Will Autonomous Vehicles Solve Congestion?

Autonomous Vehicles (AVs) are being touted as the next big idea in solving today’s transportation problems. Every major car manufacturer, and even some consumer electronic companies, are developing AV prototypes and the technology will reach the market in as little as 5 years. In Canada, General Motors has made the large commitment of building an AV research centre in Oshawa, and Blackberry is one of the leaders in AV technology. To many, especially in the auto industry, AVs are the way to go in a society free of congestion. Professor Marianne Hatzopoulou, a professor in the University of Toronto Transportation Research Institute (UTTRI), discusses some of the potential benefits of AVs, saying “AVs have the capability of platooning, they have faster acceleration and deceleration reaction times, which means that they will probably use less road space. This will contribute to reducing congestion.” However, the question remains whether AVs will actually solve congestion and improve our quality of life or if they’re a ploy by car manufacturers to win back market share that’s been lost to transit and active transportation since the early 2000s.

First off, there is no question that AVs will drive more efficiently than regular drivers. They are able to drive closer to other vehicles and can adjust their speed to manage flow and reduce stop and go traffic. AVs can also communicate with other AVs to create an effect called platooning, allowing AVs to communicate with each other to manage space and create a smooth flow on the road. However, being better than the least dense mode of transportation will not solve congestion. A standard 40 foot transit bus that has more than 4 riders is able to fit those riders far more efficiently than three 15 foot long Toyota Corolla’s (one of the smallest cars on the market) lined up bumper to bumper, assuming an average car load. Even with all the seats filled in a Corolla, a bus will only need 15 people on board to be more efficient, which many TTC bus/streetcar routes easily accomplish. Buses and especially streetcars and trains are more space efficient on precious downtown road space than any series of AVs, small or large, simply due to the fact that multiple AVs will create wasted road space through multiple engines, empty seats, trunks, bumpers, etc. Trains are even more efficient in fitting riders onto the same footprint and do not use road space to transport their riders. Bikes and pedestrians are also more efficient in packing people onto sidewalk and road space, and have the additional benefits of promoting a healthier lifestyle and increasing business activity where they travel. So, while AVs do move people better than regular cars, geometrically they fail to move more people in the same amount of road space than bikes, pedestrians, buses, streetcars or trains, which is important since new road space is rarely added in established areas of the city.

Whatever road space AVs do create over regular cars may be eaten up through induced congestion. Induced congestion is an observed phenomenon where after new roads are built, or existing roads are widened, the new road space will be immediately filled through people switching transportation modes or taking longer trips. Hatzopoulou also touched upon the effect of mode switching and the possibility of a rebound in congestion. “…More space on the road can lead to a re-bound effect. This means that individuals who were taking transit because their travel time to work was too long (specifically due to congestion), may now find it attractive to take their car (AV or conventional). We end up with the same number of cars on the road if not more.” Any space that AVs do create will get filled because other people will switch to AVs because it will become easier to drive. In the end, congestion will remain the same. AVs can also increase congestion since it makes driving easier and attract people to switch modes from transit, cycling, or walking. Those modes of transportations are more efficient at moving people around, and those switching will increase the strain on the road system and increase congestion.

What if cities adapted their planning policies to be friendlier to AVs and increased available road space? Ignoring the issues posed by induced congestion, this means lower population densities, and increased sprawl to accommodate the increased road space available to AVs. Congestion may decrease, but sprawl causes more significant issues. Increased travel distance with sprawl will increase Vehicle Kilometers Traveled (VKTs) and dramatically increase greenhouse gases emitted by vehicles. Cities will either have to waste land that can be used for anything else on parking, or let AVs run around the cities like taxis which increases VKTs and greenhouse gases. The lower population density means more land will be used, land that can be used for farming, or protecting what little natural environment the earth has. Cities will also have to deliver services such as fire services, water, and schools, over a larger area, creating an increased financial burden on taxpayers. Most importantly, this type of car-centric development has already been tried and belongs in the 1950s. It does not work, and cities have been moving away from development that prioritizes VKTs since the early 2000s. Such an approach to AVs would reverse any progress cities have made and cause all those problems to resurface again.

There is one thing that AVs will do to benefit society. There is no question that, with the amount of sensors and more even-handed decision making that AVs have, roads will be safer for other motorists, cyclists and even pedestrians. Today, many autonomous technologies are being implemented in cars like lane detection warnings and object detection. While they may make the current human driver more complacent and encourage unsafe behavior in the present, it will be computers who will make those decisions in the future, either locally or by communicating with other cars. AVs will also make it easier for people who can afford cars but cannot drive because of a variety of mobility issues to get around a city. While this may not matter much in cities, in suburbs or small towns, this will create a lot of opportunities just by giving more people the freedom to travel around without relying on others.

That being said, there is a lot of concern about how quickly AVs are being implemented by car manufacturers without adequate planning from cities. AVs will not eliminate the need for transit or active transportation, not just because of the lack of infrastructure, or the increase in sprawl, but because there are segments of the population who are not able to financially support a regular car, let alone an AV. The ultimate effect of AVs is unclear and while this article may be negative on the prospect of AVs, the reality is there may be tremendous upside in the arrival of automation in transportation; though the true effect of automation remains to be seen. Researchers such as Professor Hatzopoulou are taking steps to find the ultimate effects of AVs. UTTRI has founded the iCity Centre for Automated and Transformative Transportation Systems (iCity CATTS) to look at the effects of automation, ridesharing, and other transformative technology will have on transportation. “The centre groups researchers from various disciplines interested in studying the effects of AVs on the city. Some researchers are interested in the effects on traffic, others like myself are interested in their effects on GHG emissions and air quality.” states Hatzopoulou. “The purpose of iCity CATTS is to enhance collaboration between the various researchers and foster dialogue with planners and decision-makers who are in dire need for answers on the impact of AVs on the cities of tomorrow. How can we use this technology to promote more sustainable, more equitable, and more efficient cities? [These are] the question that motivates CATTS.” Ultimately, cities should not believe the hype of AVs and not treat automation as the one size fits all solution to solving congestion. Rather, cities should consider the other transportation solutions and modes that can be part of a multi-modal approach to target every cause of congestion.

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