Self-Driving Cars Struggle To Cope With Lane Splitting Tactics Of Motorcycles

Dr. Lance Eliot, AI Insider

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I recently posted a column about the latest aspects of motorcycles and how AI is making them semi-autonomous and fully autonomous, see:

I thought it might be handy to consider another aspect about motorcycles, namely the somewhat controversial practice of motorcyclists that practice doing lane splitting.

Have you ever heard of lane splitting?

How about lane sharing, or lane white-lining, or even sometimes referred to as strip-riding?

Here in California we are quite familiar with this terminology since it refers to something we see every day, namely, motorcyclists that go between the lanes on our highways, freeways, and byways.

This is one of those aspects about California that one might be conflicted about.

We are the only state that specifically has made it a legal practice to do lane splitting.

Some states outlaw it outright, while most states are silent on the matter and tend to either allow it implicitly or kind of look the other way about it.

Controversy Surrounding Lane Splitting Practices

No matter where you are, I’d bet that there are rather divided opinions about the practice.

The notion is that motorcyclists do not necessarily need to make the same kinds of lane changes that cars need to do.

A motorcyclist is allowed under “lane splitting” to go between two cars and squeeze along forward.

Imagine that a motorcyclist is doing 65 miles per hour and comes up from behind you and another car that is next to you on the freeway.

The motorcyclist is blocked seemingly because you and the other car are occupying the two lanes. Other cars behind you would need to wait until somehow an opening develops, such as if you speed-up or the other car does, and the two of you are no longer going neck-and-neck.

In spite of the apparent momentary blockade by you and the other car, if a motorcyclist believes they can fit between you two, they are legally allowed to do so.

You might be tempted to say that this practice seems reasonable.

Why not let the motorcyclists be able to do lane splitting if it makes their commute more efficient?

Well, sadly, it has become commonplace for me to see a motorcyclist take a spill onto the freeway as a result of a lane splitting maneuver.

Thus, this takes us to the core of the controversy about the lane splitting approach.

Some would say it is an overly dangerous practice and should be banned.

By and large, a lane splitting incident is going to involve a car. Therefore, car drivers are just as involved as the motorcyclists.

Motorcyclists here will tell you that much of the time it is the “foolish” car drivers that are at fault.

A motorcyclist trying to squeeze between two cars will often inadvertently get bashed by one of the two cars. A car driver might have swerved to the edge of their lane, doing so presumably without awareness of the presence of the motorcyclist.

There’s another factor to these incidents that you need to consider.

When a motorcyclist has an incident during lane splitting, it often inadvertently entangles other cars and car drivers into the incident.

Guidelines About Lane Splitting

Last year, the California Highway Patrol (CHP) announced new guidelines about lane splitting in California (note that due to a legal controversy arising from the initial posting of the guidelines, the CHP subsequently took them down and a further review process is underway).

Let’s consider the initial draft guidelines that were posted.

First, the CHP recommended that only experienced motorcyclists try to do lane splitting.

This is certainly sage advice.

In reality, I’d suggest that most motorcyclists here on our freeways do lane splitting, regardless of their experience at riding a motorcycle.

The CHP recommended that motorcyclists only do lane splitting when traveling at no more than 10 miles per hour faster on the motorcycle than the prevailing car traffic around them.

Furthermore, the CHP recommended that lane splitting be only undertaken when the prevailing traffic is going below 30 miles per hour. More sage advice.

This seems to be rarely followed by the motorcyclists that I see on our freeways.

The CHP recommended that lane splitting only occur between lanes #1 and #2.

This would be considered the fast lane and the lane to the right of the fast lane.

Though this is again quite sage advice, I’d say that lane splitting seems to happen on any lane at any time.

One recommendation stated that a motorcyclist should not lane split near large vehicles such as buses and trucks.

The CHP recommended that motorcyclists doing lane splitting should be wearing brightly colored clothing and gear.

I’d say that most of the motorcyclists that I see are usually wearing traditional oriented motorcyclist clothing consisting of black or brown leather jackets, and rarely do they have any kind of especially high-visible clothing or gear on them. Until or if the motorcyclist culture somehow changes toward brightly colored attire, I’d say that this CHP recommendation is unlikely to be widely adopted.

There are even recommendations for car drivers.

The CHP indicated that car drivers should not try to impede a lane splitting activity.

Indeed, some car drivers try to block the act of lane splitting, which can be a quite dangerous cat-and-mouse game.

The final piece of CHP sage advice that I’ll mention herein is the aspect that per the CHP recommended practices that car drivers are to try and aid or enable lane splitting by shifting in their respective lane at the time of the lane splitting action.

This to me seems the most questionable suggestion of the various points made.

It is one thing to tell car drivers to not impede lane splitting, it’s another idea altogether to have car drivers try to make it easier to do.

AI Autonomous Cars And Lane Splitting Handling

What does this have to do with AI self-driving driverless autonomous cars?

At the Cybernetic AI Self-Driving Car Institute, we are developing AI software for self-driving cars. In our view, this also includes the ability of self-driving cars and the AI to be able to contend with lane splitting.

