On Potain’s published data sheet for its MDT 109 tower crane, one type of base needs 20 tonnes of ballast when the crane stands 19.3 m tall and up to 125 tonnes when it stands 54.3 m tall. That jump explains what a tower crane foundation is for: the concrete block, ballasted steel base or rail track under the mast has to hold the crane upright against the wind on a tall tower as much as against the load on the hook.

In India the builder, not the crane hire firm, usually designs and builds that base from loads the supplier gives in writing. This guide covers who is responsible, the loads, the base types, ballast and size, the site checks, and how a tower crane is erected and climbs. Figures come from NBC 2016, IS 6521 (Part 1), IS 13367 (Part 1) and Potain and ACE data, read on 3 and 6 November 2026. No prices are quoted.

Who designs a tower crane foundation in India?

The client does, which on a building job usually means the builder or main contractor. NBC 2016 Part 7, clause 7.3, says tower cranes are usually supplied on hire, with the client responsible for the design and construction of the base the crane stands on. The crane supplier provides the details of loading. The base is most often designed as a temporary structure, though sometimes it is built into the permanent structure to save cost and time.

IS 13367 (Part 1):1992, the Indian code for the safe use of cranes, says the same from the site’s side. Under clause 10.2 the appointed person, meaning whoever is in charge of the lifting work, must make sure the ground or support can carry the crane’s loads, as assessed by a competent person, using loads from the crane manufacturer.

So three parties share the job. The supplier gives the loads, the base drawing and the erection manual. A structural engineer designs the base for this site’s soil. The contractor builds it. Take away any one of the three and the base is a guess.

What loads does a tower crane base have to carry?

A tower crane base carries four things at once, as IS 13367 (Part 1) clause 10.2 lists them: the dead weight of the crane with its counterweight and ballast, the load and lifting gear, the dynamic forces from the crane moving, and the wind, up to the maximum permitted for how exposed the site is.

Wind is what sets a tower crane base apart from a machine footing. A tall mast and long jib catch a lot of it, and the higher the push, the bigger its tipping effect at the base. Engineers call that the overturning moment. The base resists it with its weight and its spread.

NBC 2016 clause 7.3 says the supplier gives loads in two forms: in service, while the crane works and stops in high wind, and out of service, when it is parked and the highest wind may come. IS 13367 adds that working loads are usually bigger, that the other cases must still be checked, and that the forces will not be spread evenly.

Load case When it applies What the code says about it
In service The crane is working; it stops lifting above its set wind speed IS 6521 (Part 1) clause 8.1: in any working position, with a steady wind pressure of 25 kgf/m², the crane must not tip even with twice its maximum safe working load on the hook
Out of service The crane is parked, possibly through a storm IS 6521 (Part 1) clause 8.2: the crane must stay stable under the maximum wind for its zone of the country (IS 875), with the jib at maximum radius and free to slew
Erection and dismantling The crane is part-built, with sections being added or removed IS 13367 (Part 1) clause 10.2: must be taken into account alongside the other two

IS 6521 clause 8.2.1 adds a point that matters for the base designer: rail clamps and guy ropes do not count towards stability. The crane has to stand up on its own weight, its ballast and its base.

What are the types of tower crane foundation?

There are six common ways to hold a tower crane down, and the soil and the crane decide which one a site uses. Potain’s MDT 109 data sheet, for one, offers the same crane on cast-in fixing angles or on several ballasted cross-bases.

Base type How it holds the crane Where it suits
Fixing angles in a concrete block Steel anchor feet, called fixing angles, are cast into a reinforced concrete block and the first mast section bolts onto them Static top-slewing cranes on firm ground with room for a block
Ballasted cross-base A steel cross of girders sits on the ground or a slab and is loaded with concrete ballast blocks Static cranes whose data sheet offers a cross-base; the ballast leaves the site with the crane
Rail track The crane runs on two rails with wheels at each corner and enough ballast to keep the load on the rails Long sites where one crane must travel along the building
Outrigger pads A self-erecting crane stands on four outriggers, each on its own pad, with ballast at the foot of the mast Low-rise housing and smaller builder jobs
Pile foundation A pile cap under the base carries the load down to firm strata Particularly poor ground, filled land, soft clay
Base inside the building The crane base is built into the raft or basement of the permanent structure Tight city plots and tall towers where the crane sits in the building footprint

NBC 2016 clause 7.3 gives the ground rules. Compacted structural fill can carry a crane where possible, with the load spreading through layers of track support at 45 degrees into the soil. Heavier loads may need reinforced concrete, such as beams carrying the crane’s line loads. Very poor ground may need piles, designed so the pile-top steel does not get in the way of the mast base section.

