A Self-Learning Manual - Institution of Engineers Mauritius

A Self-Learning Manual
Mastering Different Fields of Civil Engineering Works (VC-Q&A Method) Vincent T. H. CHU
reasons (based on Arthur Wignall, Peter S. Kendrick and Roy Ancil):
(i) They provide strength to the sides of road pavements and avoid lateral
displacement of carriageway due to traffic loads.
(ii) In terms of road safety, they serve as a separation line between footway
and carriageway and aid car drivers in driving safely.
(iii) They act as a vertical barrier to guide the surface runoff collected in
road pavements to the gullies.
Fig. Gully grating
16. What is the purpose of road studs in roads? (ORF5)
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.
17. What is the importance of glass beads in road markings? (ORF6)
Retroreflectivity refers to the part of incident light from headlights of a
vehicle being reflected back to the driver. Retroreflectivity is normally
achieved in road marking materials by using glass beads or ceramic beads.
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