Specially trained staff must erect tower cranes. When a crane is erected, it is necessary to follow the supplier’s instructions;in particular as regards the base, tolerances, securing of crane rails, etc. Following erection, the crane must be reported and test-loaded.
The crane must be placed on a load-bearing base at a safe distance from steep slopes and excavations. Moving parts on the crane must not cause a risk of trapping; the distance between crane parts and buildings, structures and material must be at least 0.50 m.
During erection, it is important to:
- Set up a sign showing the permissible load.
- Check the height stop, operation end stop and emergency stop.
- Check signalling devices (bell/horn).
- Make sure there is an instruction manual and logs in the driver’s cab.
- Test drive the crane together with the crane driver so that any faults are rectified before the installer leaves the site.
There must be a personnel hoist on the crane when the access route to the driver’s cab is more than 25 m. However, this is necessary only if the crane has been standing for more than 2 months and this is possible in practical and technical terms.
There must be warning signs bearing the words: “Gå ikke under hængende last.” [Do not walk beneath suspended loads.] when the crane is used in areas where people are moving around. These signs must be visible and readily legible.
Requirements for crane rails:
- The crane rail must be placed on a load-bearing surface. Materials which may become wet and thereby impair the stability of the crane must be dug out and replaced with some other load-bearing material (such as broken stone ballast, laid out in thin layers and rolled after each application).
- Where necessary, the craneway can be cast in concrete in accordance with the instruction manual.
- The crane rail must be drained and the rails aligned so that the tolerances for distance and height difference can be observed.
- Rail support must be implemented so that rigid jointing of the rail ends is assured. These are supported by double or particularly wide transverse sleepers.
- The track must be laid so as to ensure a safe distance between the rails to steep slopes, excavations, stationary parts and material stores.
When the rails are laid, it is necessary to check that:
- the span has been checked and found to be correct, and that the dimensions and tolerances prescribed by the supplier have been observed – and that there is a smooth transition to driving around corners,
- the rails have fixed end stops applied to each rail and sufficiently far away, but at least 30 cm, from the outermost rail support. These end stops must be applied so that the stops at the same end of the track are touched by the crane at the same time,
- operation end stops for the machinery are applied such that the crane is braked fully before the fixed end stops are reached,
- bogies (drive wheels) stand straight on the rails and that they have had cowcatchers, guard units and rail claws fitted,
- the crane is fitted with devices which prevent it from tipping over if an axle breaks or the crane is derailed.’
A crane moving on rails must not be able to collide with people, e.g. in situations in which a full overview of the driving area is not possible. This can be rectified by cordoning off the driving area or by providing the crane with yielding contact stops. Crane rails should be checked by driving through the bends before the fitters leave the site.
If there are a number of tower cranes on the same site, they must not be able to collide with one another. When parking, the jib must be able to yaw freely in the wind without risking colliding with other cranes or building elements.