Installation of Fixed Capacitive HSWIM Sensors

Important notes
Refer to the Mikros Systems loop installation document.
The terms HSWIM (High Speed Weighing In Motion) and WIM (Weighing In Motion)
are used interchangeably throughout this document.
All procedures stipulated in the loop installation document are relevant to the
installation of WIM sensors.
Adhere to the required safety and quality assurance procedures.
Install only on an adequate road surface.
Consult a pavement specialist before deciding on the appropriate installation method.
Install the width and the breadth of the sensor, level with and parallel to the road
surface using the bottom of the frame as reference and not the frame sides.
Set the frame 2-3mm below the pavement surface.
Keep water from penetrating to the sub-base.
Only use Mikros Systems supplied feeder wire.
When positioning a sensor, make sure that the middle of the sensor coincides with a
wheel track.
Although this document refers mainly to the 2m WIM sensor al the same procedures
are valid when installing a 1,5m sensor.
Background information
This document should be used in conjunction with “MS001-96200-52 Installation of Loops for
Traffic Logging Stations”, which describes in detail the basics for any type and configuration
of Traffic Logging installations. An in-depth knowledge of this document is a prerequisite.
Site selection is the key factor in a successful High Speed Weighing-In-Motion (HSWIM)
station installation and performance. For the requirements of a HSWIM site refer to the
document “MS001-00005-41 WIM Site Requirements”.
For a proper installation what is of utmost importance is:
Pavement (road conditions)
o Flatness (flushness)
o Smoothness (riding quality)
o Evenness (surface quality)
Traffic behaviour
o Uniform flow
o Lane discipline
To maintain these qualities of installation over a long term only high quality pavements of
ample thickness that are structurally sound should be selected. In lesser pavements the
integrity of WIM data will be compromised. Mikros Systems cannot be held accountable for
the poor performance of a WIM installation that is done in sub-standard conditions.
Mikros Systems recommends that the user of HSWIM equipment also refers to the US
Federal High Way Associations specification document for HSWIM systems, called “ASTM
E1318-94 Standard Specification for Highway Weigh-In Motion (WIM) Systems with User
Requirement and Test Method”.
Figure 1 (see Annexure A) illustrates the general principle of installing a Mikros Systems
Capacitive WIM Sensor.
MS001-96100-52 Installation of Fixed Capacitive HSWIM Sensors Issue5 1 March 2005
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