Access, crane and unloading: what to check before planting

Before reserving a mature tree, you need to confirm that the lorry and the crane can reach the site and set the specimen in its intended position.

The width of the gate is only part of it. Bends, gradient, the bearing capacity of the paving, outriggers, cables and the reach to the planting hole can greatly reduce the size that is possible.

The assessment should happen before work starts and, ideally, before the site sequence is fixed.

Measure the usable width, not just the distance between walls. Gates, hinges, piers, vegetation and signage can all take space away.

Headroom includes branches, cables, balconies, eaves and light fittings. A tied-in crown still takes up volume and may not pass through an opening that looks wide enough for the trunk.

The turning circle is often more limiting than the width of the road. A long lorry needs room to line up and to get out again.

The combined weight of the vehicle, the crane and the tree can damage paving or make unconsolidated ground give way.

Steep ramps affect traction and stability. Wet surfaces increase the risk.

The team checks what the surface is made of and does not assume that a residential driveway will take heavy equipment just because it takes cars.

Load-spreading plates, temporary reinforcement or a different unloading position may be needed.

The crane needs to extend its outriggers onto a firm base. Walls, planting beds, inspection chambers and banks can prevent the set-up required.

The position chosen must allow the crane to work without exceeding its capacity at that reach. The further away the load is, the less weight the machine can lift.

The crane’s load chart is checked by a competent person against the estimated weight of the tree.

Between the vehicle and the planting hole there is a three-dimensional volume.

The tree may have to pass over walls, roofs or vegetation. A tied-in crown is not rigid and can swing. Nor can the rootball be turned freely without controlling the centre of gravity.

Power lines require safety clearances and can rule out the operation altogether.

A two-dimensional site plan does not show all these obstacles. The site visit should look at heights and movements.

The hole needs to be dug, drained and at a confirmed level before the tree arrives.

The ground beside the position must allow the load to be brought in. Backfill soil, stakes and anchoring materials are kept within reach without blocking the crane.

It is not desirable to set the tree down to one side while the team finishes the preparation. Large rootballs lose moisture, and lifts have to be repeated.

Mature trees are not a finish that always goes in last.

Walls, railings, pergolas, façades, paving and furniture can close off the access. On many projects, the large trees are placed before these stages are completed and protected afterwards.

The programme should mark this dependency and coordinate responsibilities between contractors.

The area is cordoned off and one person coordinates communication with the operator.

The way the tree is slung follows the form of the specimen. Younger trees can take padded slings on the trunk; multi-stems and shrubs can be supported by the rootball with a second stabilising point. With the largest sizes, the main load is carried at the rootball and the trunk helps to control rotation.

While the crane still holds part of the weight, the level, the orientation and the intended lean are confirmed. Nobody stands under the load or between the rootball and a fixed structure.

Strong wind increases the movement of the crown and makes the load hard to control.

Rain can reduce the stability of the ground and of the outriggers. In intense heat, the rootball and the crown dry out during the wait.

The operation is postponed when conditions go beyond safe limits, even if the transport is already booked.

The visit records measurements, photographs, levels, the route and the position of the equipment. The design provides the species, form, rootball size and orientation.

With this information, a compatible tree size and machine can be chosen. Without it, the decision rests on an estimate that will only be tested once the tree is already on its way.

You can choose a smaller tree, a form with a more compact crown or a production system with less weight.

Another solution is to bring planting forward to a stage when the access is still open.

On some sites, a crane with a longer reach solves the distance, but it increases the space and capacity required.

Access is not a problem separate from the design. It is part of selecting the tree and should be considered from the outset.

• How a large tree is transported
• Planning external works
• How to choose a specimen at the nursery

1. Diaplant’s procedures for site visits, unloading and planting.
2. Safety rules and load charts specific to the lifting equipment.
3. European Arboricultural Standards. European Tree Planting Standard.