A short item in New Atlas describes a new bus prototype from Swedish automotive giant Volvo. The new bus is equipped with a system called the Pedestrian and Cyclist Detection System (PCDS).
The PCDS combines cameras attached to the bus with a program that anticipates danger to cyclists, pedestrians, and other mobile "obstacles" to bus travel. When a collision appears possible, the bus makes a noise to warn the pedestrian, etc. The horn is used if the risk is deemed to be very high.
Also, an alarm is sounded and flashed on the dashboard to alert the bus driver.
The effort to protect people potentially menaced by the bus is praiseworthy. Most of the time, improvements in automotive safety have focussed on occupants. However, cars and busses can be quite dangerous for other users of the roadways. So, making them safer for others helps to increase equity of risk for them, meaning that every legitimate user of the road comes to face a similar level of risk.
One challenge for achievement of this goal may be risk compensation. On this hypothesis, people are comfortable with a certain level of risk in a given activity. Thus, when a safety feature is introduced into their lives that makes that activity safer, people tend to behave more recklessly, thus returning the level of risk to their accepted level.
This effect is held by some researchers to have neutralized safety advantages that were supposed to result from the adoption of anti-lock brakes.
So, it may be that drivers of busses equipped with PCDS will drive more recklessly, perhaps to the point of neutralizing any safety advantages that the system would otherwise produce.
A similar problem is that bus drivers may feel that any additional safety margin provided by the PCDS gives them the opportunity to be more productive by engaging in other activities.
For example, a man was recorded evidently sleeping while his Tesla drove itself down the road in Autopilot mode this May. Apparently, he had decided that since the car would keep him pretty safe, he could spend his time more profitably by sleeping than by paying attention.
Similarly, drivers of PCDS-equipped busses may decide that since the bus will warn them of impending collisions, then they could use their time to pursue more pressing goals, such as playing Pokémon.
A third possible problem might arise with a diffusion of responsibility. This refers to how people may feel less responsible than otherwise in a situation where others are present. For example, people walking along a street may decide not to help someone who has fallen because there are others nearby who can do so (and often, are not helping for the same reason).
If a bus with a PCDS system installed issues warnings autonomously to pedestrians and cyclists in its vicinity, then drivers may feel that it is more the responsibility of those people to get out of the way than it is the driver's responsibility to avoid them. After all, the bus did honk at them!
Feeling less responsible for the safety of others, drivers may not be as careful around them as they otherwise would be.
I suspect that Volvo is aware of these issues and will assess effects of the PCDS on drivers' behavior. It will be interesting to see how any such problems may arise and be dealt with.