Features
15 Mar 18

How self-drive, car-pooling and road tolls will reinforce each other

Autonomous driving is the main attraction when it comes to future mobility, but according to researchers from Stanford Graduate School of Business, two less futuristic technologies have the potential to be equally disruptive: road-pricing and car-pooling. 

In a recently published paper, they examine how these three technologies could optimally interact to transform transportation.

GPS positioning
Current toll technology has already made road-pricing a lot easier and cheaper than when it involved human toll collectors, and inevitable payment stops. But even today's automated hardware, limited to certain payment points, will be superseded by a more efficient – and thus likely much more widespread – system based on GPS positioning of the vehicles themselves. 

Car-pooling has the potential to greatly reduce congestion, pollution and cost. But the system is not popular: in the U.S., only 9.3% of commuters car-pool, while 76.4% drive solo. Again, technology has the potential to effect drastic change. Apps such as Waze Carpool and Scoop are already able to dynamically locate ideally compatible car-pool partners, to track reputations, preferences and patterns, and to seamlessly process payments.

Reducing friction
According to the researchers, technological progress won't just reduce the 'friction' that is still curtailing the potential of both road-pricing and car-pooling. It will also allow them to interact with each other, and with the rapidly advancing autonomous driving technology, to radically transform mobility.

Or, as the paper states: “The overall progress in information technology makes self-driving cars feasible, and also brings about dramatic improvements in car-pooling and road-pricing. Autonomous transportation technology, in turn, makes carpooling and road pricing even more attractive. Finally, next-generation car-pooling and road-pricing technologies are highly complementary and make each other more attractive”.

Main questions
The paper sets out to establish road-pricing and cost-sharing among car-poolers to optimise the flow of traffic. “To the best of our knowledge, this is the first paper that jointly characterizes efficient tolls and efficient carpooling arrangements”, the researchers state.

The main questions raised: How should road prices be set? What's the best way to organise car-pooling? How much should car-pooling passengers pay? And how should car-pooling interact with road-pricing? Some of the conclusions reached by the paper:

Additional benefit
As long as the number of cars on a road segment is below that segment's capacity, the speed of the traffic flow does not depend on the number of cars – so there is no additional benefit from attempts to reduce that number further, for example by road tolls. This is true especially for highways, less so for intra-city traffic, where the relationship between the number of cars and traffic speed is more gradual.

On highways, the main concern should be to keep traffic below hypercongestion levels. This approach – while only an approximation of full social welfare maximisation – is the right first step for system-wide toll systems.

The assumptions of the paper are based on frictionless matching between car-poolers, but “how such platforms will operate and compete is an open question for future research”.

Read the entire paper here.
 

Authored by: Frank Jacobs