Heavylift Tip – Barges

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Link-spans

A link-span is a method of spanning between a barge and a quayside, effectively a bridge which connects one to the other for the purpose of loading or unloading. This load transfer – or “Load-out/Load-in” – can be via wheels or skid system. To provide a smooth and safe transfer between the ship and shore, the link-span is commonly formed from steel sections.

Link-spans are formed of I beams, or column sections, welded toe to toe and come in various widths and lengths. As a method of securing the Link-span, these beams typically feature a hinge at one or both ends. These hinges are either fully pinned through eyes, or are the “pin in a U-shaped socket” type. When used with trailers, link-spans usually require wedges or slopes to allow the wheels to transition onto the link-span and off onto the quay or barge. Occasionally, either the quay or barge might have a recess which will eliminate one set of wedges.

A link-span is a vital piece of port equipment, where if not constructed correctly, can result in serious accident. Some issues to be aware of are:

• The longer the link-span, the deeper the section required (relative to the axle/skid load). The deeper the section, the more of the effective trailer stroke that is lost whilst crossing the link-span.
• Shorter boards can be a problem on berths with a large or rapid swell.
• Depending on the location of the link-span hinge, the barge may have to be always above or below the quay level during load-out
• Transporter clearances and low grillage height can be a problem if the grillages are within a half trailer length of the Link-span.
• Use of loose plates, instead of an engineered link-span system, is a high-risk alternative, because the plates can easily move, or be moved (even by SPMT drive axles), potentially falling between the barge and quay. Plates can also deflect, causing the plate edges to rise, in turn catching pipes and cables under a trailer, especially if the plate is shorter than the axle pitch, causing potential damage and delays.

For efficient loading and unloading, and to minimise turnaround time of ship to shore transfers, it is imperative to speak with a specialist about the function, limits, and types of link-spans available.

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