General Principles

ASTM-E1318 requires that the WIM equipment be installed and maintained in accordance with the recommendations of the system vendors.

Some general principles are:

  • Installation must be done in good weather, not wet, freezing, or hot conditions.
  • The sensors must be flush with the road surface, no more than 1 mm separating the top of the sensor from the road surface.
  • The equipment must be protected from water and dust.
  • The equipment cabinet must protect the system electronics from temperature, dust, humidity, and insect and rodent infestation.
  • The equipment must be protected from lightning and power surges.
  • The equipment must be installed so that routine maintenance can occur without disruption of data collection.

All the necessary equipment, materials, WIM components, site plans should be on the site before installation is started. An example checklist for installation of a WIM system, based on Minnesota Department of Transportation is presented below.

Table: Example checklist for installation of a WIM system
Map and hand sketch of location and layout Roadway history
  • Road Number, crway, SLK, all lanes, shoulder, intersecting roads
  • Relative position to nearest intersection/control point
  • Lane widths, medians, shoulder width, lead lengths needed
  • Power, phone
  • Cabinet location
  • Drainage, ditches
  • Parking spot
  • Traffic management
  • Age of pavement and surface
  • Type of pavement and surface
  • Smoothness
  • Crown

Source: Adapted from Middleton et. al. 2004.

Further Reading 

American Society for Testing Materials, Standard specification for highway weigh-in-motion (WIM) systems with user requirements and test methods, E1318-09, American Society for Testing Materials, West Conshohocken, PA, USA

Middelton, D, Crawford J, Parker R, 2004, Planning for Traffic Monitoring Equipment Evaluation Facility, Texas Transportation Institute, Texas A&M University, Texas, USA.

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