Autonomous Vehicles

How Automated Vehicles Reduce Congestion

Autonomous vehicles promise reduced road accidents and an improved rider experience. Autonomy does nothing for congestion, but electronically connecting the vehicles does.

An autonomous vehicle need not be connected; fancy instrumentation and software may replace the human driver. Communicating with others reduces the technical problems. Costs tumble because vehicles do not need the most expensive equipment; sharing data improves each vehicle’s estimated relative position.

Many new cars offer Adaptive Cruise Control (ACC), a feature that tracks the position of the car ahead, and varies vehicle speed as appropriate. ACC without communication produces the same stop and go as manual drive. Supplementing ACC with information about several leading vehicles yields smooth platoon acceleration or deceleration; this technology by itself can double freeway lane capacity.

Data to share include each vehicle’s best estimate of its position, heading and speed, as well as its estimated distances to adjacent vehicles. These data can be uploaded to the cloud, which can look at the overall situation, improve and download the individual estimates.

Better road utilization

All vehicles sold in Europe and North America are required to have on-board diagnostics. The diagnostic system knows everything happening in the vehicle – including state of the accelerator, brakes, and steering wheel. These data can be shared with nearby vehicles.

Manually driven vehicles need to maintain minimum spacing so that the driver can observe and react to unexpected behaviors. Automated vehicles can operate with a much smaller gap, especially if they foresee the intended actions of the car ahead.

Automated vehicles travel in platoons, with distances between vehicles as small as three meters at freeway speed. Highway capacity increases by a factor of three. An external traffic computer can control vehicle behavior.

Road traffic: The end of Stop and Go

When manually driven vehicles are stopped at a red light, starting again is a chain reaction. Each driver needs to verify that the car ahead has started moving, and that there is a reasonable gap. Starting a line of stopped vehicles is a slow process.

By contrast, a stopped automated platoon has no such restriction. Every vehicle can start moving at the same time.

Driver slowing reaction to a hill or a roadside distraction produces a shock wave that slows following vehicles. Automated control smoothens or eliminates such slow-downs. Vehicles within a platoon are tightly spaced, but a large gap to the next platoon defeats shock waves.

Some people expect that we will perfect autonomy, then at a later stage, get the vehicles to cooperate. A better course is to set up cooperation first on dedicated lanes, bypassing the technically difficult problem of designing a vehicle that can deal with any situation.

Security: A top priority for autonomous vehicle technology

Sharing data between vehicles is advantageous, but carries the danger of exposure to hackers. Someone could mess with your Engine Control Unit or change the driving instructions that were meant to keep you in the platoon. If the industry fails to adequately address security, automated vehicle technology could die.

If done right, we can have more road capacity without pouring any more concrete. However, strong security is essential.

What would convince you to trust your car to an external road traffic control computer? Do the promises of reduced congestion merit increased government spending to implement automated transportation? Share your thoughts in the comment section.

Please note that this article expresses the opinions of the author and does not reflect the views of Move Forward.


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