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What is the purpose of road studs in roads?

In nighttime, car drivers could not see where the road ends and where the alignment of road changes in direction. Without sufficient number of road lightings, it is necessary to provide some means to guide the drivers along dark roads. Hence, in 1933 Percy Shaw invented the cat’s eye (i.e. road studs) which is based on the principle of cat’s eyes. When a ray of light enters the eyes of a cat, the light shall be reflected back towards to the emitting source. As such, with the reflection of car’s headlights by road studs, it is possible to identify road conditions and alignment in darkness.


However, the provision of cats’ eye is not without problem. For instance, there have been reported accidents arising from loosely installed cat’s eye. Some new design of cat’s eye uses LEDs which flash at about 100 times per second. However, it is claimed to cause epileptic fits of drivers.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

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Kanwarjot Singh

Kanwarjot Singh is the founder of Civil Engineering Portal, a leading civil engineering website which has been awarded as the best online publication by CIDC. He did his BE civil from Thapar University, Patiala and has been working on this website with his team of Civil Engineers.

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