Plan the route around the longest and heaviest unit in the mix, not the average one. That single decision fixes the portal width, the aisle width, the corner radii and the lift height. Everything else — storage layout, truck position, drainage — is arranged so that this worst-case unit can travel from the casting bed to the trailer without reversing into a blind corner.
Precast yards are usually laid out before the lifting equipment is chosen. The beds go where the concrete can be poured, the storage rows go where there is space, and the loading bay goes where the trucks can reach. The carrier then arrives and has to work inside a layout designed without it.
That sequence produces the same three problems on most sites: an aisle too narrow at one corner, a lift height that stops one stack short, and a drainage trench on the shortest route. All three are cheap to fix on paper and expensive to fix in concrete.
1. Start with the product mix
Before drawing anything, list the units the yard will handle and mark three of them:
- The longest unit. It sets the aisle width at corners and the swept path of the load, not just the machine.
- The heaviest unit. It sets the capacity at load centre, the wheel count and the wheel loads that the slab has to carry.
- The most frequent unit. It sets the cycle that the yard will actually run, and therefore the travel distance that matters.
These are often three different products. A yard that stores 12 m panels every day and a 30 m bridge beam twice a month still has to move the beam — so the route is designed for the beam, while the cycle time is designed for the panels.
If the mix is still growing, say so. Designing the frame for a load that is 20% heavier than today's heaviest is a different decision from designing the aisle for it, and the two should be made deliberately rather than by accident.
2. The four stages the route must connect
Casting bed
The pick-up point. Lifting inserts, edge clearance and the demoulding strength all affect when the unit can be moved.
Curing area
Where the unit waits. Usually the tightest part of the yard, and the one most often filled with temporary storage.
Storage rows
Where the unit sits until it is called off. Access has to survive a full yard, not an empty one.
Loading bay
Where the unit meets the trailer. Trailer deck height, approach angle and securing time all belong here.
Draw the route as one continuous line through all four, in both directions. The return trip is not a formality: an empty carrier still needs the same aisle, and a route that only works when laden is a route that will be driven the wrong way round under time pressure.
3. Aisle width, portal width and tail swing
Three different widths get confused in early layout drawings.
- Portal width is the clear opening inside the machine, where the load sits. Our published load-area width is 3,200 mm on the 35 t model and 3,700 mm on the 60 t and 80 t models.
- Overall width is the outside of the machine. The 35 t configuration is 5,100 mm wide; the 60 t and 80 t are 5,950 mm.
- Route width is the clear space the machine and its load need to pass, turn and stop. It is always wider than the overall width.
Then add the part that drawings usually miss: the load overhangs. A 30 m beam carried centrally extends far beyond the machine in both directions, and its ends sweep a much larger arc than the machine at every corner. The correct check is the swept path of the load, drawn at the tightest radius the yard will actually use.
This is where the six steering modes earn their place. Front-wheel and Ackermann steering handle normal travel. Crab steering moves the machine sideways without changing its heading, which is useful for aligning with a storage row. Carousel and four-way modes let the machine rotate or travel in either axis in a confined area. In an existing yard, a different steering mode is often cheaper than moving a wall.
Turning radius follows the wheelbase: our 35 t model turns in 7,000 mm, the 60 t in 10,000 mm and the 80 t in 12,000 mm. If a corner in the yard cannot accommodate the larger radius, the choice is a shorter machine, a different steering mode, or a new corner — and it is worth knowing which before the order.
4. Ground, joints and drainage
A loaded straddle carrier puts a high point load on a small contact area, and precast yards are often the least prepared surfaces for it. Four items matter:
- Maximum wheel load, not average pressure. A long unit carried towards the front of the portal shifts weight onto the front axle group. The slab has to be checked against that case, not against the machine's total weight divided by four.
- Joints and edges. Slabs fail at joints and free edges more often than in the middle. Route the machine across joints at a sensible angle and keep the path away from unsupported edges.
- Drainage and services. Trenches, catchpits and duct banks are voids under a wheel. Either keep the route clear of them or design the crossing as a structural element.
