120 | TRAFFIC MANAGEMENT
The best of both worlds Haenni Instruments has developed a wheel-load scale that combines permanent and mobile weigh enforcement stations Words | Daniel Kneubuehl, Haenni Instruments, Switzerland
Mobile enforcement units remain popular as it is impossible for truckers to plan routes to bypass them
Why is it that mobile patrols are still used for weight enforcement when there are automated systems on the market that are much more sophisticated than a simple wheel-load scale? When talking about weight enforcement, the main focus is the reduction of the number of overloaded vehicles. The main factors for the effectiveness of any enforcement are the probability of detection and the amount of the fine to be paid. Permanent stations are very precise, but are also very likely to be bypassed by overloaded vehicles. Mobile weight enforcement is less efficient in weighing, but highly efficient in unsettling the drivers of overloaded vehicles. The bottom line is that weight enforcement with mobile scales is more effective. Aware of the importance of its mobile wheel-load scales for weight enforcement,
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Haenni Instruments wanted to improve what was already an excellent solution. What makes Haenni scales ideal for professional applications? This was the first question the in-house development team asked when they started designing a next-generation mobile wheel-load scale. “Besides offering easy handling, reliability and durability for many years, and being able to be used for legal metrology, two essential characteristics are needed: an extended temperature range and the thinnest weighing platform possible,” says Micha Kernen, Haenni project engineer.
Thinnest certifiable scales With a 17mm-high (0.67in) weighing platform, Haenni builds the thinnest certifiable wheel-load scales in the industry. “This has multiple advantages,” says Kernen. “Even the worst truck with overloading can
drive on it without ramps. To drive onto a 17mm-thick platform is equivalent to a gradient of 5%. Imagine if the platform was twice as high!” The low profile of the scale makes the leveling easier: the mats are small and the excavation is simple for semifixed use. Leveling is important in order to minimize measurement errors and it is mandatory in most countries. Even with this minimal platform height, Haenni scales fulfill the high standards of the International Organization of Legal Metrology (OIML). This is mandatory for weight enforcement and is a sign of quality that approves the reliability of the instrument. The temperature range of such a product has to be from -10°C up to +40°C (14°F to 104°F), according to OIML R76. “The scale must work in its specification in the cold winters of Canada, but also in the
