Choosing the right runway beam is one of the most important structural decisions in any overhead crane installation.
The beam carries the full dynamic load of the crane, the hoist and the lifted load across every cycle of operation. Get the specification wrong and the consequences range from accelerated wear and unplanned downtime to structural failure and serious injury.
Learn from the crane experts here at Metreel about the 5 main types of crane runway beams used in UK industrial facilities, what distinguishes each one and the factors that should inform your choice.
What Is A Crane Runway Beam?
A crane runway beam is the structural element that the overhead crane travels along.
In a top running crane system, the runway beam sits on top of building columns or a freestanding support structure and carries a rail on its upper flange.
In an underslung system, the crane’s end carriages hang from the lower flange of the beam and travel along its underside.
The runway beam provides both vertical support for the weight of the crane and lateral resistance against the horizontal forces generated during travel, acceleration and load swing. Its section, material and connection method must be designed to handle all of these loads over the intended service life of the installation.
The Main Types of Crane Runway Beam
Different types of crane runway beam exist because no single section can efficiently serve every application. The loads a runway beam must carry vary enormously depending on the crane’s safe working load, its duty cycle, the span between supports and the speed at which it travels.
For instance, a light monorail in a small assembly facility and a heavy overhead travelling crane in a steel fabrication plant are fundamentally different structural problems. The beam must be matched to the specific combination of vertical load, horizontal force and fatigue demand in each case. Building constraints, available headroom and budget all add further variables.
The result is the following range of beam types, each offering a different balance of strength, stiffness, weight and cost to suit the conditions it will face.
1. Rolled I-Section Beam (Universal Beam)
The rolled I-section, commonly referred to as a universal beam (UB) or I-beam, is the most widely used runway beam type for light to medium-duty applications. It is produced by hot rolling steel into an I-shaped profile and is available in a wide range of standard sizes.
The key advantage of a rolled section is cost and availability. Because it is a standard product, lead times are short and fabrication requirements are minimal. For installations with moderate spans, standard crane classifications and no exceptional environmental demands, a rolled I-section is often the most practical choice.
However, rolled I-sections have limitations. The flange width and thickness are fixed by the standard profile, which can restrict their ability to handle high horizontal loads without additional reinforcement. For underslung cranes, the taper of the lower flange must be matched to the end carriage wheel profile to ensure correct bearing contact.
Typical applications: Monorail systems, light overhead cranes, workstation crane systems, underslung cranes in warehouses and assembly facilities.
2. Rolled I-Section With Horizontal Reinforcement
Where horizontal loads are significant, a standard rolled I-section can be reinforced by welding a horizontal plate or channel section to the top or bottom flange. This increases the beam’s resistance to lateral forces without requiring a fully fabricated section.
This approach is common in installations where the crane operates with long spans, high travel speeds or frequent load swing, all of which generate elevated horizontal forces at the runway level. It provides a cost-effective middle ground between a standard rolled section and a fully welded beam.
The reinforcement must be designed and specified by a structural engineer with knowledge of the crane’s wheel loads and duty cycle. Incorrectly sized reinforcement can give a false sense of security without providing the additional strength actually required.
Typical applications: Medium-duty overhead cranes, longer span runways, installations where horizontal load transfer to the building structure needs to be managed carefully.
3. Welded I-Section Beam (Plate Girder)
A welded I-section beam, also known as a plate girder, is fabricated from flat steel plates by welding together a top flange, a web and a bottom flange. Unlike a rolled section, the dimensions of each element can be specified independently, which allows the beam to be optimised for the precise loading conditions of the installation.
This flexibility makes welded I-sections the preferred choice for heavier cranes, longer spans and high-duty-cycle applications where the demands exceed what a standard rolled profile can accommodate. The flange widths, web depth and plate thicknesses can all be adjusted to meet the required bending resistance, shear capacity and fatigue performance.
Welded sections require more fabrication time and cost than rolled sections, but for applications that genuinely require their capacity, they represent the correct engineering solution rather than an overspecification.
Typical applications: Heavy-duty overhead travelling cranes, long-span runways, high-cycle production environments, crane systems with SWLs above what standard rolled sections can efficiently carry.
