Research Project

Evaluation of Auto Dipper from Safety Point of View

Dinesh Mohan and Sudipto Mukherjee

Project Details

Scope of Work

To assess the state of the art information on the effectiveness of auto dippers with respect to road safety, including work done abroad.


In the case of the rule mandating the use of the "auto dipper" in India, the essential stages of the necessary rule making process have been missed out completely. In fact, a technology was made available first and then attempts made to justify it. Since this technology does not have any scientific validation from any where else in the world, it is important that we review the whole process so that we are certain that the society is benefited and not harmed by this rule.


The accident data from India show that both on urban roads and intercity highways in India the traffic is highly heterogenous. Four-wheelers comprise much less than 50 percent of the vehicles in cities and generally less than 60 percent on highways. The accident data indicate that there are a large number of pedestrians also present urban and rural roads. Crashes involving 4-wheeled vehicles, especially buses and trucks, with vulnerable road users (pedestrians, bicyclists, and motorcyclists/scooterists) are the dominant types of crashes both on highways and inside cities. Any accident prevention strategies must give the maximum importance to the prevention of these types of crashes The fact that a large number of vulnerable road users get hit by 4-wheelers at night means that there is a need for better detection of these road users at distances which are adequate for safety manoeuvres like braking. Consequently, any measure that reduces the visibility distance of drivers of four-wheelers is likely to result in an increase in accidents. Headlight use policies should focus on integration of standards for all vehicle types, increase in detection capability of vulnerable road users on the left side of the road, and increase in the intensity of light to detect smaller objects at greater distances at night


An exhaustive review of papers on road accidents in India published in the last twenty years has also been done to understand the factors associated with crashes on urban and rural roads. In this review, not a single study was found which identified the problem of glare in a scientific manner as a factor associated with a significant number of road accidents at night. Therefore, if a scientific process of rule making base on available data was followed, there would be no case for mandating the use of "auto dippers" at present as we do not satisfy the requirements of the first stage.

Distinction must be made between temporal glare effect, disability glare and discomfort glare. Temporal glare is due to an abrupt change in the adaptation level of the driver (e.g. looking at the headlights of an oncoming car at night, entering an unlit tunnel in the daytime). Disability glare arises as a spatial static effect when a glare source is present in the visual field. Discomfort glare is purely a psychological effect. The discomfort felt by the driver and his ability to cope with the situation would be a weighted sum of the different types of glare, and this would differ from person to person. In this situation the subjective evaluation of each individual regarding the situation and his needs for coping with it in terms of intensity of light needed for discrimination of objects would also differ from person to person. These findings have important implications for headlight policy making. Because of the different kinds of glare effects, only the driver can decide how much light he wants ant any given time. Any mechanical device sensing light intensity a t a fixed height will be completely inadequate. Secondly, since the glare effect reduces much before the vehicles pass each other, it is very difficult to decide mechanically when a headlight should be on high beam or low beam.

Since bicycles in India do not have tail lights and most of the victims are bicyclists and pedestrians we have to be very careful with any measure which reduces the visibility distance of the driver of a motor vehicle . The current international research efforts are aimed at increasing the visibility distance and not decreasing them. None of scientists working in the area of visibility and safety even mention the use of "auto dippers". Instead, those working with very sophisticated devices like head up displays, night vision instruments and intelligent vehicle systems have not found an alternative to letting drivers to self select when to interact with these devices.

A review of international opinion reveals the following:

  • The "auto-dipper" is not required in any of the European countries or U.S.A.

  • At present there is no research being done in Europe on "auto-dippers"

  • There is no move to introduce the "auto dipper" in Europe at any time in the future

  • There are no recent publications on the subject.

  • Glare is not well defined for counter measures like "auto dippers" to be made mandatory

  • The use of "auto dippers" is likely to increase accidents involving vulnerable road users

  • None of the experts recommend use of "auto dippers" in India

  • They recommend that vehicles should drive with the high beam when roads do not have street lights.

  • They recommend that drivers should alternate between high beam and low beam when two vehicles approach each other.

The above findings are supported by a report submitted byThe Automotive Research Association of India on the subject of "auto dippers". In this report they state:

  • "As per the information available to the sub-committee, the fitment of Auto-dipper is not a mandatory requirement in any other country in the world and no vehicle manufacturer in the world provided Auto-dipper as an original mandated equipment."

  • "Efforts done by international community like Inter Europe indicate that "The problem of dazzle cannot be solved by the automatic dipping". They have felt that "Eliminating dazzle is not so much a matter of switching but rather depends on correct headlamp settings, a factor that no automatic system can influence.""

Before the start of work on designing and testing "auto dippers", an assessment should have been made on how many road users are killed an injured in India because of the problem of glare and dazzle. This was not done. Our review of literature on epidemiology of road accidents in India shows that there is not a single study which quantifies the problem of glare and resulting accidents in a scientific manner. Therefore, initiation of the process to introduce "auto dippers" in India is not valid on a technical basis.

The designers of "auto dippers" in India appear to be ignorant of the voluminous literature on vision research, issues concerning perception and the driving task and the complexities involving different types of glare. If they were aware of this they would have known that: (i) the measurement of intensity of light at a point in the vehicle cannot be an adequate measure for judging what the driver actually sees, (ii) the effect of glare on a driver’s visual perception does not depend only on the intensity of incident light from headlamps but also the optical properties of the road and the objects on the road that the driver wants to detect, (iii) the effect of glare changes as two facing vehicles approach each other, and for reasons of safety it would be better for lights to be switched from low beam to high beam before the vehicles cross each other. These are just a few of the issues which have not been considered. Since the "auto dippers" have been designed in the absence of scientific knowledge concerning safety and glare, it is logically not possible for such instruments to be even theoretically efficient in solving the problem. In such a situation there was no need to waste time and effort in testing and evaluation.

All the trials done up to now only test the switching capabilities of the "auto dippers" from high beam to low beam and vice versa. These tests have no validity as they do not test the accident avoiding capability of the drivers using vehicles equipped with the devices. The test track trials should have involved comparison of small unlit object avoidance by drivers with and without "auto dippers" in different traffic, road and visibility conditions. It is important to understand that safety devices can only be recommended if they reduce the probability of the occurrence of crashes. The design of all the experiments and trials done up to now are invalid as they do measure the probability of reduction in accidents. In our opinion the trials done as of date just established whether the instruments function according to the specifications of the manufacturers, but these tests do not in any way prove whether the "auto dippers" can be considered a safety device.

An analysis of avoidance capability of drivers shows that a large number of pedestrians and other inconspicuous vulnerable road users would get killed by vehicles travelling at 50-80 km/h with headlights on low beam. On the other hand they would be much safer if the same vehicles had their high beam on. Since these velocities are normal cruising speeds in India, the introduction of "auto dippers" are likely to increase the number of fatalities and injuries in the country.

In conclusion we can state that the trials and tests done on "auto dippers" have not been done in a logical manner with no adherence to established scientific and statistical norms followed all over the world.


The introduction of a new road safety device must follow the same norms as when a new drug is introduced in the market. To understand this process regarding the mandating of the fitment of "auto dippers" on four-wheelers in India, we have reviewed the international literature available on the subject, obtained views of international experts, examined all the documents submitted by automobile and "auto dipper" manufacturers and reviewed reports on all tests done. Based on this analysis we give a summary of the process which should have been followed and what has actually been done.

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