Panos Prevedouros, a professor of engineering at the University of Hawaii
Panos Prevedouros, PHD, professor of Engineering at the University of Hawaii
Panos Prevedouros, PHD, professor of Engineering at the University of Hawaii

BY PANOS PREVEDOUROS PHD – Quite a lot is possible, but how much will it be realized?

Driverless cars hold many promises for improvements in traffic safety and traffic congestion. However, their high price (roughly $30,000 to $75,000 added to a vehicle’s purchase price) virtually guarantees a minimal market share for many years. Let’s use the all-familiar hybrid cars for a comparison.

Hybrid cars come with a modest $2,000 to $7,000 premiums over the traditional versions of the same car, and offer 10% to 100% better fuel consumption. Their market share in new car sales rose from 0.06% in 2000 to 3.01% in 2012. So ten years after their introduction, the share of driverless cars will be 0.1% or less. With one driverless car among one thousand traditional ones, the savings in safety and congestion will be nil.

However, driverless cars may shine as part of brand new cities like Brasilia. Automated buses and 100% driverless cars will provide swift transportation on vastly narrower highways. For example, today a typical 4-lane highway has a capacity of roughly 4,500 cars per hour per direction. With driverless cars on them the capacity of the same exact roadbed would be about 20,000 cars per hour per direction.

Why so? Because driverless cars can follow each other at a spacing of 0.5 seconds (engineers call this spacing the “headway”) instead of the average human headway of 1.5 seconds. This difference from 1.5 to 0.5 seconds of headway triples the capacity of a highway lane from 2,200 vehicles per hour to over 6,000 vehicles per hour. Also selected highways and arterial streets can be converted to driverless car highways with 8 ft. wide instead of the current standard 12 ft. wide lanes because driverless cars can adhere to a tight lane discipline.

In a new, planned city, a 2-lane road with driverless cars can operate congestion-free and crash-free at a capacity similar to a 6-lane road with traditional traffic!

In my opinion, the promise of driverless cars is limited on common roadways, and few may be willing to pay the premium. However the promise of driverless cars is huge on exclusive highways and purpose-built urban areas in fast growing African and Asian countries.

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