Autonomous vehicles are coming – it’s a matter of when, not if. I believe they’ll be ubiquitous within twenty years and humans driving will be illegal on public streets in 30 to 40 years. Streets take up about 25% of real estate in most cities and autonomous vehicles will likely change the landscape of the city as much as the shift to automobiles did a century ago. This post focuses on how autonomous vehicles will affect cities.
Here are the top 15 ways I think autonomous vehicles will/should change cities:
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- Roads, driveways, parking stalls, and drive aisles should be narrower as autonomous vehicles will handle tighter spaces better than human drivers. It is also likely that vehicles themselves will get smaller (Smart Car and Mini Cooper size).
- Reduce speed limits within cities to 20 or 25 mph. The risk of fatal crashes with pedestrians goes up exponentially with speed.
- More thought will need to be given to designing pedestrian and bicycle facilities. It is likely autonomous vehicles will be programmed to stop for pedestrians in all cases. I think back to my days as a college student and the tremendous amount of jaywalking most students do (disobeying traffic laws and walking wherever was convenient). If college students knew that the car always had to stop for them, I could see significant gridlock as pedestrians took over the roads. A possible design solution is more medians with fences/landscaping that physically impede jaywalking.
- Roundabouts and traffic circles will be more effective than signals and all-way stops as they are easier for autonomous vehicles to navigate. This is good news as there’s a lot of wasted time at signals and all way stop signs (I get frustrated every time I pull up to a red left turn arrow later at night and have to wait thirty seconds for the cycle to change).
- Traffic signs could be eliminated. The cars will know where they are going and the rules of the road could be programmed into the map/operating systems. Everyone will eventually have a smart phone, maybe even imbedded in our bodies with a direct connection to our brain (cyborg here we come). We can debate whether or not we need signs at all, but it is likely the number of signs could be reduced significantly.
- Traffic signals could be eliminated. If vehicles are communicating with each other, priority rules could be developed that allow a giant ballet dance at intersections without the need for traffic signals. I think will be straightforward from the vehicle side, but complicated from the pedestrian/bicycle side.
- Buildings can be closer to the road. No need for huge setbacks.
- Excess public right-of-way can be turned back for infill development.
- Right-of-way standards should get narrower. It is possible the future fleet of vehicles is cut by at least half. Many streets could be reduced to one 8 foot lane each direction with a 10 foot sidewalk or trail on each side. This can be easily achieved in a 50 foot right-of-way. A transition could be an easement in lieu of permanent right-of-way.
- Lower parking needed. Whether you use a robo taxi (think autonomous Uber) or your personal car drops you off at work and goes back home to park/charge, we won’t need as many parking stalls. Minimum parking requirements should be reduced and repurposing of underutilized existing parking should be incentivized.
- Not as much attention to access spacing. The safety benefits of access spacing are due to counteracting human error.
- Travel Demand Management Plans should be more important than traffic studies.
- Robo taxis will want places to park between fares. City’s will need to give more thought to managing on-street parking. A robo taxi would always follow the parking restrictions, but if the tire only needs to move six inches to reset the time limit in a one hour parking zone, the robo taxi could occupy a spot for hours at a time. It also makes me think of my time as the city traffic engineer in an affluent suburb. Residents would be upset if robo taxis decided to legally use a neighborhood as their parking lot. A savvy city will figure out how to lease on-street parking to robo taxis instead of just reacting to what they do.
- Will robo-taxis shift transit the way buses killed fixed street cars? Transit Oriented Design around fixed transit may go away. Aside – robo taxis could be much more equitable than fixed line LRT.
- Consider changing to a vehicle mile tax at all levels of government. It is well documented that “tolling” is the most effective way for government to fund transportation and affect driver behavior through variable congestion pricing. Unfortunately, it is a politically difficult topic as most motorists think of roads as being “free” infrastructure. As we possibly shift from individual automobile ownership to fleet ownership, it may be politically easier to implement a vehicle mile tax. Of course, the fleet owners would have more incentive to hire lobbyists to fight it.
These are my initial thoughts on the opportunity autonomous vehicles presents to cities. Here are more resources for you to dig into if you work for/with government on traffic related issues:
How do you think cities should change with the oncoming change from human driven to autonomous vehicles?
Mike Spack, PE, PTOE
Mike is the president of Spack Consulting. Since 1996, Mike has led over 1,000 traffic engineering projects in Minnesota and Wisconsin. Since 2007, Mike has also been the creative force and principal writer of the industry leading blog MikeOnTraffic.
