The Factory From Above: Site and Line Layout
From the air you see less of the plant and more of the plan. Road geometry, dock orientation, the gap between two halls, the empty lot on one side — all of it fixed on a site drawing long before the first machine arrives. Those lines decide how often a trailer has to reverse, whether inbound and outbound fight over a single gate, and whether a second building is still possible ten years out. A drone pass takes forty seconds; the decisions underneath it hold for a decade. What follows reads the layout rather than touring the floor.
01One-Way Flow: Separate Gates at Opposite Ends
Material enters at one end and finished goods leave at the other, with nothing turning back. Separate the two streams and the yard needs no passing lane and no wide apron: a 17.5 m trailer follows a single arc from gate to dock. Run both through one gate and you save a guard post and a weighbridge, then pay for it in a queue every morning of the year.
The second gain is that the finished-goods area never doubles as a corridor. A forklift passing close to packed cases is how cosmetic rejects happen, and one brushed pallet is enough. Foot traffic belongs against the outer wall, 1.2 to 1.5 m wide, behind a kerb or hedge. On any site plan, count the crossings first: each one is a spot that needs a person watching it.
02Docks: A 1.1–1.3 m Step and a 4–6 m Canopy
Dock height runs 1.1 to 1.3 m to meet the floor of a box truck or a 40HQ. Ten centimetres off and every forklift entry needs a plate, hundreds of times a day. Depth is 3 to 4 m so a truck can turn and stage a pallet; the opening clears 3 m for high lifting. A site with no dock and tail-lift unloading adds 1 to 2 hours per container.
The canopy projects 4 to 6 m, and it shelters cargo rather than people. Cases sit exposed at an open door for fifteen minutes, and one shower is enough to ruin a batch. Its underside should clear a trailer roof by 0.5 m or more, or a reversing trailer will find it. Fall the apron away at 1% to 2%: steeper and forklifts slip, flatter and water stands.
03Turning Radius 12–18 m: The Empty Corner Is Working
A 17.5 m trailer needs 12 to 18 m to turn, depending on wheelbase and kingpin position. Main aisles run 6 to 9 m, with corners either chamfered or curved, or the driver reverses at the same spot every day. A turning apron wants roughly 25 m across. Those corners look like waste until they become parking, and the blockage appears the same week.
Insufficient radius leaves tyre marks. Look at the inside of a bend: dark arcs in the asphalt mean the trailer is scrubbing, which wears sidewalls and tears the surface. Two repairs exist — set the kerb back 2 to 3 m into a chamfer, or make the road one-way. The first is cheap; the second rewrites the site's traffic order and is usually the correct answer.
04Fire Lanes and Building Gaps: The Lines You Cannot Stack On
Fire lanes stay clear at 4 m minimum, widened at bends for an appliance, with nothing overhead and pavement rated for the load. This is the first line to be borrowed: a waiting truck, empty pallets, goods awaiting inspection. Once the paint vanishes under a pallet, an audit becomes a finding. From above, a continuous lane says more than any facade.
Eight to 15 m between halls covers fire separation, but also pipe racks, trenches, hydrants and daylight. Squeeze it to 6 m and there is no working face for maintenance, so one new cable means a shutdown and a trench. That gap is also the expansion joint: a hall built tight against the old one turns the space into either a link corridor or a dead pocket, decided by how much was left.
05Reserving 20–30% of the Land on the Outbound Side
Land is usually held at 20% to 30% of the built footprint, on the dispatch side rather than the receiving side. New capacity mostly ships out, so a store near the dock saves a handling move; put the hall at the inbound end and the material route is severed. Nothing permanent goes on reserved ground — trailers, canopies and planting all move later.
Test a reservation with one measurement: clearance from the proposed wall to the edge of the main aisle. Under 9 m and the building should not go there, because turning radius and fire lane get squeezed at the same corner. The second test is whether flow stays one-way afterwards; if trucks must cross the production floor, the project is a rebuild, not an extension.
| Trailer turning radius | 12–18 m |
|---|---|
| Main site aisle | 6–9 m |
| Fire lane clear width | ≥4 m |
| Gap between buildings | 8–15 m |
| Dock face height | 1.1–1.3 m |
| Canopy projection | 4–6 m |
| Turning apron diameter | about 25 m |
| Land held for expansion | 20–30% |
FAQ
Why keep inbound and outbound gates apart?
Shared gates put loaded and empty trucks on the same stretch of road, which forces passing lanes and a turning area inside the fence, plus a morning queue. Split them and a trailer follows one arc while the finished-goods area stops being a corridor. A guard post and a weighbridge are cheap next to daily waiting.
Why is dock height set at 1.1–1.3 m?
That matches the floor of a box truck or a 40HQ. Ten centimetres low and every forklift entry needs a plate, hundreds of times daily; too high and the seal leaks in rain. Depth of 3 to 4 m is what leaves room to turn and to stage a pallet at the door.
Is unused yard space a waste?
It is the buffer for vehicle movement. Without enough radius a driver reverses at the same corner daily, damaging tyres and pavement. Convert that ground to parking and the blockage shows up immediately. The area worth trimming is building footprint, not the turning circle.
What is the commonest expansion mistake?
Building tight against the existing hall, closing the gap below 6 m. That removes the maintenance face, the fire lane and the turning radius at once, so one new cable later needs a shutdown and a trench. The test is simple: under 9 m from the proposed wall to the aisle edge, build somewhere else.