accurate systems can ensure their
technology is given the recognition it
deserves, while road authorities can
have more confidence in the
purchased product.
A number of specifications exist
that seek to help in the certification of
WIM systems. The COST 323 report
provides guidance for creating
a WIM standard but has never been
given official approval so holds no
weight legally and merely serves as
a reference point that systems
can be judged against. In
contrast, ASTM 1318 does
constitute a formal standard
but is only valid in the US
and has no recognition on
the international stage.
A third is provided
by the International
Organization of Legal
Metrology (OIML) and though there
doesn’t yet exist one global standard,
Omnidirectional weighing
| WIM Standards
New sensors are overcoming some of the obstacles of previous generations
of the technology, offering greater versatility and ease of maintenance
Weigh-in-motion
(WIM) systems have
notoriously struggled
to overcome the challenge
of accurately weighing fastmoving
vehicles. Cross Zlín’s
brand new OptiWIM sensor
may have overcome them.
Unlike many other products
on the market, the OptiWIM
sensor doesn’t require vehicles
to drive in a straight line.
“If they drive on the hard
shoulder or in between lanes
we don’t care, our sensor can
weigh the truck wherever it is
on the road,” explains CEO and
founder, Tomas Jurík.
Capable of providing an
accuracy of +-5% of gross
vehicle weight, the OptiWIM
achieves this precision with
just one strip of sensors, in
contrast with the multiple
strips typically relied on by rival
systems. Easily fitted on a road,
they are also easy to maintain.
“For all of our competitors to
change a sensor you have to
dig up the road, damaging the
surface,” says Jurík. “But our
patented U-shaped sensor bed
it is the OIML R134 that is closest to
being that standard.
Weighty concerns
As much as the R134 is a source of
pride for those that achieve it, it is not
without controversy and is in fact
a bit of a hot button topic among the
international WIM community.
“This standard is done very
poorly, I am totally against it,” states
Tomas Juřík, CEO and founder at
traffic technology company Cross
Zlín. “Cross Zlín has never used
OIML and until it changes we are not
interested in it,” he adds. Instead
Cross Zlín’s new OptiWIM system
(more on which above) has local type
approval from the Czech Metrology
Institute, the CMI.
An important difference between
R134 and the other two is the margin
for error is smaller: Each measurement
must be within a permitted boundary.
This contrasts with COST or ASTM’s
recommendations that only consider
95% of the measurements.
Gregor Jamnik, a sales manager at
Cestel, shares Jurik’s frustrations:
“The OIML R134 is the only certificate
that you can put in a sales document
to advertize to customers so it is good
to have, however, it is so difficult to
achieve and so expensive that many
companies just do not have it.
“There are some requirements in
the standard that are not very well
defined and, given the variety of
WIM products in the market – with
piezo strip sensors, bending plates
and bridge systems – there should be
an acknowledgement of the different
approaches to producing accurate
WIM systems,” says Jamnik.
Accepted with caveats
Whereas the static scales OIML
certificate (R76) is unconditionally
accepted across many different
nations, the situation concerning
R134 for WIM systems is somewhat
more complicated. In part, due to its
lack of detail – at 140 pages long, R76
is twice the length of R134 – different
The US may not implement it
but if you do business anywhere
outside the USA it is by far the most
referred to standard
Jon Arnold, market specialist, Intercomp
can be replaced with just
a screwdriver.”
And, in the age of the electric
vehicle, the OptiWIM has been
designed to be resistant to
electro-magnetic pulses that
can traditionally affect or even
damage sensitive sensors.
www.TrafficTechnologyToday.com 019
July/August 2019 Traffic Technology International
Above: Cross Zlín’s
OptiWIM sensor
being installed in
a road surface
/www.TrafficTechnologyToday.com