A tower crane is chosen not by the maximum capacity in its name but by a few points on the site plan: what has to be lifted, where, and how high. Here is a practical order in which to settle those questions.
1. The heaviest lift and its radius
List the heavy lifts: concrete skips, rebar bundles, formwork, precast elements, rooftop plant. For each, note the weight including rigging and the distance from the crane's axis to where it is picked or set down. A tower crane's maximum capacity is available only close to the tower; further out along the jib it drops.
2. Load at the jib tip
The second key figure on the data sheet is the tip load — it limits work in the far corners of the site. For example, according to the Kranovshik catalog the Liebherr 110 EC-B 6 has a 6 t maximum and 1.5 t at 55 m, while the Liebherr 280 EC-H 12 has 12 t and 2.5 t at 75 m. If the farthest heavy lift does not pass at the tip, you need a bigger crane or a second crane position.
3. Coverage
Draw a circle on the plan with a radius equal to the jib length. All pick and set-down points must fall inside: storage areas, truck access, the whole building footprint. Check the tail — the counter-jib sweeps a circle too and must not hit neighbouring buildings or other cranes.
4. Hook height
The required height is the highest lift level plus the height of the load and slings plus clearance over obstacles. For the building under construction, work from the top level including parapets, plant rooms and rooftop equipment.
5. Freestanding height and tie-ins
Every crane has a freestanding height. If the building is taller, the tower is extended and tied to the structure. Tie locations, embedded plates and loads on the structure are agreed with the structural engineer in advance.
6. Crane type
- Classic hammerhead with a tower head — usually cheaper to rent and typically allows a greater freestanding height.
- Flat-top — convenient when several cranes on one site overlap at different heights; easier to erect.
- Luffing jib — the jib changes its angle instead of using a trolley. Needed on tight city sites where the jib must not oversail neighbouring plots, and under airspace restrictions.
- Self-erecting — for low-rise work: it arrives on site and unfolds itself within hours.
7. Site constraints
Neighbouring buildings and the right to oversail them, power lines, roads and footpaths, nearby airfields, other cranes — all of these decide where the crane can stand, how long its jib can be and whether an anti-collision system is needed.
8. Foundation and power
The crane needs a foundation or rail track designed for the manufacturer's loads and the actual ground. Most tower cranes are electric: check that the site supply is sufficient, or plan for a generator.
9. Erection and dismantling
Erection needs access for the trucks carrying sections and a mobile crane able to lift the heaviest piece — usually a counterweight block or a jib section. Think about dismantling too: by the end of the job the crane will stand "inside" the finished building.
10. Total cost
Compare not only the monthly rental but also transport, erection, climbing and ties, operators, maintenance and dismantling. Sometimes a crane one class bigger works out cheaper because it covers the site from one position instead of two.
The Kranovshik catalog helps with the first step: filter tower cranes by capacity and manufacturer and compare up to four models side by side. The final choice is made from the manufacturer's load diagram for the chosen jib length.