Rail-mounted cranes, the clause says, typically run on two rails 4.5 m to 10 m apart with wheels at each corner. They are not normally tied down, so enough kentledge (dead weight used as ballast) must keep the vertical load passing through the rails. IS 6521 (Part 1) Appendix D wants the track designed by a competent person, laid level on foundations or sleepers that suit the wheel load, and inspected regularly.

A self-erecting crane, the kind that unfolds itself and carries its ballast at the foot of the mast, needs the least ground work. Potain’s Evy 30-23 4 t has a 4 m by 4 m footprint, weighs 10,500 kg without ballast and takes 18,800 kg of ballast in one set-up, by its flyer and data sheet. Its pads still need ground that can take the support loads.

How much ballast does a tower crane need?

It depends on how tall the crane stands without being tied to the building, and the amount rises faster than the height. The Potain MDT 109 sheet (EN 14439 C25-D25 edition) lists base ballast for its ZD 440 cross-base with a 1.6 m mast. With a 40 m jib, the ballast goes from 20 tonnes at 19.3 m height under hook to 125 tonnes at 54.3 m.

Base ballast against free-standing height: Potain MDT 109, ZD 440 cross-base, 40 m jib

54.3 m125 t
49.3 m100 t
44.3 m70 t
39.3 m50 t
34.3 m40 t
29.3 m30 t
24.3 m20 t
19.3 m20 t

Height under hook on the left, base ballast on the right. Figures from the Potain MDT 109 data sheet, EN 14439 C25-D25 edition, read 6 November 2026.

Look at the shape. From 19.3 m to 34.3 m the ballast only doubles, 20 to 40 tonnes. The next 20 metres roughly triple it again. A taller mast puts the wind’s push higher and gives it more steel to push on, so the tipping effect grows faster than the height. That is why tall towers are tied to the building instead.

Wind class moves the figure too. Potain prints the same crane on a second sheet for another wind class, EN 14439 C50-D50, where the ZD 440 base needs 120 tonnes at 49.3 m instead of 100 and its free-standing limit drops from 54.3 m to 50.9 m. In India, IS 6521 clause 8.2 points to IS 875 for the out-of-service wind in each zone, so a crane on a coastal site can need a different set-up from the same crane inland.

IS 6521 clause 8.4 also says the ballast weight and position must be shown clearly and permanently on the crane. Count the blocks against that marking before the crane starts work.

How big should a tower crane foundation be?

No code gives one size, because it comes from the crane’s loads and your soil. NBC 2016 clause 7.3 sets the test: the unfactored loading and pressure from the crane, meaning the actual loads without design safety multipliers, must stay below the soil’s allowable bearing pressure.

NBC 2016 Part 6, Section 2, clause 7.2.2 says how that pressure is fixed. It is the lower of the safe bearing capacity from the soil’s shear strength, with a factor of safety of 2.5, and the pressure the soil takes without settling too much. A plate load test on site is one way to measure it. If a weaker layer lies below, the pressure reaching it must not exceed what it can carry, so the soil report matters more than the crane’s size.

Here is how the numbers meet, as our own arithmetic on the Evy 30-23 sheet with an example soil figure. The sheet’s heaviest load on one support is 20.3 tonnes, about 199 kN (20.3 × 9.81). At an allowable bearing pressure of 100 kN/m², each pad needs at least 199 ÷ 100 = about 2 m², roughly a 1.42 m square. On ground rated at half that, the area doubles.

Wind changes the soil check as well. Clause 7.2.2.4.1 says wind may be ignored where it adds under 25 percent to the bearing pressure from dead and imposed loads. Above that, the combined pressure may exceed the allowable figure by up to 25 percent. On a tall free-standing crane the wind share can be large, so the engineer checks both.

Depth follows the same logic. There is no standard depth for a tower crane foundation: it goes down to soil that can carry the pressure, deep enough for the anchor feet or pile caps and clear of services. The design drawing sets it.

What should a site check before the base is built?

Most base problems start before any concrete is poured. Work through these checks with the supplier and your engineer:

  1. Get a soil report for the crane’s exact position, not only for the building.
  2. Get the supplier’s written loads for this crane, jib and height, in service, out of service and during erection, with the base drawing and the erection manual.
  3. Place the crane for the widest useful radius. Where two cranes share a site, NBC clause 7.3 wants their mast heights and jib lengths planned together.
  4. Check what the jib swings over. Near an airport the crane needs height clearance too; see the AAI NOC for height clearance.
  5. Trace underground services. IS 13367 clause 10.3.1 wants the crane foundation clear of gas mains and cables, or those services protected.
  6. Measure to overhead lines. Under clause 10.3.2 the Electricity Board must be consulted if the crane, jib included, works within 15 m of lines on steel towers or 9 m of lines on poles.
  7. Plan access for the trailers and the assembly crane; clause 10.1 counts room for erection and dismantling as a siting point.
  8. Plan power at the base. Clause 11.4 asks for an effective earth, protected cables and an isolator away from the crane. Decide between grid and a diesel generator now.
  9. For a rail-mounted crane, keep 900 mm clear of any obstacle along its path (clause 10.3.1) and bond and earth the rails (clause 11.4).

