more on: mobility, land use

An Urban Transit Solution?

+ Alain Bertaud, Brandon Fuller, Jonathan Stewart

In a previous post, we discussed the failure of traditional urban transit systems to effectively move people within the world’s megacities. We then discussed how urban residents are responding to this failure by using individual modes of transport and the possibilities and limitations of combining individual transport with mass transit. A new technology, the driverless car, could present a possible solution to the urban transit problem.

The current trajectory of self-driving cars’ technology means that some of these cars will likely soon be seen on the road operating under normal conditions. Their numbers could become large enough to result in an improvement in urban mobility and by extension in making cities more productive and more energy efficient.

Driverless vehicles present the possibility of door-to-door trips at any time of day for any itinerary, free of the supply constraints imposed by transit networks. Additionally, driverless cars can be used in conjunction with rail access while avoiding the congestion and need for parking space described previously. Rail systems could then be redesigned to make stations farther apart, allowing trains to travel faster over long distances.

More flexible transport will improve access to urban areas that are currently poorly served by mass transit. The improved mobility implied by driverless vehicles will increase the accessibility of firms in cheaper locations. This will increase the size of the labor market for residents and allow firms that would not be viable in a high-rent environment, including startups, to survive and thrive.

Shared autonomous fleets could operate from origin to destination and to and from transit hubs without the problem of empty lots at origin and full lots at destination caused by common commuting directions. Vehicle sizes could be adjusted based on the length and nature of trip (commuting, shopping, leisure) to save on use of road space, road maintenance, and energy consumption. Driverless vehicles improve the potential for car sharing via pre-selection of passengers based on itinerary and trip time, increasing the possibility of linked multipurpose trips, such as stopping by the grocery on the way home.

Driverless vehicles can reduce cars’ consumption of urban real estate by reducing the need for parking and the use of road space while driving at higher speeds—no need for the three-second human reaction time between vehicles (though current driverless cars, including Google’s, maintain the regulated three-second rule). However, it is also possible that the self-driving vehicles used in shared fleets could use more road space, as vehicles will cruise empty to pick-up new passengers.

Additionally, driverless vehicles can reduce the direct costs of accidents (loss of life, injuries, and material costs), as well as the traffic congestion stemming from accidents and rubbernecking. They can also mitigate the unpredictability of travel time due to the possibility of accidents. By lowering the probability of accidents, driverless cars would enable the use of lighter vehicles that require less energy. Driverless vehicles can also reduce energy consumption by moving closer together in pods to reduce drag.

Driverless cars are not a silver bullet for the problem of urban mobility. However, driverless cars used in conjunction with rail systems present the possibility of a big step toward the optimal transportation of urban citizens. This would give urban residents ready access to a larger portion of the urban area and therefore a larger job market.

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