A (very) brief history of Weigh-In-Motion

WIM was invented in the US (Texas) in the 50s by Dr. Clyde Lee who is the first honorary member of ISWIM. Originally it was mainly used to collect large sample of axle and vehicle loads for pavement design purposes and the ASTHOO pavement design code. Bending plates were among the first sensors used for weighing. From the 70s, new technologies of WIM sensors were developed in Europe, such as wire, strip and bar sensors, capacitive, piezo-electric (ceramic, then polymer and then quarz), and finally fiber optics. Bridge WIM was also introduced in the US in the late 70s and then developed in Europe in the 90s.

In the 70s and 80s, WIM data continued to be used for pavement design purposes and in addition were used for bridge design code calibration (Ontario, Eurocode, etc.) and for bridge assessment, mainly in fatigue, but also to estimate the extreme loads and load effects. WIM data were also used for traffic monitoring and statistics on road freight transport.

In the 90s, the first WIM standard (ASTM-1318) was published in North America, and the COST323 action provided European specifications of WIM as well as pan-European tests of WIM systems. The European research project WAVE (Weighing-in-motion Axles and Vehicles for Europe) and other initiatives delivered improved technologies and new methodologies of WIM.

In the early 2000s, the accuracy and reliability of WIM systems were significantly improved, and they were used more frequently for overload screening and pre-selection for road side weight enforcement controls (virtual weigh stations). The OIML R134 was published as an international standard of low speed WIM systems for legal applications like tolling by weight and direct weight enforcement. Most recently, the NMi WIM standard offers a basis for the introduction of high speed WIM systems for direct automatic enforcement and free flow tolling by weight.

In 2007 the International Society for Weigh-In-Motion was founded as a global association bringing together the stakeholders in WIM, to stimulate development in more advanced WIM technology and to promote the more widespread use of WIM system and data. For more information on the history of WIM please see the online ISWIM Library.