How to Choose a Tower Crane: Capacity, Reach and Cost

A tower crane is usually the single most constraint-defining machine on a build. Get the specification wrong and you either cannot lift what you need where you need it, or you pay for far more crane than the job requires. Four numbers do most of the work in getting it right.

1. Tip load, not just maximum capacity

Every tower crane has a headline maximum capacity — the heaviest load it can handle, lifted close to the mast. That figure is rarely the one that matters. What counts is the tip load: how much it can lift at the far end of the jib, where your heaviest awkward lifts often happen.

Capacity falls with radius along a load chart. A crane advertised at 12 tonnes might manage only 2.3 tonnes at a 50-metre radius. Start from your heaviest load at its furthest required position and read the chart backwards.

2. Jib length and working radius

The jib has to reach every point you need to service, including across the building footprint and any laydown areas. Longer jibs cost capacity, so do not over-specify reach you will not use. Map the site, mark the furthest pick and place points, and choose the shortest jib that covers them.

3. Hook height

Hook height has to clear the finished structure plus the tallest load, the slings, and a safety margin. For a free-standing crane there is a maximum height the manufacturer allows before the mast must be tied into the building. Going beyond the free-standing limit adds tie-in engineering and cost, so confirm it early.

4. Free-standing height and foundations

Free-standing height drives the foundation design and the erection plan. Taller free-standing configurations need heavier ballast or a deeper foundation. This is where site constraints — ground conditions, access for the mobile crane that erects the tower crane — start to dominate the decision.

Match the crane to the access model

Tower cranes spend most of their life between jobs doing nothing. That is why the access question matters as much as the specification:

• A single build of fixed duration: rent. You avoid transport, erection, dismantling and idle storage between projects.
• A pipeline of overlapping projects in one region: a longer-term lease can lower the monthly cost while keeping flexibility.
• Near-continuous use across many sites for years: ownership may pay off, but factor in maintenance, certification and storage.

For the wider trade-off, see rent, lease or finance equipment, and put your figures through the rent vs lease vs buy calculator before committing.

A quick specification checklist

• Heaviest load and the radius it sits at
• Furthest pick-and-place points on the site
• Required hook height over the finished structure
• Free-standing height versus tie-in needs
• Site access for erection and ground-bearing capacity

Settle these five and the shortlist of suitable cranes becomes short and obvious.