Granite Bollard Size and Price: Start with the Weight, Then How It Stands
Granite bollard size and price both come back to one number, the weight. A φ200×1000 piece is about 85 kg and a two-man lift with a carrying bar, since a polished cylinder has nothing to grip; at φ250 it reaches 133 kg and goes on a small hoist. Size is derived from what you are blocking and how much has to stand above ground, and the price from four items.
How is the size of a granite bollard decided?
The size of a granite bollard is not looked up in a table, you derive it from both ends. One end is what the bollard is meant to stop: a car bumper, or only a person while vehicles are kept out, and the two cases give different heights. The other end is how much of it should stand above the finished ground, because only the exposed part takes the hit and the buried part does nothing but sit gripped by soil. The ratio between the two is what makes it stand up to impact, and that ratio depends on the soil and on the vehicle, so it belongs to the contractor or the structural engineer rather than to the stone seller. Once the shape is fixed, work out the weight before anything else, because weight decides whether two men can carry a piece or a small hoist is needed, and how many pieces travel in a container.
How much does one bollard weigh, and how many fit in a container?
A bollard is cut from Sesame Grey (G602) block to the drawing, not built up from 30mm slabs. Granite is 2.7 t/m³, and a cylinder is π × radius² × height, so the weight of one piece is arithmetic you can do yourself. The figures below are converted from 28 tonnes of net stone and serve material take-off only; they are not a bookable load. The 28 tonnes come from our own record of 346 m² at 81 kg/m², the net weight of a 20ft container loaded with 30mm slabs, with no crates or dunnage counted in. A bollard is round, and packing and voids put weight on top, so take the allowances off as set out in our guide on why a container needs slack before you hand a figure to a forwarder. Take the height from 1000mm to 1200mm and the weight rises by a fifth, which takes a sixth off the number of pieces per container.
| Size (diameter × height) | Volume per piece | Weight per piece | Approx. pieces per 28 t net (packing not deducted) |
|---|---|---|---|
| φ150×1000 | 0.0177 m³ | about 48 kg | about 580 pieces |
| φ200×1000 | 0.0314 m³ | about 85 kg | about 329 pieces |
| φ250×1000 | 0.0491 m³ | about 133 kg | about 210 pieces |
Diameter 150, 200 or 250: what changes, and which do you pick?
Diameter changes three things at once. First, impact: bending capacity at the base rises with the cube of the diameter, so φ200 carries 2.4 times the bending of φ150 on only 1.8 times the weight. Work out the moment from the height at which the bumper or the cart handle actually strikes, then set the diameter. Second, weight: 85 kg is a two-man lift once you add a carrying bar, because a polished cylinder gives a hand nothing to grip; 133 kg goes on a small hoist, and the labour line moves with it. Third, footprint: the thicker the shaft, the more it blocks prams and wheelchairs, and this one goes into the access and accessibility checklist at handover, footpath openings above all. The choice is simple enough. At a footpath opening where you only keep vehicles out, go thinner. At a vehicle entrance that gets scraped in reverse, go thicker and add burial depth at the same time, because a bollard leans when the footing loosens first: a cracked shaft is a separate matter, and opening the footing tells the two apart. If you cannot decide, let the heaviest vehicle set the diameter.
Domed, chamfered or flat top: why does the machining cost differ so much?
Machining cost follows the number of operations and the waste, not the weight of the stone. A flat top is one cut and the piece leaves the saw. A chamfer is a cut plus a ground bevel, one more set-up and one more pass. A dome has to be turned or profiled, which is more steps than either, and the shoulder is where it chips; a chipped dome is downgraded or scrapped, and that loss ends up in the rate. There is a point that gets missed: a dome or a chamfer is not only about looks, it removes the sharp corner, so there is one less injury point when someone walks into it or sits on it, and on plazas and at school gates the handover list carries a separate sharp-corner item, raised by the inspector and absent from the owner's purchase order. A reflective-band groove or a chain hole is secondary machining. Groove width, depth and distance from the top have to be fixed before the order; changing them afterwards means starting again.
How do you fix a bollard so it does not fall over?
Three ways of setting one, each doing a single job. Direct burial is the usual way: the soil grips it, the buried depth has to suit the exposed height, and loose ground means going deeper or adding a concrete collar. The contractor does that, and the factory only cuts the piece to the total length you ask for. Drilling the base for a pin or a steel rod suits anything that has to come out again, and hole positions, diameter and depth must be settled before the order, since drilling on site chips the edge easily, with no jig to hold the piece and no control over the feed, and a chipped hole cannot be filled, only downgraded or scrapped whole; the factory drills and the buyer supplies the hole layout. The third way is to stand the piece on its own weight as movable segregation; that only guides people and does not stop a vehicle: go back to the table and take the moments. A φ200 piece resists tipping with 85 × 9.8 × 0.1 ≈ 83 N·m, assume a person pushing 300 N at 0.9 m, and that is 270 N·m on the same piece, so all three sizes go over. To stop a car, bury it or anchor it through the base. Keep the responsibilities on separate sheets, burial and concrete on the contractor's, drilling on the factory's, the hole drawing on the buyer's. Put them on one sheet and the factory waits for a drawing while the site waits for stone.
Quoting by the piece: what must the order say?
Quoting by the piece only works if the piece is defined, and four items decide whether two quotes can be compared at all. One, diameter × height, stating whether that height includes the allowance for the top profile, since a dome needs stock left for turning. Two, surface finish: polished, flamed or bush-hammered. A bollard is not a walking surface, so polish has nothing to do with slip: polished is chosen because it hoses down easily and reads bright, and the price is that knocks and tyre marks show up on it more than on any other finish, so at a lane edge where abrasion is expected, take flamed or bush-hammered. Three, fixing: no holes, how many holes, what diameter, steel rod included or not. Four, quantity and delivery basis: ex works or landed, one shipment or several. Settle those four, then talk about money, and ask for the quote broken down into stone, machining, packing and freight; a single total cannot be compared. One last step: do not open with a full container. Run 10 to 20 pieces to the site and set them once. What you are testing is whether they stand steady, whether the colour shift is acceptable, and how many men it takes to move one, and none of the three shows up in a photo or a quotation. What we keep in stock is 30mm Sesame Grey (G602) polished slab, 100 m² minimum, five days to ship, 346 m² to a 20ft container; that is the slab line's figure. Bollards are a special shape, cut from G602 block to order and not run on the slab line, so the five days does not apply to them: the lead time is quoted separately once diameter, height, top profile and hole drawing are confirmed. Guangxi Shicai Stone Industry Co., Ltd. splits the order the same way.