Nowadays customers of bus companies not only want to get from point A to point B, but also want to do this safely, reliably, comfortably and in predictable time.

Comfort means not only convenient seats, but also sensations of the passengers, that is, how they feel the ride when they are seated or when they stand if there are no spare seats. When the road is smooth and the shock absorbers are soft and effective, the main part of those feelings is related to accelerations.
Passengers experience acceleration whenever the bus accelerates or decelerates or makes a turn. The difference is only in the direction of the acceleration.
It appears that the answer (or, at least, one of the answers) to the requirements of comfort, safety, reliability and predictability is the same – smooth driving. Moreover, this is also an answer to the requirements of bus companies to saving fuel and prolonging life of the engine, chassis and elements of transmission.
But how can you make the driver drive smoothly and avoid harsh acceleration, braking and turning? Feelings of the driver differ from feelings of the passengers even though they experience the same accelerations, because the driver knows when the accelerations appear before they appear. Besides, the driver knows why he accelerates or brakes. Passengers do not have this knowledge; for them, all sudden changes in acceleration are unexpected.
In old times and in some countries, passengers would shout to the driver something like "Hey, buddy, not that harsh! You are carrying people, not logs." That was a useful feedback. But now people are very polite or preoccupied with their own business, and do not provide feedback to the driver. They provide feedback to the bus company by walking away from it.
Scientists and engineers in New Zealand decided to provide a feedback about accelerations to the driver using modern technologies. They suggested installing telemetric equipment in the bus and put a small indicator in front of the driver. It shows green light when the acceleration is within the zone of comfort of the passengers, orange when it causes slight discomfort and red when it is too harsh. The telemetric equipment is basically a set of accelerometers and a data processing device, to which the accelerometers are connected. Just over two decades ago accelerometers were too expensive for such purposes and they were used mainly in aircraft and spacecraft. Now they can be found in laptops and even hand-held gadgets.
Critics see an unexpected problem with these devices. They not only show acceleration to the driver, but also send these measurements to their bosses. This may put an additional stress on the driver, which can make their driving less safe, while more comfortable. Proponents of the devices reply to this that if you are a professional (and bus drivers have to be professionals), you have to expect some monitoring of your performance by your bosses, and this must not be a problem.
This text is based on the information presented in the BBC popular science radio programmes.