Electronic truck scales (US: truck scale; non-US: weighbridge; railroad scale for rail) are large, permanently mounted scale sets on a concrete foundation used to weigh entire vehicles and their contents by differencing empty and loaded weights, with 10-200 t weighing capacity, 2-3.5 m platform width, 6-24 m platform length, 8-12 mm tread plate, OIML III accuracy class, 150% rated-capacity safe overload, and scale-body operating temperature of -30 to +70 °C per the standard electronic truck scale specification [S1].
Standard accessories include load cell, indicator, junction box, signal cable, and lightning protector, and the operating power supply is 240/220/110 VAC at 50/60 Hz [S1]. A 40 ft container holds 2 units of 18 m scale, which sets a shipping baseline for procurement planning [S1]. For a baseline primer on the platform itself, see the truck scale reference.
Where a Truck Scale Earns Its Slot
Truck scales are specified in two distinct duty modes: trade-approved weighing for selling or charging by weight, and check-weighing of axle and gross vehicle weights to keep axle loads inside highway enforcement limits and avoid overloading fines [S1]. Typical deploying industries are mines, quarries, garbage dumps, recycling centres, bulk liquid and powder movement, household goods, and electrical equipment [S1]. A single-axle truck scale or axle weighing system can substitute for a full-size bridge where only axle-compliance checks are needed, and can be pit-mounted flush with the roadway or surface-mounted [S1].
Installation is one of the more under-estimated wins of a properly planned truck-scale project: with the foundation already cured, offloading the scale from the delivery vehicle and setting it on the foundation can be completed in roughly half a day, so most of the project critical path lives in civil works rather than the scale assembly itself [S8]. For fleets hauling into the same site, weighing the empty vehicle once and then re-taring per loaded pass keeps transaction time short and bulk-flow measurement accurate [S1].
Main Types and How They Compare on Decision Criteria
Three structural options dominate procurement, and the choice is largely a civil-works versus throughput trade. Pit-mounted (flush) scales put the weigh deck at road level, eliminating approach ramps and shortening truck cycle time at the cost of a deeper excavation and a more demanding drainage/water-management design. Surface-mounted (low-profile) scales use short approach ramps, cost less to install on green-field sites, but add a few seconds of ramp travel per crossing. Axle-only weighers sacrifice gross-vehicle accuracy for the lowest cost and the smallest footprint, fitting law-enforcement and quick-compliance roles rather than trade settlement. [S3]
On the four decision criteria that recur in spec reviews, the picture is consistent. Capacity: full-size electronic bridges span 10-200 t per the standard CSC-10 to CSC-200 platform matrix, while axle weighers are sized per axle and suited to a single-axle truck scale role [S1]. Accuracy: OIML III applies to the electronic bridge with a load-cell combined error of ±0.023% F.S. and a 2.0 ± 0.002 mV/V output sensitivity at Y = Emax/Vmin ratios of 15000 or 7500 depending on capacity class [S1]. Civil works: pit mounting needs deeper foundation and water management; surface mounting needs ramps; axle-only needs neither. Throughput: pit > surface > axle-only, driven by whether trucks have to climb onto a deck. Installation on a cured foundation can be roughly half a day for offload and set, so the structural choice mostly affects how much site work sits in front of that step [S8].
Engineering Specification Boundary Conditions
The load cell is the core component that converts weight into a measurable electrical signal, and its quality caps the entire scale, which is why the spec table reads like a sensor datasheet, not a piece of civil hardware [S1]. Key load-cell parameters for these bridges: OIML III accuracy, 3000 maximum load-cell intervals (nLC), 700 ± 7 Ω input and output resistance, ≥ 5000 MΩ insulation resistance at 50 V DC, recommended 4-12 V DC excitation (max 18 V DC), and compensated temperature -10 to +40 °C against an operating envelope of -35 to +65 °C and storage of -40 to +70 °C [S1]. Capacity steps are 10/20/25 and 30/40LE/40/50 t cells, with safe overload at 150% F.S. and destructive load at 300% F.S. [S1].
Mechanical envelope constraints matter as much as electrical ones. Platform width 2-3.5 m, platform length 6-24 m, tread plate 8-12 mm, U-shape beam structure, anti-rust and anti-corrosion painting, and indicator operating temperature of -10 to +40 °C define what will and will not survive a given site [S1]. Below the indicator's -10 °C floor the display electronics need a cabinet heater; above +40 °C the indicator cabinet needs sun shielding or air conditioning. Outside the scale body's -30 to +70 °C envelope, the platform and load-cell cabling begin to drift, and below -30 °C the brittleness of the protective paint and cable sheath is the more usual failure mode than the steel itself. These ranges are not marketing copy; they map directly onto real-world mining and northern logistics sites, where winter pre-calibration and summer thermal-shield retrofits are routine engineering work.
Failure Modes, Constraints, and Sourcing Watch-Items
The 150% rated safe-overload rating is a margin, not a license, and a recurring problem in the field is operators treating a 100 t scale as a 150 t scale, accelerating load-cell fatigue and the eventual combined-error drift above the OIML III ±0.023% F.S. envelope [S1]. Foundation settlement is the other slow killer: a 6-24 m deck is only as accurate as the concrete under it, which is why half-day mechanical installs still need weeks of curing, rebar, and pit drainage work in front of them [S8]. Pit mounting introduces water ingress at the junction box, so lightning protectors and properly glanded signal cables are non-optional accessories in any climate with freeze-thaw cycles [S1].
For procurement, the realistic constraints are total cost (foundation + scale + indicator + installation), lead time, and trade-approval status if the weighbridge is in commercial settlement. Trade-approved installations demand a sealed indicator and a verifiable OIML III chain of calibration, plus legal-for-trade paperwork that does not always ship with a low-cost overseas unit. For sites that handle bulk material around a quarry, comparing scale selection against the haul fleet's dump truck class is the easiest way to avoid over- or under-specifying capacity. Concrete delivery fleets running concrete mixer trucks and concrete pump trucks need OIML III-grade trade settlement because mix tickets are sold by weight, and any drift becomes a direct margin leak. Cold-storage or yard logistics running reach trucks and aerial work trucks are usually better served by axle-only systems, since the site rarely needs gross-vehicle trade settlement.
Installation Critical Path, Civil Works, and Acceptance
Half a day for offload and set is the optimistic number, conditional on the foundation already being in place, which is the variable that blows most project schedules [S8]. The realistic critical path is: site survey, foundation design to suit soil bearing capacity, excavation and rebar, pour and cure, scale delivery, offload and set, indicator and load-cell commissioning, OIML III verification, and trade-approval sealing if applicable. Each of those steps has a real lead time, and a foundation that is not engineered for the local water table will settle within the first two winters.
Acceptance testing should cover zero balance within ±1.5% F.S., combined error within ±0.023% F.S. across the capacity range, repeatability on a reference test weight, lightning-protection continuity on signal cables, and a documented calibration against the local mass standard [S1]. A useful next move is to request the load-cell certificate of calibration (Y, nLC, combined error) before purchase, and to verify that the indicator supports the local power supply (240/220/110 VAC, 50/60 Hz) and operating-temperature range of -10 to +40 °C for the given site [S1]. The two trackable signals to watch are the local weights-and-measures authority's re-verification cycle, which dictates legal-for-trade re-calibration intervals, and the foundation settlement log, which dictates when the scale should be re-levelled rather than re-calibrated. For related spec work on a different weighing-adjacent asset class, the industrial coating selection map covers trade-offs that pair with the anti-corrosion painting specified for the scale body, and the mining dump truck installation map lines up well with quarry-side truck scale deployment.