4. Box Girder
A box girder is a closed rectangular section formed by welding together four plates: two flanges and two webs. The enclosed profile gives a box girder significantly greater torsional stiffness than an open I-section of equivalent weight, which makes it particularly well suited to installations where the beam is subject to eccentric loading or high torsional forces.
Box girders are typically used as the bridge beam on double girder overhead cranes rather than as runway beams, but they are used in runway applications where spans are very long, loads are heavy or the structural configuration demands a high degree of lateral stiffness. Their fabrication is more complex and they are heavier than equivalent I-sections, so their use in runway beams is generally reserved for applications where the performance characteristics genuinely justify the additional cost.
Typical applications: Very long span runways, heavy industrial cranes, specialist installations requiring high torsional stiffness.
5. Lightweight Aluminium or Steel Profile Section
For lighter duty applications, particularly in assembly, maintenance and production workstation environments, extruded aluminium or cold-formed steel profile sections are used as runway beams. These profiles are designed as complete systems and are typically supplied with matching end carriages, connection hardware and support components.
Profile systems offer fast installation, low self-weight and flexibility for reconfiguration if production layouts change. Their load capacity is limited compared to fabricated steel sections, but for workstation crane systems handling loads typically up to 2,000 kg they are a practical and cost-effective option.
In underslung applications, the end carriage wheels run on the lower flange of the profile, and the section geometry is precisely engineered to ensure smooth travel and correct wheel contact.
Typical applications: Workstation cranes, light monorail systems, production and assembly cells, maintenance lifting points.
Top Running Versus Underslung Runway Beams
The type of crane installation affects how the runway beam is specified and used.
In a top running system, the crane’s end carriages run on rails mounted to the top flange of the runway beam. The rail is either welded directly to the beam or clamped to it using rail clips. Top running systems are the standard arrangement for heavier cranes and longer spans, as they maximise hook height and can accommodate higher load capacities.
In an underslung system, the end carriages hang from and travel along the lower flange of the runway beam. Underslung systems make use of the full available headroom below the beam, which is an advantage in low-headroom buildings. They are generally used for lighter duty applications and the lower flange geometry must be compatible with the end carriage wheel profile.
Rail Selection For Top Running Systems
In top running installations, the rail mounted to the runway beam is a critical component in its own right. Two main types are used:
Rail plates are used for lighter loads and standard duty applications. They are welded or bolted to the top flange of the beam.
A-rails (also known as crane rails) are used for heavier wheel loads and high-intensity use, including automated crane systems. Their profile distributes wheel loads more evenly and allows for horizontal guide wheels to be used in place of flanged wheels. A-rails are typically clamped at regular intervals to the runway profile rather than continuously welded, which allows for thermal movement and simplifies replacement.
The correct rail section must be matched to the wheel loads calculated from the crane specification. Undersizing the rail leads to accelerated wear, rail deformation and potential loss of alignment.
Key Factors When Specifying A Runway Beam
Crane classification and duty cycle. A crane used for occasional maintenance lifts places very different demands on a runway beam to one operating continuously in a production environment. The FEM or ISO duty class of the crane should inform the beam specification from the outset.
Span
Longer spans increase deflection under load. The runway beam must be specified to limit deflection to the tolerances required for the crane’s end carriages to function correctly and for the hoist to travel without binding.
Wheel Loads
The vertical and horizontal wheel loads from the crane’s end carriages are the primary design inputs for the runway beam. These must be provided by the crane manufacturer and used as the basis for the structural calculation.
Building Structure
Whether the runway is building-mounted, semi-freestanding or fully freestanding affects both the beam design and the load path into the supporting structure. A structural engineer should verify that the supporting columns, ties and foundations are adequate for the crane loads.
Environment
Corrosive environments, high temperatures or explosive atmospheres all affect the material specification, surface treatment and component selection for the runway system.
Discuss Your UK Crane Requirements With Metreel
Metreel designs and supplies overhead crane and runway systems for a wide range of industrial applications across the UK.
If you need guidance on the right runway beam specification for your facility, please get in touch with our team.
You can also give our crane experts a call on 0115 932 7010.