Building the base is ordinary site work. An excavator digs the pit, a transit mixer brings the concrete and a stationary concrete pump places it, the same machines listed in the guide to equipment used in high-rise building construction. Fixing angles go exactly where the supplier’s drawing puts them before the pour. Ask the engineer what strength the concrete must reach before erection, and confirm it with a cube test.

How is a tower crane erected?

A top-slewing tower crane is usually assembled onto the finished base by a larger telescopic mobile crane with more reach. A self-erecting crane travels as one unit and unfolds itself without a support crane.

IS 13367 (Part 1) clause 11.1 treats erection and dismantling as lifting operations, planned and supervised the same way. It asks that:

  • erection does not start until an instruction manual that the crew understands is on site;
  • the manual is the right one for that crane and carries the maker’s serial and type number;
  • one erector in charge controls the whole operation;
  • everyone involved knows their part;
  • any change to the maker’s procedure is approved by the designer or another competent engineer;
  • only correct replacement parts are used.

Clause 11.3 adds a check worth making on any crane that has been rebuilt or brought in from abroad: load-bearing parts must carry identification marks that match the manual, imperial and metric bolts must not be mixed, and high-tensile bolts must be marked.

Plan the way down too. The note to clause 11.1 says the plan should cover dismantling. A tall tower that climbed with the building may be taken down by a smaller crane lifted onto the roof, which can be harder than putting it up. Once standing, every lift follows the tower crane load chart, and the checks in crane safety rules and training apply from day one.

Lifting at ground level around a site that keeps changing, such as shifting steel or precast pieces, is pick-and-carry work, and the other lifting machines are covered in the crane guides. Compare crane models and specifications and connect with a verified dealer.

How does a tower crane climb as the building rises?

A tower crane climbs by raising itself on a hydraulic jacking frame, often called a climbing frame or climbing cage, and adding a new mast section each time. Above a certain height it must also be tied to the building with collars and ties, so the structure helps hold it up.

The height a crane can stand without ties is its free-standing height. ACE, the Indian maker, publishes it beside the tied maximum for every model:

ACE model Jib length Free-standing height Maximum height (tied)
TC 5034 50 m 34 m 103.5 m
TC 5540 55 m 40 m 140 m
TC 6552 65 m 52 m 200 m
TC 7074 70 m 74 m 275 m

From ACE’s tower crane range page, read 3 November 2026. The model number gives jib length then free-standing height, as the load chart guide explains.

Everything above the free-standing height is reached by climbing and tying. Potain’s MDT 109 sheet shows the same pattern: free-standing heights of 35.4 m to 54.3 m by base and mast, and an anchorage table running past 200 m.

Ties pass part of the crane’s load and wind force into the building, so the floors or columns that take them become part of its support. IS 13367 clause 10.2 covers “the ground or any means of support”, so a competent person checks those members for the tie loads, as the soil was checked for the base. Agree tie levels and loads with the building’s structural engineer before the crane reaches them.

Treat each climb like erection. Clause 11.2 says the maker’s instructions must be followed closely and any change to the sequence checked by the designer or another competent engineer, so the crane stays stable and no part is overloaded. Self-erecting cranes cannot climb, which keeps them on low-rise work.

Sources

Base design, load cases, rails, kentledge, fill, beams and piles: NBC 2016 Part 7 clause 7.3, read from the archive.org copy of NBC 2016 Volume 2. Bearing pressure and wind: NBC 2016 Part 6, Section 2, clause 7.2.2. Stability, wind pressure, ballast marking and track: IS 6521 (Part 1):1972, the tower crane design code NBC names; it dates from 1972, so check for a later edition. Siting, services, overhead lines, erection and electrics: IS 13367 (Part 1):1992. MDT 109 figures: the C25-D25 and C50-D50 data sheets on Potain’s MDT 109 page, read 6 November 2026. Evy 30-23 4 t and ACE figures: their maker pages, read 3 November 2026. The pad-area example is our own arithmetic.

Prices, specifications and features are indicative, vary by variant, location and date, and should always be confirmed with the official OEM or authorised dealer before any purchase decision. DesiMachines is not liable for decisions taken on the basis of information that may have changed after publication.