For many of the automakers and tech firms that are making AI self-driving cars, the notion of dealing with lane splitting is quite low on their priority list. Indeed, they would tend to say it is an “edge” problem.

When I’ve had discussions with them about this matter, they tend to point out that only California has a law that legally allows lane splitting.

Why worry about a law that is only pertinent to one state?

They are trying to make AI self-driving cars that work for anywhere in the United States and so it is “obviously” a rather limited concern when it is only lawful in California.

I refute this idea that it is only limited to California. As mentioned earlier, many states allow it by not explicitly banning it. Plus, I assert that motorcyclists all across the country at times will do lane splitting, even in places where it is banned (I’d bet that most motorcyclists think it is a pretty low chance they would get nabbed for doing an illegal lane split, unless they did so brazenly and stupidly in front of a police car).

Lane splitting is actually quite popular in parts of Europe and in many Asian countries.

If you are making an AI self-driving car, I’d suggest you ought to be considering how the self-driving car and the AI will cope in countries besides just the United States.

So, I tend to reject the idea that dealing with lane splitting is a rather narrow topic of only concern to California driving.

There are some that suggest that even if lane splitting is worthy of consideration, you can delay worrying about it by instead just letting lane splitting happen for the time being.

In other words, if a motorcyclist wants to lane split, let them go for it. The AI of the self-driving car presumably could care less that the motorcyclist is doing the lane splitting. No need to contend with the matter. Just let it happen. It’s all on the shoulders of the motorcyclist.

If your view of a self-driving car is that it is sufficient for it to drive like a novice driver, I suppose there is some merit to this point about ignoring the lane splitting.

I cringe at this belief.

Autonomous Cars Dealing With Lane Splitting

In short, I reject the idea that lane splitting can be “ignored” and also that even if being considered that it should somehow be placed at the back of the bus, as it were.

Here’s a few reasons why being aware of lane splitting is an essential car driving skill for AI autonomous driving systems.

First, be aware that many of the AI self-driving cars are initially going to be very rudimentary in their driving practices. They will tend to be skittish drivers.

This endangers the lane splitting motorcyclists.

This also endangers other nearby cars, including both the AI driven self-driving cars and any nearby human driven cars.

Machine Learning and Lane Splitting Aspects

How does skittishness play a role?

Suppose a skittish AI self-driving car suddenly has a lane splitting motorcycle that darts within inches of the self-driving car. What will the self-driving car do?

The AI might detect the motorcycle and assume that the motorcycle is on a path to hit the self-driving car. Perhaps the AI directs the self-driving car to make a rapid lane change to avoid the motorcycle. Or, takes some other action that is not quite expected or anticipated by other drivers and nor the lane splitting motorcyclist. This could spell trouble for the AI self-driving car, and the nearby traffic, and for the motorcyclist.

From a Machine Learning (ML) perspective, suppose the AI encounters this lane splitting a multitude of times, but has no context for why it is occurring.

What should the ML learn from it?

If each time it happens the ML opts to take a sudden evasive maneuver, it could be that the ML gradually accepts that this is the right way to deal with the matter. What the ML has “learned” is not necessarily the proper kind of driving action to take.

Overall, I’m suggesting that if AI self-driving cars are skittish or novice style drivers and cannot explicitly deal with lane splitting, they might get themselves into trouble, including possibly making rash driving moves that could lead to harm for any human occupants in the self-driving car, along with harm to other humans in nearby cars and for the motorcyclist too.

Furthermore, for those that suggest that AI self-driving cars will just learn how to deal with lane splitting, doing so after some number of driving hours and experiencing lane splitting, I’m not convinced that what the AI learns will really be the most prudent driving practices related to lane splitting.

If we also embrace the recommendation of the CHP that car drivers should aid the lane splitting action, it seems especially unlikely that the AI is going to figure that out on its own. More likely is that the AI would figure out how to defend against it, rather than to try and enable it.

In general, I’d vote that the AI be explicitly programmed or trained in dealing with lane splitting.

This also must include the realities of how motorcyclists really do lane splitting.

Let’s pile on about the circumstances of lane splitting.

It could happen during daylight when visibility is perfectly clear. Or, it can happen at night when it is dark and hard to see the motorcyclist. It can happen during dry weather when the roads are readily driven on, or it can happen in the pouring rain and the roads are slick and slippery.

There could be just one motorcyclist trying to do a lane split, or there could be a multitude of motorcyclists doing so, all at once (I’ve seen this happen many times during my daily commute, namely motorcyclists riding together as a pack or team).


Lane splitting — is it a boon to our driving world, or is it a contemptible practice that should be curtailed?

I’m sure the debate will be going on for a long time about the merits of lane splitting.

Meanwhile, it exists, and it happens. AI self-driving cars need to be ready for it. None of us want AI self-driving cars that by intent or by happenstance ram into a motorcyclist doing lane splitting or get involved in the aftermath of a lane split that has occurred to some other driver.

Let’s make sure that the AI is savvy about lane splitting.

I’m not willing to split hairs on that.

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Copyright © 2019 Dr. Lance B. Eliot

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Dr. Lance B. Eliot is a renowned global expert on AI, Stanford Fellow at Stanford University, was a professor at USC, headed an AI Lab, top exec at a major VC.

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