Michael Morscher

December 8, 2017

HOV Lanes. EV Lanes. AV Lanes?

Human drivers sharing the roads with autonomous vehicles is assuredly problematic. And, since the government can't even get potholes repaired, it's looking like we won't be able to construct an entire parallel network of roads exclusively for self-driving cars in the foreseeable future. There's going to have to be a compromise in the coming years which takes advantage of existing infrastructure and allowing new technology to exist with the old. About 100 years ago, drivers of the Ford Model T had to battle with horse-drawn carriages until eventually the transportation advancement became ubiquitous. This problem is not unlike that faced today, which leads to the question: If we already have dedicated lanes for HOVs (high-occupancy vehicles) and EVs (electric vehicles), why not dedicate AV lanes?

‍Are dedicated highway lanes for autonomous vehicles a natural extension of HOV and EV lanes? Many industry leaders say 'yes'.

One recent proposal asks for just this. Autonomous vehicles would be allowed in existing HOV and EV lanes by default, with a gradual phasing out of existing traffic from these lanes—and soon from the entire highway. This plan would implement an immediate solution for the small amount of AV traffic out there right now and dynamically adapt to decreasing levels of human traffic.

"By 2025, that HOV lane would be closed to human drivers, along with the one next to it (the highway is eight lanes wide)... those two lanes could be used as three, as autonomous vehicles can safely drive more closely together. By 2030, the majority of the highway would be closed to human drivers, with the takeover complete by 2040." - Wired

Another proposal to designate AV lanes known as Hyperlane would integrate sensor systems with a central computer to monitor traffic volume and optimize travel speeds. There is broad industry recognition of the idea that "smart roads" which communicate with cars, and allow cars to communicate with each other, are essential to optimize speed and safety. But there is a multi-trillion dollar price tag. Deploying this only to select lanes would be a great short-term solution to provide necessary technology while controlling its cost.

‍"Hyperlane" is a proposed network of highway sensors that would allow self-driving cars to synchronize and reach speeds in excess of 100 miles per hour.

Existing highway lanes are rarely in ideal condition, which poses a major problem for current low-level AVs that are dependent on lane sensing. Self-driving cars are programmed to stop or return control to a human driver if input is insufficient, which is what happened during a Volvo demonstration at the Los Angeles Auto Show.  Their North American CEO exclaimed,

It can't find the lane markings!... You need to paint the bloody roads here!”. - Lex Kerssemakers, and probably echoed by all other drivers in America

In fact, about two thirds of American roads are in poor condition, and auto makers have explored self-sufficient technologies but in the end infrastructure must be made compatible. Again, having dedicated lanes in this scenario would allow for focused investments in lanes where cars can't operate without clarity.

‍"Smart roads" would communicate with autonomous vehicles to increase efficiency of traffic flow and ensure safety.

There is always the opportunity for traditional drivers to feel neglected if AVs are prioritized or receive dedicated funding, but AV lanes would strike a good balance in this tradeoff. If existing restricted lanes are used, traditional drivers won't have fewer lanes than they do now (for the time being) and people converting to self-driving cars would reduce overall traffic. Targeted investments in infrastructure or technology might however burden taxpayers who wouldn't benefit from the advancements, which is definitely a concern to consider, but differential tolling on these lanes could offset or eliminate this inequality. If the downsides of AV lanes can be overcome, the potential benefits are unbounded and would provide a clear road map for full AV adoption.

Can this same principle be applied in the urban setting with grade-separated roadways? Or are the special considerations of cities such as shared traffic just too difficult to overcome? These questions and more will be the focus of my next blog post.

Bonus Reading:

Amazon thinks it can handle the rarely considered scenario of reversible highway lanes: https://www.recode.net/2017/1/17/14294498/amazon-self-driving-roads-patent

https://www.wired.com/story/self-driving-cars-take-over-highways/ http://www.bbc.com/news/av/technology-40382959/hyperlane-a-special-lane-for-self-driving-vehicles https://venturebeat.com/2017/05/17/ready-to-pay-trillions-for-self-driving-car-roads/ https://www.salon.com/2017/04/20/self-driving-cars-vs-crummy-american-roads-will-infrastructure-speed-bumps-slow-down-the-future-of-transportation/ https://www.dailydot.com/debug/autonomous-vehicle-america-road-infrastructure/
Michael Morscher
2019
Engineering Psychology and Computer Science
https://sites.tufts.edu/cars/