EXPERT COLUMN | LEEA
The right bridge and gantry crane for the job
E
lectric bridge and gantry cranes provide a means of lifting and transporting loads in factories, warehouses, ports,
shipyards and construction sites among other environments. An electric bridge crane runs on an elevated runway system along the ceiling of a building. A gantry crane is similar in function to a bridge crane but it stands on legs and does not require a building structure to support it. Both cranes can be used indoors and out. The
difference between the two is really that, with a gantry crane, the long travel drives are positioned at the bottom of the legs which form part of the crane structure. A bridge crane has the long travel drives at the ends of the bridge beam. Deciding what type of crane to use will be heavily influenced by where it is to be installed, which consist of four main likely situations.
1. An indoor crane for a new building: If the crane is to span the whole width of the building, the most likely choice will be a bridge crane. The supporting structure can be designed as an integral part of the building structure. If the crane is to span only part of the building width, there are four options to consider. The first of these is an under-slung bridge crane running on tracks suspended from the building. Second is a semi-gantry crane, which is only suitable if the crane span is to reach one side of the building. The third option is a gantry crane. Finally, there is the option of a top running bridge crane with one or both sides supported on a free-standing supporting structure. While this has the disadvantage of a permanent supporting structure obstructing part of the floor, it may be suitable if only a short travel run is required. It is essential to decide which option to use early in the building design process so the required capacity, span, travel and height of lift can be accommodated. Allowances also need to be made for loadings imposed by the crane on the building, supporting structure and ground. It is important that building designers are familiar with designing structures for use with
10 | November 2025 |
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electric bridge and gantry cranes. Designs must incorporate the facility to accurately adjust the line, level and span of the supporting structure rails or crane tracks. Many buildings will be subject to movement over time and this will make it necessary to re-align the supporting structure or tracks. The type of building structure is another important consideration. Many modern buildings are constructed using portal frames, which can flex considerably under the influence of wind, snow and other imposed loads such as internal services, water tanks and so on. This flexing can result in an unacceptable variation of span. This can be limited with ties, but this should preferably be resolved at the design stage. Consideration must also be given to access for delivery and erection of the crane – which may be delivered fully assembled or not. The headroom required for a mobile crane to install it may require scheduling the installation for before the roof is completely covered. Similarly, access will be required for load testing the crane and supporting structure. This will involve travelling the crane under load down the length of the supporting structure. It should, therefore, be
Ben Dobbs
Technical Committee
Ben Dobbs, head of global standards and legislation at LEEA (Lifting Equipment Engineers Association), provides a brief guide on selecting the right bridge and gantry crane for the job.
scheduled before any plant, machinery or other obstacles are installed in the building.
2. An indoor crane for an existing building: In this situation, much will depend upon the design of the building. The options for the type of crane are essentially the same as for a new building but if the building was not designed to accommodate electric bridge or gantry cranes, it is highly unlikely that it will withstand the loads imposed without considerable strengthening or the installation of an independent supporting structure on new foundations. Also, the available headroom may not accommodate a crane of the required capacity spanning the full width of the building.
3. An outdoor crane alongside a new or existing building: The main options here are a top running bridge crane and a semi-gantry crane. The choice will depend upon whether the building will support crane tracks on that side and the length of travel required. For the length of travel, it is a cost balance between the more expensive semi-gantry crane and the cheaper ground level track. Consideration must be given to the possible hazards arising from the crane leg and the ground level track.
4. An outdoor crane in an open area: The only real options here are a top running bridge crane with an independent supporting structure or a gantry crane. The decision is likely to depend upon the length of travel required balancing the cost of the more expensive bridge crane supporting structure and track against the cheaper ground level track. Again, consideration must be given to the possible hazards caused by the crane legs and the ground level tracks.
For more best practice information on bridge and gantry cranes, consult the LEEA COPSULE (Code of Practice for the Safe Use of Lifting Equipment), which is free to download at
leeaint.com.
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