- Slope. The 35–80 t configurations are rated at 3% gradeability laden and 5% unladen. A yard that drains towards a ramp may be fine empty and marginal when carrying a beam.
Precast yards also tend to be semi-rough: sand, slurry, offcuts and cable runs. That affects tyre choice as much as the slab does, and it is worth showing us photographs of the route in normal working condition rather than on a clean day.
5. Storage and stacking
Most precast units are stored one high, on timber or concrete cribbing placed under the designed bearing points — not under the lifting inserts. That is a lifting-geometry rule as much as a structural one: a unit supported away from its bearing points carries loads the designer did not intend.
Stacking two high is possible, but it is a decision about the product and the frame, not a way to save space by default:
- The lower unit must be designed and cribbed to carry the upper one.
- The carrier needs lift height for both units plus the cribbing, plus clearance to place the upper unit without touching the lower one.
- Access to the lower unit disappears while it is covered, so the storage plan has to match the call-off sequence.
For long units, the storage row itself becomes part of the route: the carrier approaches from the end, lifts, and reverses out along the same line. Rows that are too close together turn a simple retrieval into a multi-move manoeuvre.
6. Loading the trailer
The loading bay is where the yard meets the road, and it is usually the tightest constraint in the plan.
- Side loading or end loading. A trailer that is approached from the side needs clear space along its full length; an end-loaded trailer needs a longer approach. Both need the carrier to place the unit without the trailer moving.
- Deck height and lift height. Placing a unit on a trailer deck is a different lift height from placing it on the ground. Check the highest trailer you will load, not the average one.
- Trailer position and slope. A trailer parked across a drainage fall puts the unit on a slope at the moment of setting down. Mark the bay and keep it level.
- Securing time. The carrier is occupied until the load is secured. A bay designed without space for the securing operation adds minutes to every dispatch.
If the yard loads both flatbeds and low-loaders, draw both cases. The lift height and the approach that work for one may not work for the other.
7. Layout checklist
| Item | Why it matters | Who provides it |
|---|---|---|
| Longest and heaviest unit | Sets portal width, aisle width and capacity | Yard / engineering |
| Plan view with swept paths | Proves the route works at every corner | Yard, reviewed by us |
| Door, roof and conveyor clearances | Height under load is the usual late surprise | Site survey |
| Slab drawing and joint layout | Wheel loads are checked against the real slab | Structural engineer |
| Buried services and drains | Voids under wheels are failure points | Site drawings |
| Storage and call-off sequence | Access has to survive a full yard | Production planning |
| Trailer types and bay levels | Lift height and securing space at dispatch | Logistics |
Send the plan view and the slab drawing and we will return a dimensional proposal with the route marked, the turning envelope checked and the wheel loads for your engineer. The precast concrete page covers the lifting frames and attachments that go with it, and the selection guide explains how the eight machine numbers are set.
Yard planning FAQ
Can a straddle carrier work in an existing yard with narrow aisles?
Often yes, with a shorter machine, a narrower portal or a steering mode that lets the machine rotate in place. The limit is the swept path of the longest load, which no steering mode can shrink. That has to be measured before the machine is ordered.
How wide should the aisle be?
Wider than the overall machine width, plus clearance for the load overhang and for the operator's sight line at corners. The reliable method is to draw the swept path at the tightest radius rather than apply a fixed allowance.
Can the carrier travel on the casting bed slab?
Only if that slab has been checked for the wheel loads. Beds are often designed for the weight of concrete and formwork, not for a loaded carrier crossing them, and the joints are in the wrong places for a wheel path.
Do we need a reinforced route?
Not always. A route that avoids buried services, crosses joints squarely and stays away from free edges may need nothing more than a surface repair. The wheel load calculation tells your engineer where reinforcement is actually required.
Can the machine load directly onto a truck from the casting bed?
Sometimes, and it shortens the cycle considerably. It requires the truck to reach the bed without blocking the yard, and the lift height and approach to work at that position. Worth designing in if the dispatch pattern is regular.