Are Higher-Performing Road Markings a Cost-Effective Investment in Safety?
Road
markings play an important role in road safety and optimizing the use of road
space. They help provide information that cannot be easily conveyed using
mounted signs. Moreover, signage applied directly to the road surface offers a
form of continuous messaging which can be observed when a verge-mounted sign is
concealed.
Road
markings are available in a variety of formats, including spray, thermoplastic,
screed, and extrusion, but all have to fulfill stringent visibility
requirements.
Recent
collaborative European research has established that the minimum distance at
which road markings should be visible to drivers must be equivalent to two
seconds of travel time. Several factors decide the distance at which a road
marking is visible. Most of them are related to the driver, for example, the
driver’s vision, headlight strength, car cleanliness, or are unavoidable, for
example, rain or glare from oncoming vehicles. However, the composition of the
road marking can be designed to optimize its visibility in a variety of
conditions. For instance, the bright color of road markings is maintained by
using titanium dioxide pigment, and the accumulation of dirt on markings can be
prevented by adding crystallized titanium dioxide. Such accumulation of dirt on
markings is likely to reduce their visibility.
The
majority of the light emitted by the headlights, which hit the surface of the
road, is either reflected forwards or absorbed by the road surface itself with
just a fraction of the light reflected back towards the driver's eyes. Retro-reflection
is referred to as the reflecting of light back in the direction of the light
source. As the coefficient of retro-reflected luminance increase When the
light from the headlights which a road marking reflects back to the driver is
more, the visibility of the road marking will also be more, particularly in bad
weather and at night.
Additives
such as titanium dioxide and others do not create retro-reflection to improve
the luminescence of road markings. On
the contrary, retro-reflection is increased by the addition of glass
beads, thereby enhancing the night-time visibility of road markings. After the headlight beam enters the glass
bead, it hits the pigmented road marking and is reflected back towards the
driver of the car. As a result, the road
marking appears to light up and hence the visibility of the road marking is
considerably increased. Road markings,
which include high-performance glass beads, are five times brighter than road
markings that do not.
The
level of retro-reflection attained by glass beads is decided by the quality of
the glass and the size of the beads. The
30 meter geometry is used to determine the level of retro-reflectivity. This is the amount of reflected luminescence
at a driver height of 1.2 m, an illumination distance of 30 m, and a headlamp
height of 0.65 m.7 It is recommended to have a minimum retro-reflectivity
of 120 mcd/m2/ lux on a dry surface.
Usually,
the glass beads used in road markings have a refractive index ranging between
1.5 and 1.9. They are developed in a
wide range of sizes from 100 to 1500 microns in diameter and with different
degrees of roundness. During production,
glass beads can be combined into the road marking material (intermix beads); can
be added when the road marking is applied (drop on beads); or can be applied to
the surface of newly applied road markings before they have set (drop-on
beads).
It
is important that the beads are embedded by at least 50% of their diameter to
make sure that they do not become displaced.
However, the level of retro-reflectivity is reduced upon increasing the
degree of bead embedment; therefore it is necessary to achieve an effective
balance. It is expected that some of the
beads will become covered with the marking material but this will soon be
removed by passing traffic.
In
addition, the quality of the retro-reflection produced by the glass beads
relies on the roundness and size of the beads, the viscosity of the road
marking material, and the amount of beads added to the road marking. The larger beads with smoother, more round surfaces
enable the highest retro-reflective performance. An effective distribution
level of glass beads is 400‑600 grams per
square meter of road marking.
TORY, a
global leader in high-quality precision glass technology, manufactures glass
spheres for a variety of applications. TORY provides high-quality glass
beads, which can be customized to meet the specific
requirements of customers and projects. TORY manufactures glass beads
that are suitable for improving the visibility of road markings to tight
specifications that ensure optimum reflectivity.
To know more: https://www.cntory.com/
Feel free to contact us:
Email: Echo@cntory.com
WhatsAPP: +8617355287086
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