Cars In The Future : Vehicle Conspicuity
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Vehicle conspicuity is an important issue; the theory goes that the sooner other road users see you, the more time they have to respond. It is not a replacement for safe driving however – a dangerously driven silver car will be just as dangerous as if the car is black. Advantages of conspicuity are lost if drivers do not make safe predictable choices.
Conspicuity in the future will be achieved by more methods than just visibility of vehicles and car-to-car communications and other methods of detecting the road users location will be employed in future.
Daytime Running Lights (DRL) are a way of improving vehicle conspicuity in the daytime; they draw further attention to the vehicle from other drivers making observations.
A technical implementation of daytime running lights would be a bulb close to each headlight that are automatically illuminated by the ignition system. The bulbs are energy efficient and are of a lower intensity than full headlights, as they do not need to illuminate the road, their purpose is to be noticed by other road users. This reduces the environmental impact of having the lights permanently on.
Recent studies have shown that DRL would be highly effective in reducing the number of casualties on the roads. TNO conducted a meta-analysis based on 25 past studies of DRL, it was hoped that the wide range of methodologies analysed in the past studies, as well as the consistency of the results from them, would lead to a highly accurate figure. It concluded that the overall net reduction of accidents would be 5.9%.
The hypothesis that this reduction in accidents as a result of the use of DRL may be a novelty effect was also studied in the TNO report. It concluded that, although there were indications that this might be the case, the evidence is inconclusive.
There is major concern that the adoption of daytime running lights by all road users will diminish any advantages that are currently received by motorcyclists that use daytime running lights. This concern also extends to other road users whose conspicuity may suffer alongside a car using DRL, such as cyclists and pedestrians.
Current research by TNO on the issue sums up the concerns stated by previous analysis into three categories, based on the hypothetical conclusions on how DRL will increase conspicuity.
- The adverse effects of DRL due to higher conspicuity. This describes the concerns by motorcyclists that the adoption of DRL by all vehicles would lead to a reduction of a motorcycle’s conspicuity. This is because as all road users become more conspicuous, motorcyclists – who are already less conspicuous than cars due to colour and shape – will become less conspicuous relative to that increase.
- The adverse effect of DRL due to a consistent search feature. This is related more to the psychology by which drivers make observations rather than the conspicuity. When making observations, people tend to search for specific features rather than survey the entire scene, be it shape, colour or luminosity. By creating a specific feature on all vehicles that drivers can look for – such as DRL – it decreases the reliance on searching for other features, and thus the chance that a road user without DRL is spotted.
- The adverse effects of DRL due to a feature for identification. This is again related to the psychology behind DRL, a driver making observations may notice a vehicle without DRL, but not identify it as a hazard due to it’s lack of DRL.
The TNO report conducted experimentation to see if any of the three hypothesised effects manifested themselves in an experimental scenario. The tests were conducted on a variety of subjects who were asked to survey scenes of varying complexity in order to mimic a real life traffic scenario.
The conclusions of the experiment were that the conspicuity of other road users did not suffer, in terms of the time taken until their detection. The report concluded that although it is impossible to test every combination of possibilities and complexities on the road, if there was an overwhelming adverse effect upon the conspicuity of other road users then it would have shown up within the data under review.
This is a positive result, and should go someway to alleviate the concerns of motorcyclists. It shows that the increase in risk that DRL poses to motorcyclists is small and was un-measurable.
Although the risk posed will never proved to be zero, as there is always risk, by working with motorcyclist groups and representatives, a solution needs to be found whereby all road users would benefit from this technology, and are comfortable with the solution.
A viable solution to any concerns of the potential reduction in the effect of motorcycle DRL’s could potentially be addressed by fitting cars with low intensity daytime running lights and for motorcyclists to use dipped headlights.
Certainly, the debate on DRL needs to be re-opened, and research specific to this country needs to guide it - as a potential 5.9% reduction in all accidents is a significant figure that should not be ignored.
Vehicle lighting systems are set to improve into the future - the better the illumination, the more chance a driver has of spotting hazards and planning to avoid them.
Adaptive lighting system swill make the lit area more relevant to the environment that the vehicle is in as well as improving the quality of the illumination. When waiting at junctions, for example, the lights will illuminate the area to the side of the vehicle so that the driver can see if any pedestrians are waiting to cross, or when going around a corner the lights will angle themselves to illuminate the direction that the vehicle is heading, not the direction it is facing.
It is important that both discomfort and disability glare is taken into account, so as not to put other drivers at risk. There is such a thing as ‘too powerful’ where vehicle lighting is concerned.
Protocols such as PNCAP will help to standardise the areas lit by vehicle headlights and this information could be fed back to road engineering to standardise the location of road signs.
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