Ratings on pollution and crashes

The way we rate vehicle safety has for a long time been a pet project of mine. VIA plucked me from academia and my experience with cars was limited to the fact that I had owned one previously. I could change a tyre, but that was about it.

What I was good at, however, was doing research. And, just as importantly in academia, peerreviewing the research of others, such as government analysts.

Since I knew nothing about vehicles or the industry, I had a lot to learn but that had benefits – I wasn’t biased by prior knowledge.

From the onset, one of the topics that interested me most was the way vehicle safety was rated. The reason it interested me so much was because it seemed so wrong. Even today, after trying to understand it for a decade, I still find it befuddling and I cannot help but conclude that it’s likely counterproductive.

In general, we base a vehicle’s safety ratings on the ability for it to keep its occupants safe.

Recently, there have been some minor tweaks to this, for instance by taking aggressivity into account, which is the likelihood a vehicle will do harm to pedestrians or cyclists. However, these considerations remain minor compared to occupant safety.

There are several aspects of this system that concern me. First, I’m extremely concerned the public is being misled. The most respected rating system is NCAP, which tests vehicles in collisions with static objects. This simulates a vehicle crashing into itself.

Then, when people walk onto yards, they see five-star small models sitting next to five-star big cars and the false impression given is that they are comparatively safe.

No matter what the propaganda says, physics tells us different. Even a well-rated small car is going to be crushed by a large vehicle of any rating.

KIT WILKERSON

our safety strategy, the view that bigger vehicles are safer for occupants has created an arms race with average vehicles increasing in mass over time. It also creates a zero-sum race.

to protect occupants from air pollution. It seems silly, but it’s the same logic we’re using to gauge vehicle safety for crashes.

There is a debate in the literature on the best proxy for approximating the chance of injury in a crash – whether to use kinetic energy or force.

The problem with kinetic energy is it simplifies the source of the actual injury. Injuries and deaths could occur even if vehicles have perfect crumple zones that absorb all the energy in a collision.

Harm would still occur due to the short time or distance change in velocity from occupants proceeding in the direction of travel until something else quickly changes their movement, hence the force applied to the body in the act of stopping.

When using kinetic energy, mass has a much smaller factor than when considering force, but – in either case – the only two variables are mass and velocity. And only one of those is a feature of a vehicle.

Returning to how this effects

Those heavy vehicles are safer for their occupants, but make roads less safe for everyone else. It means this approach to safety doesn’t actually lead to a reduction in overall harm, only a transfer of harm.

If, on the other hand, we started reducing the mass of vehicles entering the fleet, not only would we see a reduction in overall harm as the potential difference in mass between vehicles that might be involved in a collision decreases, it would have the counterintuitive effect of appreciating the crashworthiness of in-service vehicles every year they would be relatively heavier.

This isn’t even my biggest issue with how we rate safety. My biggest concern is the fact the strategy is irreconcilable with the way we measure and reduce harms everywhere else and, therefore, cannot and should not be part of a unified strategy to reduce harm.

Imagine if our emissions ratings were based on a car’s ability

In fact, just to make the analogy more accurate, imagine we then decided the best way to improve vehicle pollution ratings was to equip them with ever bigger filtration systems.

This, of course, leads to decreasing the efficiency of cars and increasing emissions overall, which in turn demands we fit bigger filters. Hence the arms race, it’s simply absurd.

VIA is now developing a new system that focuses exclusively on ratings based on harm. This system easily accounts for both certain harm from noxious emissions and possible harm from crashes.

Interestingly, the results of this rating system align perfectly with our stated goals for future transport – the least harmful, or highest rated, means of transport being walking, cycling and micromobility devices.

When it comes to cars, electric vehicles (EVs) have a massive advantage due to their lack of certain harm from emissions, but lighter EVs will in turn beat more massive EVs thereby encouraging efficiency.

I haven’t considered adding in climate-change risk factors, but that could easily be done to create a single, unified vehicle-preference rating.

Imagine, instead of a system that simply transfers harm to others, we could have one that actually reduces the sum of harm –silly, I know.