Increased pressure to identify overloaded commercial vehicles on our nation’s highways along with advancements in technology and the move to institute legal metrology performance standards will result in the increased use of in-motion vehicle or WIM scales. Until recently, the vast majority of WIM scales were used in monitoring commercial traffic without impeding traffic flow. Other industries are now taking note of the advantages offered by this technology and are beginning to use WIM scales in different applications.
WIM scales, like Cardinal Scale’s QWIM series, are commonly used to identify over weight commercial vehicles on mainline state and interstate highways for enforcement static weighing as well as sorting vehicles entering highway weigh stations returning those with legal weights to the interstate highway. These scales are beginning to find use in other applications. For example, this type of WIM scale is used in mines to weigh ore trucks on their way to the crusher. Still other applications include weighing trucks entering and leaving sea ports. WIM scales are also being used to improve our safety. For instance, they can be used to track the weights of vehicles entering and leaving parking garages to determine the total load on the parking structure. They’re also used to warn vehicles approaching a curve or a bridge that their speed or weight is unsafe.
Some of the reasons that scales like the QWIM series find use in these applications is the fact that they provide good weighing accuracy while being unaffected by changes in pavement temperature. The quartz sensors are ground flush with the surrounding pavement making damage from a passing snowplow highly unlikely. Further still, unlike those WIM scales employing some type of strain gauge technology, the quartz sensors are highly resistant to damage from moisture and voltage surges. This sensor technology coupled with Cardinal’s new CVW Series In-Motion Scale Controller offers previously unavailable features and performance in a compact package. This new controller is fully contained on a single multi-layer printed circuit board and uses a one hundred percent SMD design. Included on the board is a high-speed ARM processor with a core speed of 100 MHz, a 4-channel 14-bit A/D converter, 512 Kb program memory and 256 Kb of RAM. Other features include a USB port for field upgrades, a micro SD card slot for mass storage of data, Ethernet, and multiple serial ports. Sensor inputs along with multiple outputs increase its flexibility. An embedded web page makes setup and configuration easy and extended diagnostics allows thorough interrogation of the controller. The controller is equipped to produce not only axle weights but left and right side weights and classification for vehicles with up to 13 axles. Additional option cards can be added to the CVW controller to produce a system exactly right for most any application.
The world of legal metrology has also taken note of the increased use of WIM vehicle scales. Most recently a workgroup was formed under the guidance of the Federal Highway Administration (FHWA) to develop standards for the performance of WIM scales used for the identification of over-weight commercial vehicles. After several years of work, the new code is ready for use. The adoption of this code will be voted on at the one hundredth meeting of the National Conference on Weights and Measures (NCWM) at their July meeting in Philadelphia. If adopted, this code will become part of the 2016 edition of the Handbook 44 published by the National Institute of Standards and Technology (NIST). You can view the proposed WIM code at www.ncwm.net.
For noncommercial applications where speed and volume are of the essence, the use of WIM scales for vehicles will only grow pushed along by improvements in sensor and instrumentation technology. It is exciting to think what the future may hold.