flow and slowing to exit. There's a tunnel ramp. A second. Then your platoon narrows to a third.


Like a submarine breeching the surface, your minibus arrives in Downtown. If you weren’t so used to it, the quick pace of minibuses would take your breath away. Every route delivers minibuses every five minutes. The station hosts dozens of waiting minibuses, receiving a new one every several seconds. There are 48 downtown stations currently. The number has grown since autonomous vehicles were granted monopoly of the freeways a decade ago. Each station serves a section of Downtown that's a five minute walk in each direction, approximately a quarter square mile in size. Combined, these 48 stations serve a unified central business district that has grown to 12 square miles, a district that's 75 times the size of California’s Disneyland, or 6 times the size of Midtown Manhattan.




Downtown Atlanta with autonomous traffic



Downtown streets



Recently, this was impossible. The linear parks previously were not justified financially or against the needs of traffic flow, but now they are needed to physically cover high traffic volume or to replace old streets with no new use. The needs of traffic flow, which had always put the pedestrian experience in the backseat has been flipped by autonomous vehicles. Pedestrians now dominate the surface level of Downtown. The density of office buildings reminds you of the 30-year-old movies based in Downtown Chicago or San Francisco's Financial District. Like you, most of the people in the crowded pedestrian greenways commuted from far away, some even a hundred miles away.



Concept by Sidewalk Labs at Google


Train routes reborn


Some of Downtown's most glorified greenways were formerly railroads. Most were commercial routes used for logistics before they were replaced by autonomous trucks, but some of the railroads were for rail-based mass-transit. In New York, they were called "subways." Now they form the basis of pedestrian routes which are most popular with cyclists and scooterists for their isolated rights-of-way. Some subway trenches have had their ceilings pulled back to a reveal the city from below, wires, pipes, guts, and sky.




A price was paid.



The price


For this new kind of city to have come into existence, cherished neighborhoods were bulldozed for downtown expansion. Once-suburban neighborhoods now a short trip from Downtown, have gentrified like their inner-city counterparts. Greater density was needed. Some homes and strip malls were torn down and replaced with mixed-use apartments and townhome communities. Further away, farms and forests have given way to new suburbs.




Dense areas within 30 minutes of Downtown Atlanta with autonomous traffic


Thirty years earlier


Thirty years earlier, expensive work was performed to expand rail-based mass transit. Old homes in areas destined to be razed were wastefully refurbished. Freeway caps and towers were built wrong for the new nature of freeways. New mega-developments were problematically designed for human-driven cars rather than autonomous ones. New suburban neighborhoods were built in the wrong places. Light-rail systems lived short lives. Developers targeted the wrong places for infill housing. Bridges were built that would quickly need to be town down and replaced.




Look at me. I am your captain now



Then and now


In rapt fascination, students, academics and journalists will talk about how we tried to reinvent our cities for comfort and density as though human-driven vehicles would keep being useful, even dominant. How long we collectively remained in the dark and resorted to achieve some of the smallest, shortest-lasting successes. But they will also learn of the experts and leaders who were the earliest to identify how autonomous traffic systems would reshape our cities so that traffic was no longer managed, but controlled.



Berlin - downtown stations (blue) with new autonomous freeways (black)

The blueprint


Congestion will be replaced with traffic pricing algorithms that we can write and understand now. Autonomous stations, tunnels, and freeways can already be duly planned and designed. A standard for the distance in between autonomous vehicles already exists, as do standards for comfortable acceleration and lane width. We already know which fixed merging patterns are best. And the benefits of congestion pricing. And the benefits of symmetrical design.



Paris - new areas (orange) within an hour of downtown with autonomous traffic

The jump


For one example of how autonomous traffic can be designed, see the Atlanta Model.



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