On any given day in Bangalore, or for that matter, any city, you will see a lot of drivers using their high beams to drive in traffic. Legally, this is not allowed by traffic regulations. But if one sees closely, many use it more out of compulsion or need rather than intension.

A factory fitted High Beam Throw

Using High Beams to avoid eminent danger

Here’s a list of situations where it is legal to use the high beams or brights.

1. When there is little or no illumination on the road. Like an empty stretch of highway with no illumination and higher speed limits. Use of High Beams are necessary here to ensure safe driving. Lower your beams to let oncoming traffic pass without blinding them.
2. To alert oncoming traffic to lower their beams, only once or twice. This is a nuisance that we face almost on a regular basis. Most under maintained vehicles like Cabs, Buses have inadequate Low Beams compelling their driver to use the High Beams to view the road ahead. You can blink at them with your high beams to ask them to lower theirs.
3. Signaling a slow moving vehicle in front of you to give you way so that you can overtake. This can be done only once or twice and not repeatedly. If the vehicle still does not move, you can conclude that the driver of the vehicle is not alert and can use the Horn to alert them. Large and heavy vehicles, with well sealed cabins can only be alerted by the use of high beams to blink once or twice.
4. When traveling on a high speed limit highway with clearly divided lanes for oncoming traffic. Higher speeds translates to crossing longer distances in lesser time. You need longer reaching lamps to see the road ahead and ensure safety.

Newer technology has brighter lamps that does not blind the oncoming traffic.

Many modern cars are fitted with HID (High Intensity Discharge) lamps and lenses to ensure that the driver gets to see the road without blinding the oncoming traffic. However, use of HID lamps without lenses results in lesser illumination than their Halogen counterparts and just provides white light with very bad throw. Car headlamps are designed to be used with a specific type of bulb, and changing that to a higher wattage, brighter bulb does not always result in better illumination. Such modifications should be avoided or carried out under expert supervision.

A set of projector headlamps

HID high + lo beam in action

In India, the wattage allowed for headlamps are a standard 55 W (known as a 55/60 in open market).

Anything higher that this is subject to scrutiny by traffic police. Though many people upgrade their headlamps to 90/100 or 130/100, these are not legal to be used on paved roads. These lamps are specifically created for extreme condition use only, like forests, muddy terrains, etc. (although many of our Highways qualify in these categories). Use of higher wattage lamps blind the oncoming traffic, and increases chances of traffic accidents.

More details are here if one is interested.