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3 - Site Conditions, Construction, and Foundation A truck scale is a large construction site requiring up to 200 ft (60m) in length and 20 ft (6m) in width of yard space, not including the scale house. Positioning and placement of the truck scale for each site is critical to the efficiency and safety of the operation. Below are the site specific considerations for new truck scale installations.
4 - Weighbridge Selection and Options
A truck scale is a long-term capital asset purchase. Consider trade-offs in asset life, durability, performance, and price.
Design Requirements and Considerations
Site-Specific Considerations
Scale Capacity / Scale Accuracy All truck scales are certified by the local Weights and Measures authority. This authority defines the capacity and accuracy limitations for legal-for-trade applications. Scale division size is based on load cell weighing sensor performance and W&M certification testing. Typical truck scales have a standard division size of 20 lb (10 kg). Higher performance systems can be certified to 10 lb (5 kg) divisions for improved accuracies on smaller vehicles and higher value material. Durability / Scale Life Factors • Structural design life (typically 20+ years) • Estimated load cycles per year (# of truck loads per year) • Safety factor of designed loads (axle group loading, typically 1.5X to 2.5X legal over-the-road) • Verified life cycle testing of designs (typically 2M load cycles at design load)
Truck scales can be installed either flush to the drive surface (in-ground) or raised above ground. There are advantages and trade-offs to both types.
A pit-style scale is placed in an excavated foundation In-ground considerations: • Requires less yard space • Allows cross traffic • More expensive foundation • Susceptible to material build- up in the pit • Requires active drainage system • Maintenance in the pit re- quires confined space safety considerations
Some sites find an open-sid- ed scale easy to clean Above-ground considerations: • Requires more yard space • Less expensive foundation • Less susceptible to material build-up • Raised driving surface can create driving and driver safety issues • Better maintenance and service access
Suitable scale placement can increase the efficiency of a site
Concentrated Load Capacity (CLC) Sectional load test during W&M certification. This is not a measure of design durability.
Other site considerations: • Turning radius for truck alignment
Load Cell / Weighing System Selecting the right load cell system is critical for the truck scale buying process. Typically, the load cell system is the truck scale component that is most susceptible to environmental damage and critical for accurate weighing.
• Hazardous area classification • Truck traffic flow and queuing • Driver and scale house oper- ator safety
Design requirements to consider: • No junction box or load cell termination enclosure at the weighbridge • No legacy strain-gauge analog load cells (50+ year old sensor technology) • Digital, smart sensor network only
Environmental Protection The truck scale is typically positioned outside in the environment and thus can be affected by water, flooding, extreme temperature changes, lightning strikes, rodents, and material build-up.
Critical environmental criteria to consider: • IP68 (high pressure washdown) / IP69K (submersible) rated load cells • Stainless steel hermetically sealed load cells
• 3rd party lightning tested and certified electrical system • Stainless steel shrouded cables to protect against rodents
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