What Drives Comfort in a Vehicle?
The fact that car manufacturers are competing based on display sizes and massage seats implies ride and handling have reached a point well above consumer expectation. While cars strongly improved in recent decades, roads rather deteriorated because of increasing load (both in quantity and weight of vehicles) and poor maintenance. Nowadays, the single biggest source of discomfort is not in the car but the road.
For the road owner, cracks in the top layer are the most important defect. Cracks lead to water infiltration, resulting in foundation problem and frost damage. Yet, the car (driver) doesn’t feel these cracks. What makes driving really uncomfortable are defects such as:
- Waviness: Especially on faster roads, the combination of speed and uneven road construction results in uncomfortable vertical body motion, ultimately leading to car illness. Apparently, the road may look good but low frequent height variation of the foundation makes the car bounce. The highest frequency waviness can be found as small waves in the asphalt at traffic lights where cars strongly brake.
- Potholes: Luckily potholes do not happen too often or are closed relatively quickly. The most annoying type of potholes are wide gaps in the asphalt top layer. As the top layer is thin, these holes are not deep. As a result, they are not repaired quickly and are allowed to grow in size. The irregular shape and occurrence can shake up a car significantly.
- Rutting: driving in ruts pushes the car in lateral direction, resulting in a very unsafe feeling. It makes the car dance unstably on the road, let alone the risk of aquaplaning.
- Open expansion joints or non-contiguous concrete slabs: Sudden changes in the height profile of the road have a big impact on driving comfort. A height difference of just 1 centimeter feels like a small collision. On concrete slab roads, this effect often occurs with an annoying cadence.
- Poor road repair: Probably the biggest source of discomfort. Mostly local repairs are closed poorly, resulting in bumps, subsidence, and unevenness. Roads with many small repairs result in a very different road profile for left and right wheels, destabilizing cars and strongly impacting the comfort in the car.
All these defects have in common that they are geometrical problems. These are all types of non-flatness, either low-frequency or high-frequency.
While cracks can be seen by cameras, unevenness cannot. Cameras do not have enough depth accuracy and there is not enough structure in the road to recognize and quantify non-flatness. The front view camera in your car or mobile mapping with smartphones or expensive 360° cameras will not help in understanding where poor road geometry impacts our driving comfort (most).
The only suitable solution is high-resolution 3D measurements based on (laser) light. A direct 3D scan of the road surface reveals the complete geometry from which all relevant defects can be recognized, quantified, and located.
Moreover, such systems do this so much faster and more objectively than human inspectors could do.
You can spend your money on massage seats to ease the pain in your back. That is the best your car can do for you. You can ask or hope your (local) road authorities use appropriate tools to have their roads digitized and analyzed so road maintenance budgets are used in a much more effective way. This may save you the investment in massage seats.