Capacity is the first number a buyer picks and the one they get wrong most often. Some undersize to save two lakh, then watch load cells drift within eighteen months. Others buy a 100-tonne deck for a yard that never sees a vehicle above 35 tonnes, and lose weighing resolution on every small load. The right answer comes from three inputs: your heaviest legal vehicle, your longest vehicle, and your concentrated axle load. This guide works through all three, maps them to the 40, 60 and 100 tonne classes, and shows what you cannot change after installation.
Capacity and Length Are Two Different Decisions
Buyers say “60 tonne weighbridge” and mean one thing. Manufacturers hear two.
- Capacity is how much total weight the deck and load cells carry safely. It is set by load cell rating and structural design.
- Deck length is how much vehicle fits on the platform at once. A vehicle must sit fully on the deck for a single-draft weighment.
You can have a 60-tonne capacity on a 12-metre deck or on an 18-metre deck. The capacity is the same. What fits on it is not. Decide both, separately, before you ask for a price.
Start With Your Heaviest Legal Vehicle
Under India’s axle-load norms, permissible gross vehicle weight climbs sharply with axle count. Approximate working figures:
- 2-axle rigid truck: around 16 tonnes GVW
- 3-axle rigid: around 28 tonnes
- 4-axle rigid: around 36 tonnes
- 5 and 6-axle tractor-trailer: roughly 44 to 55 tonnes gross combination weight
Check the RC of the heaviest vehicle that will actually enter your gate, including customer trucks you do not control. Do not average. The deck sees the maximum, not the mean.
The Headroom Rule
Add 25 to 30 percent above your heaviest expected vehicle. Two reasons:
- Overloaded vehicles arrive at your gate. That is often the whole point of owning a weighbridge.
- Dynamic load during drive-on briefly exceeds static weight, especially with a hard braking driver.
A yard whose heaviest truck is 45 tonnes needs 60 tonnes of capacity, not 50.
But Do Not Overshoot
Resolution is division size. A 100-tonne weighbridge with 10,000 divisions reads in 10 kg steps. Weighing a 6-tonne pickup on it gives you a usable but coarse reading. If most of your traffic is light and only a few vehicles are heavy, that trade-off deserves a conversation, not a default.
The Spec That Actually Breaks Decks: Concentrated Load
Total capacity is not what fails first. Concentrated load capacity is.
A single axle group parked mid-span applies far more localised stress than the same tonnage spread across a full trailer. Multi-axle trailers with tight axle spacing, or short dumpers with rear-heavy loads, punish decks that were specified only on total capacity.
Ask every supplier for the concentrated load rating in tonnes per axle group, and check it against your heaviest single axle group. If the answer is vague, that is your answer.
The 40 Tonne Class
Typical deck: 9 to 12 metres Fits: 2-axle and 3-axle rigid trucks, tippers, small tankers
Who It Suits
- Small manufacturing units receiving raw material by rigid truck
- Grain and agri procurement centres
- Municipal waste and small aggregate yards
- Warehousing sites with local distribution fleets
The Limit to Watch
A 12-metre deck does not fit a full tractor-trailer. Multi-axle vehicles must be weighed axle by axle, which is slower and legally restricted for trade weighing in many cases. If even 10 percent of your traffic is trailers, this class is the wrong choice.
The 60 Tonne Class
Typical deck: 16 to 18 metres Fits: almost every commercial vehicle on Indian highways, including most 6-axle trailers
Who It Suits
- General manufacturing and engineering plants
- Logistics and transport yards
- Cement, steel, and building material dealers
- Food processing and cold chain hubs
- Most factories with mixed inbound and outbound traffic
This is the default for good reason. It covers the legal maximum for standard trailers with headroom, and an 18-metre deck accommodates full vehicle length in one draft.
Why Most Buyers Should Start Here
The equipment cost gap between 40 and 60 tonnes is smaller than the operational gap. You are buying a heavier deck and higher-rated load cells, not a different category of machine. Buyers who choose 40 to save money often replace within five years.
