Autonomous cars are generating incredible hype, but whether they become a curse or blessing depends on how they are used. Car manufacturers are steering automatic vehicles (AVs) toward a curse for our crowded cities and our climate targets. Making empty cars drive around – to run errands or just to avoid expensive parking – could clog already crowded roads with even more vehicles.
Olli autonomous buses
Local Motors by LM Industries Group Inc.
An autonomous bus rapid transit system, however, could help solve urban traffic woes, the decarbonization challenge, and the fight over expensive space in our cities. This concept combines the already successful bus rapid transit (BRT) model with the efficiency and flexibility of autonomous driving technology. In a world where more than two-thirds of the population is projected to live in cities in 2050, an efficient and low-cost urban traffic system ensuring the lowest possible emission rates becomes crucial.
Autonomous driving miles add up fast
If everyone simply swapped their current vehicles for AVs, urban sprawl and traffic chaos would escalate. In one day the average American driver – let’s call him Tony, takes 2.2 trips – driving for 51 minutes and covering 31.5 miles. How would Tony’s behavior change with a self-driving car? In a hypothetical scenario, Tony works downtown where it is expensive to park. So, his self-driving car just parks farther away and picks him up again later. A Seattle-focused study suggests this could increase vehicle miles traveled (VMT) by an average of six miles, meaning Tony’s estimated VMT would increase 20%
Statistically, middle class U.S. households are likely to own two cars. Thus, in this example, Tony’s wife – let’s call her Anna– would also drive an AV to work. When Tony and Anna are at work, the cars are called by their kids, who don’t want to pay for the bus and who want to make at least one trip each.
A 2016 study suggests demand from people who would otherwise not drive could increase by up to 10% per person (the study focuses more on senior citizens, but since this scenario otherwise ignores induced demand induced demand of people older than 62, it accounts for induced demand from children). So in this example with two kids we estimate a 20% increase.
Tony’s car might also pick up groceries, and because time is not an issue, it could go to several supermarkets to get the best prices instead of just going to one. In the evening, the car could pick up the family’s dinner orders from different restaurants. Assuming AVs are used for trips that wouldn’t otherwise have been taken, the family’s VMT could increase 5%.
Now that Tony and Anna can work in their cars, they are willing to take longer trips, such as traveling to a nicer restaurant for lunch. In the hypothetical example, this may increase each family member’s estimated VMT by another 10%.
The fact that AVs can drive closer together creates space for more cars on the road, reducing traffic and enabling people to reach their destinations faster. Personal vehicles therefore become more attractive, boosting demand up to 10% per person in this example.
Finally, instead of living in an expensive apartment closer to the city, the family might move to a nicer, cheaper house farther away because the family members can use the time while driving and travel faster. The attendant urban sprawl could potentially increase the length of all other trips, such as for taking kids to school or for errands. In total, in this hypothetical example, VMT could increase from 63 to around 156 miles per day for this average family.
Additional vehicle miles traveled with autonomous vehicles
Elisa Miebach
Sharing is key
Sharing AVs can decrease traffic, but a shared AV model shouldn’t rely on self-driving vehicles that pick up one person at a time because optimized driverless systems decrease marginal costs of driving, incentivizing people to take Uber or Lyft instead of public transport.
Only models that rely on carpooling – for example, a model in which Tony and his neighbors travel to work in a shared AV – can decrease VMT. This means the most efficient system would be a Bus Autonomous Rapid Transit (BART) model. As more and more people flock to the cities, metropolises need an efficient urban traffic system with the lowest possible travel times, prices, and emissions.
Why autonomous bus rapid transit is more efficient
An attractive transport system must be fast, convenient, accessible, reliable, efficient, affordable, clean, and safe. BRT systems have already been successfully implemented in Guangzhou, China, and Curitiba, Brazil. These systems reserve at least two lanes in the middle of major roads for buses. The buses don’t experience traffic jams, interrupt the flow of traffic when they stop to pick up passengers, or block other lanes. If designed well, traffic lights will detect an approaching bus and turn green, and passengers show their mobile ticket at the station rather than on the bus.
And when combined with AV technology, this model is even more efficient. Imagine a future where customers book their rides on an app a few minutes before departing. There are no fixed lines, but the computer calculates the maximum number of passengers for the minimum number of stops for a given bus in real-time. Fewer stops means a faster ride.
Making BART work
A pilot program could start with 12-20 passenger buses, using a greater number of small buses instead of a smaller number of large buses to reduce waiting time and increase flexibility. The system could then easily expand once demand patterns become clear. Due to low construction time and costs, the vehicles could run 24/7 without scheduling driver breaks, and due to higher efficiency and reduced labor costs BART would become more affordable than other transit modes. Studies show that BART can be 27% faster and half as expensive as BRT.
To further increase accessibility, BART stations could be equipped with shared bikes and electric scooters, with the app showcasing these “last mile” options for passengers. This feature would further increase efficiency, as buses would not have to serve small and less-demanded roads. Passengers with special needs could order small electric AVs for their last mile, and handicapped access would be guaranteed because all stations would be at ground level.
In case of a mechanical issue, the bus would drive to a repair shop and the system would immediately send a replacement. Any problem and its solution would be directly communicated to passengers in the app. The system would be less accident prone as the buses would have their own lanes and as human driving mistakes such as driver micro-sleep would not occur.
The vehicles and stations would be checked and cleaned every night. This would prevent the broken-window phenomenon, whereby small cleanliness or maintenance issues increase the chances that the larger system will be vandalized and that people will feel unsafe. The bus would have a button for calling an ambulance and an emergency button to stop and open immediately.
BART – decreasing pollution and congestion
A BART future would benefit society by making personal vehicles less attractive. According to a study published by the European Commission, individual car driving costs society 90 cents per mile, taking into account air pollution, climate change, noise, congestion, road deterioration, time cost, accident cost, health, and vehicle operating costs.
BART could transform both urban and suburban centers, gradually allowing parking spaces and car lanes to be converted into bus and bike lanes. Congestion tolls for car use within cities, such as the tolls introduced in London and New York City, could further disincentive personal vehicles, and revenue could be used to improve public transport and urban planning.
This illustration of a typical stretch of El Camino demonstrates how a new Autonomous Rapid Transit system could be integrated into the corridor while maintaining and even improving vehicle, bicycle, and pedestrian flow.
Urban Footprint
Bumps on the road to a successful BART
“The technology of autonomous vehicles is already advanced enough to work on wide lanes in a block system in most American cities,” says Wolfgang Bern, managing director of autonomous bus manufacturer HFM. But despite its promise, BART still faces some bumps in the road. The foremost challenge is public acceptance, which requires resetting public expectations around personal vehicle use and AVs.
BART will also entail job market changes. Employment will need to shift to technological development, repair and maintenance, and system planning. Automakers are slowly realizing they must invest more in public shared transport to stay competitive in the future. Despite the need for big initial investments, this system ultimately could be more cost efficient because many negative externalities of cars would be prevented and money saved could be used to retrain displaced workers.
To decrease pollution and emissions while increasing energy efficiency, the vehicles should be electric, with software to optimize energy usage. But because of high usage needs, the electric buses would have to charge several times a day at current battery standards. Charging could rotate during off-peak hours, and stations could adopt fast-charging infrastructure and inductive charging as the system scales.
The transport system of our future
Of course, BART would not replace current subways. Instead, subways would serve long-distance transport and have fewer stops; BART would serve medium distances and more stops than the subway. Short-distance and last-mile transport could be served by shared bikes and electric scooters. Given these attractive transport modes, people would rely less on passenger vehicles. In all, BART would become a revolutionary tool to decarbonize our transport system.
