VMS
Variable Message Signs
VMS types
VMS
with predefined number of signals
Freely
programmable VMS
fully
graphic full colour signals
lane
control signals
combined
signals
DRIP
Dynamic Route Information Panels
Guidelines for requirements on VMS
Example 1: Highway (Motorway), straight lanes, Speed- and attention signs, Lane use signals, Legibility 200m
Colour: C2
Good visibility even for people who are weak on
determining red colour, also no problems when sunglasses are
used
Luminance: L3(*)
For having enough power for good visibility on large
distances at poor conditions high luminance is required; in the
evening and at morning
at low sun signs are still good visible
Luminance ratio: R3, R2 High Contrast against the
environmental background is condition for good legibility
Beam width: B1
Signs are only seen from the front (on axis), low beam
width (for sign-width below 2m) is focussing the light to higher
intensity, excellent legibility can be guaranteed from 200 to 35
meters
Other requirements:
No
front screen (Refledtions, pollution, aging, loss of
transmission, moisting up)
Flat
front (no pollution of optical part)
Lenses
are pressed in from the front-side (water tight against high
pressure cleaning)
No
multiplexing (LEDs
are never not even for short time driven with higher current
then
stated, which is promoting lifetime and avoids
again aging
How
can the supplier guarantee the stability of the light output for
the working period of the sign,
LEDs should never be stressed above 40% of the
allowed current
Example 3: Highway, straight lanes, Large Traffic
Information panel, Legibility 200m
Colour: C2 Good visibility even for people who are weak
on determining red colour, also no problems when
sunglasses are used
Luminance: L3(*) For having enough power for good
visibility on large distances at poor conditions high
luminance is required; in the evening and at morning at
low sun signs are still good visible
Luminance ratio: R2 High Contrast against the
environmental background is condition for good
legibility
Beam
width : B2 or B3 By using smaller pixel distances on
free programmable information signs it is possible to
reach high luminance and higher beam width at the same
time. Good Legibility on a distance between 200m and 35m
Other
requirements:
No
front screen (Refledtions, pollution, aging, loss of
transmission, moisting up)
Flat
front (no pollution of optical part)
Lenses are pressed in from the front-side (water tight
against high pressure cleaning)
No
multiplexing (LEDs are never not even for short time
driven with higher current then
stated, which is promoting lifetime and avoids again
aging
How
can the supplier guarantee the stability of the light
output for the working period of the sign,
LEDs
should never be stressed above 40% of the allowed
current
