the VZ solution we won’t talk about

The one thing that no one in the transportation advocacy community wants to talk about is speed-limiting vehicles. Speed-limiting means that vehicles cannot operate over the speed limit selected for a section of roadway. The technology for doing this is largely already in place on modern motor vehicles, as they already monitor their speed and already have available information about the speed limit on the street they are on. Older vehicles of course don’t, and would need to be retrofitted.

Why speed limiting? Because it is a simple solution that cuts through all the other discussion and contortions and expense of other solutions. Some people think education is the solution, as though all the education to date has done any good. Some people don’t want any traffic laws enforced, because ‘freedom’, meaning of course the freedom to operate a vehicle recklessly and kill people. Some people think that the solution is to redesign roads so as to prevent speeding. I’m not against that solution, but our mis-designed transportation system has a value of trillions of dollars, and fixing it will require trillions of dollars. We could spend our money that way, but why when we have so many other good causes to spend on. Vision Zero efforts are admirable, at least when they don’t have the involvement of law enforcement, but there has been very slow progress or regression in the United States because the engineering profession and law enforcement really don’t believe in the idea, giving it lip service while trying to subvert it.

Speed kills. It increase the severity of crashes, making severe injury and fatality more likely. It also increase the frequency of crashes, because drivers have less time to react and avoid, or slow before impact. You have all seen a version of the graph below, and it is important to remember that at every speed, speed is a contributing factor.

Speed limited does not mean changing posting speed limits, though it turns out that reducing speed limits does indeed reduce traffic speeds and reduce crashes and injury severity. However, speed limits are not set to the design speed of the road, but lower than than. As a result, drivers are encouraged by road design to speed, while fingers are wagged and tickets are written. But the problem is not solved. Crashes and severe injuries and death continue apace, or increase in the case of this last year.

With speed-limiting, no vehicle goes faster than the speed limit. If there are no crashes, maybe it gets increased a bit. If there are crashes with severe injury or fatality, then it gets reduced. We don’t need to change speed limit signs, we just change the permissible speed which vehicles respond to and follow.

Of course we should redesign streets to make them friendlier and safer for walkers, bicyclists, transit users, and drivers for that matter. But in the meanwhile, I want no one to die or be seriously injured on the streets and roads we have. Speed-limiting is the solution.

It is worth pointing out that designers and manufacturers of autonomous vehicles don’t want this to happen. They are assuming they will be allowed to violate speed limits, because they know that their primary target driver audience, young aggressive males, won’t buy vehicles that go the speed limit. They are just hoping no one notices that they are going to bypass this, and probably will get away with it.

Would it be easier to speed-limit vehicles?

In my previous post, Yes, and lower speed limits, and many others, I’ve written about speed and and need to reduce vehicle speeds. This can be done in a number of ways, most effectively by redesigning streets. But street redesign is a multi-billion dollar undertaking just in our region, and that is a conservative estimate.

Thinking outside the box, what if we speed-limited vehicles instead? What if all vehicles were limited to the posted speed limit? Many newer vehicles already have most of the technology needed: cruise control and location awareness through GPS. They would need some modification to use the cruise control to limit the speed, not to what the driver sets it at, but what the speed limit is. Shouldn’t cost much money for the conversion. Old vehicles, of course, don’t have this technology, and would need a fairly expensive update. How expensive, I don’t know. I’m not a technology person, and can only express surprise that either researchers are not researching this, or that if they are, it isn’t making it into the media.

During the transition period, I can see two actions that would encourage conversion. One is similar to emission inspections, where once your car becomes unable to pass inspection, and it would cost more to fix it that it’s value, it is retired. Of course in California, that means the car is shipped to another state to keep polluting, and that is not a good solution. The other is that there would be a penalty for not installing the conversion. The penalty would gradually increase over time. There are very obvious equity issues about this proposal. Maybe a cash-for-speeders program to buy and retire vehicles without speed-limiters. And it is not as though our current system is without equity implications. People of color and low income are much more likely to be the victims of crashes as are others, and we certainly know that speed enforcement can and is used to oppress people of color and low income.

Speed-limited vehicles would be a huge investment, for the updates required of newer vehicles, and the addition of the technology to older vehicles. I strongly suspect that it would be much less than the investment of fixing all our streets. Of course, we eventually still want to fix our streets in locations that are not triaged out, to make them livable and economically vibrant places, but with speed-limiting, we would have more time to work on that.

I would exempt two-lane rural roads from speed-limiting. Though a lot of crashes do occur on these roads, the valid need to be able to pass slow moving vehicles remains, and the scheme would just not work here. All other roads, yes. It might even be possible to increase speeds on freeways, where variability in speed is as much of a problem as speed itself.

Of course cars-first people would scream that this attacks their god-given and constitutionally-guaranteed right to drive as fast as they can. But these are the car nuts, just like gun nuts, that claim a right to do what they want to do without any consideration of the effect on others. It is time we grow up and recognize that vehicles are deadly weapons that must be limited to reduce mayhem.

Will autonomous vehicles solve this problem? Perhaps. These vehicles will certainly have full awareness of the posted speed limits on every street (part of the reason they are bandwidth intensive). I suspect that most autonomous vehicles will be part of commercial fleets (buses, delivery vehicles, ride hailing). Given the legal liability of allowing these vehicles to exceed the speed limit, I don’t think companies will. Of course there will be private owners who hack their autonomous vehicles to exceed the speed limit, but in a world of speed-limited vehicles these will stand out and be dealt with. The real issue, though, is that there will be a very long period of transition in which most vehicles on the road are not autonomous.

I welcome comments from anyone more technologically savvy than I, who can help me better understand the technological issues and solutions.