The 100 Tonne Class
Typical deck: 18 to 24 metres Fits: long trailers, low-bed carriers, ODC movements, multiple vehicle configurations
Who It Suits
- Mining and quarrying operations
- Ports, container yards, and freight terminals
- Steel plants and heavy fabrication units
- Sugar mills and large agri processing during peak season
- Sites weighing over-dimensional or project cargo
What You Actually Gain
- Structural headroom for continuous heavy-duty cycling, which extends deck life
- Ability to weigh two shorter vehicles in sequence on a long deck
- Tolerance for concentrated loads from tight axle groups
What You Pay For
More steel, more load cells, longer foundation, and a longer approach. The equipment cost rise over 60 tonnes is moderate. The civil cost rise is not.
Daily Volume Changes the Answer Too
Capacity is a structural question. Volume is a fatigue question.
- Under 40 vehicles a day: standard specification serves well
- 40 to 100 vehicles a day: ask for heavier deck sections and a higher IP rating on load cells
- Over 100 vehicles a day: specify one class above your load requirement, and treat automation as part of the base scope
Steel does not care about a single heavy truck. It cares about a hundred thousand cycles.
What You Can Upgrade Later, and What You Cannot
Can be upgraded
- Indicator and software
- Cameras, RFID, barriers
- Remote display and printers
- Load cells, to a different type of the same rating
Cannot be upgraded
- Deck length
- Foundation length and depth
- Structural steel section sizes
- Approach paving geometry
The permanent list is all civil and structural. That is where to spend your caution, and where headroom is worth paying for.
A Three-Step Sizing Method
- Find your maximum. Note the heaviest GVW and the longest wheelbase that will enter your site, including third-party vehicles.
- Add headroom. Multiply the weight by 1.3 and round up to the next standard capacity. Add 1.5 metres to the longest vehicle length for deck length.
- Check concentrated load. Take your heaviest single axle group and confirm the supplier’s concentrated load rating exceeds it with margin.
Run those three steps and the class picks itself.
Match the Capacity to the Material, Not Just the Truck
Two yards can run identical trucks and still need different specifications, because material behaviour changes what the deck experiences.
- Bulk aggregate, coal, ore. Loads settle unevenly and shift during drive-on. Specify higher concentrated load capacity and a heavier deck section.
- Liquid tankers. The load sloshes, so the reading takes longer to stabilise. Prioritise a good indicator with proper stability filtering, and expect a slightly longer cycle time.
- Bagged goods and palletised cargo. Loads are distributed evenly and predictably. Standard specification serves well.
- Scrap and mixed loads. Highly irregular distribution with sharp point loads. Deck plate thickness matters more here than total capacity.
- Cement and fly ash. Fine dust penetrates everything. Specify a higher IP rating on load cells and sealed junction boxes regardless of capacity class.
The Practical Takeaway
Two sites weighing 45-tonne trucks may need different weighbridges. Tell your supplier what is inside the truck, not just how heavy it is. That single detail changes deck design more often than capacity does.
FAQs
Can I weigh a 70-tonne truck on a 60-tonne weighbridge once? Physically, most decks tolerate a modest single overload without visible damage. Repeatedly, no. Overload causes permanent load cell drift long before the steel shows any sign, and drift is invisible until a calibration fails.
What deck length do I need for a full trailer? Most 6-axle tractor-trailers need 16 to 18 metres to sit fully on the platform. Measure your longest actual vehicle rather than trusting a class average, since body lengths vary widely.
Is axle weighing an alternative to a longer deck? Axle weighing works for screening and internal control, but summing axle weights introduces error and is restricted for trade use in many situations. If you issue commercial weight slips, weigh in a single draft.
Does higher capacity mean lower accuracy? Not accuracy, resolution. A larger capacity generally means a larger division size, so light loads are read in coarser steps. Match the class to your traffic rather than buying the biggest available.
Should I size for future expansion? Size the civil work and deck length for ten years, since those cannot be changed. Electronics and automation can be added at any time, so there is no benefit in over-buying them upfront.
Conclusion
Pick your capacity from your heaviest vehicle plus 30 percent, pick your deck length from your longest vehicle plus a metre and a half, and confirm concentrated load before you sign. Get those three right and the weighbridge will outlast the trucks it weighs.
Get Your Capacity Checked Against Your Actual Traffic
Matrix Weighbridge supplies 40, 60, 100 tonne and higher-capacity weighbridges, with deck length, structural sections, and concentrated load ratings stated clearly in every quotation.
Send us your vehicle list, heaviest GVW, and daily truck count. We will recommend a capacity and deck length, and tell you plainly if a smaller one will do the job.