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Photo: Camilla Grane
Prototypes that have been used to investigate the utility of various gear systems in the project Life on board, a collaboration between Luleå University of Technology, Volvo Cars and Kongsberg Automotive. Photo: Camilla Grane View original picture , opens in new tab/window

Traffic Hazards gear systems

Published: 9 March 2016

The traditional mechanical automatic gear shifter systems in cars, where the hand senses when a new gear jacks in, has got a contender through the new electromechanical shift-by-wire systems. New studies at Luleå University of Technology show that it takes much longer to engage a gear with the new systems, which can affect road safety.

- If you are in a difficult situation and, for example, need to quickly reverse the car, because you run too far out on the railroad tracks, it must not take long to select the right gear. The difference in gear selection time that we see between transmission systems in our studies is so large that it can affect the risk of accidents in a critical situation, says Camilla Grane, researcher in Engineering Psychology at Luleå University of Technology.

More difficult to switch quickly

A similar critical moment can be when a driver should drive onto a major road and an oncoming car at high speed forces the driver to make a new choice, which involves reversing the car fast. With the new electromagnetic shift-by-wire systems, it generally takes much longer time for the driver to get into the right gear, than with the traditional mechanical systems. The new systems demand more cognitive attention from the drivers and make them more hesistant. Worst results had re-bouncing, so-called monostable shifter systems. The difference in the Luleå researchers' studies show that a driver with a monostable shifter system, would need about 35 meters  additional distance to the approaching car, to reverse and avoid an accident in time, than if the driver had a "classic" polystable gear shifter.

- Although we know that many accidents have occurred because of the new types of gear shifter systems, it was surprising that they caused so many unnecessary problems, distraction and confusion for the drivers, as our studies clearly showed, says Camilla Grane.

Neater look

The studies on various types of gear shifter systems have been made in cooperation with Kongsberg Automotive and Volvo Cars. 72 persons participated in various laboratory experiments and field studies, and 23 different switching systems have been tested.

There is a paradigm shift in the automatic transmission systems in cars towards electromechanical solutions and that is why researchers and the automotive industry focus on this issue. The old mechanical systems where the driver, by means of a lever, moves around the gears of a transmission, are limiting the design and placement of the gear shifter in the car. With the new electromechanical shift-by-wire systems, automotive developers can get a completely different freedom in terms of location, design and appearance of the gear system and the cars can be cheaper to manufacture. Many car manufacturers use the possibility to create new innovative or expressive gear shifter systems. That these new gear shifter systems sometimes confuse the drivers and also cause traffic accidents are internationally recognized.

The car rolls backward

- What is worrying is that there are no guidelines for how the new gear shifter systems should be designed on the basis of road safety. There should for example be guidelines for how long a shift should take for the driver. Some errors caused by the new monostable systems in traffic should not even be possible. A wellknown error with new shifter systems is that the car rolls away when parked, because the driver failed to engage the parking mode. It should not be possible to leave the car in driving mode or reversed driving mode, says Camilla Grane.

Researchers at Luleå University of Technology intend to do follow-up studies and then also include shifter systems for self-driving vehicles and heavy vehicles in the studies.