The Supreme Court Monday permitted armed forces, Delhi Police, ambulances, fire and other emergency services to have red beacon lights on their vehicles besides other colours depending on their operational requirements.
A bench of Chief Justice H.L.Dattu, JusticeA A.K.Sikri and Justice R.K.Agrawal permitted the use of red beacon lights by the armed forces and police and other operating emergency services by modifying its Dec 10, 2013 order on an application by the Delhi government.
The order had said that red beacon lights with or without flashers would be used only on the vehicles of high dignitaries as specified in the constitution and white, blue or multi-coloured beacon lights will be used only on emergency services and police vehicles.
"The men in uniform; operational agencies which require unhindered access to the roads for the performance of their duty, those engaged in emergency duties such as ambulance services, fire services, emergency maintenance etc. and police vehicles used as escorts or pilots or for law and order duties shall not be entitled to have red lights but lights of other colours e.g. blue, white, multi-coloured etc," it had said.
Seeking the order's modification, the Delhi government, citing the Rayleigh Theory that the intensity of the light is inversely proportional to the fourth power of wavelength, said: "Red light has maximum wavelength and thus has maximum scattering of incident light. Red light thus has maximum penetration even through low visibility conditions such as fog, dust night time."
On the other hand, "blue light has the minimum wavelength and has maximum scattering and least penetration and thus least visibility amongst the spectrum".
It further told the court that "red colour has been traditionally used as a cautionary sign to alert people and systems by police and army" and is therefore best for use by police and army.