The stark reality is that the risk of death in the case of a crash is three times higher for night driving than for clear visibility conditions. How far can we see, and what does this distance mean?….

Headlights                               dims                                        main beam

Visibility range (cut off point)

Velocity at 120kph                        45m                                         100m

Available time                      33m per second                          33m per second

Note that all the time you have while on dims after seeing the object, is 1.5 seconds - on main beam  3 seconds. This is only the beginning. When one encounters a hazard on the road, one goes through the following five steps before brining the vehicle to a halt :

• Perception of the hazard, under poor visibility conditions

• Identifying the hazard under poor lighting conditions

• Deciding from the alternatives available, and what action to take

• Reaction time - mental plus muscular

• Braking

Each step takes time and uses up the available seconds. The biggest problem of all is still to come - this is highway hypnosis - leading to a condition known as 'auto pilot'. All of this adds up to HIGH-RISK, night driving. It is terrifying to think of the 1.5 seconds visibility, as well as the threefold increase in the probability of death in the case of an accident.

STOPPING DISTANCES

Headlights                               dims                                        main beam

Visibility range(cut off point)

Velocity at 120kph                        45m                                         100m

Available time                       33m per second                         33m per second

A wet road requires even greater distances. If we add time for perception and recognition at night, we overshoot the 200 mark. If we now add auto-pilot, wake-time of 3 seconds, then we are well into the 300m - 400m range. Yet our range of visibility stays at 45m and 100m - ie 1.5 seconds and 3 seconds respectively.

Highway hypnosis is the process whereby the mind gradually switches off due to lack in input stimuli. The driver at first resists the process by searching for some input, but all he sees is blackness. It is this blackness that wipes away a major clue to distances - the geometry of the scene.

After a while he finally gives up and the minds access system ceases to respond. The driver is then left holding the steering wheel, and keeping the vehicle centered on the grey tarmac strip, a condition known as auto-pilot. When a turn appears all he has to do is keep the car centered. The other functions are effectively disabled, and he is not able to respond to an emergency in time.

Remember all the issues operating under these conditions:

Absence of geometric clues, highway hypnotism auto-pilot, 33m/sec if traveling at 120kph, 45m dim range, 100m main-beam, veiling glare, night-time coefficient values, nighttime vision recovery and finally the visibility and effectiveness of current hazard warning devices when surrounded by streams of flashing red and amber tail lights, and rows of dazzling headlights - dims, as well as main beam, and flashing headlights.