“We have also seen some concepts involving tandem lift straddle carriers, but tandem lift has yet to be fully utilised in ship-to-shore cranes operations,” says Paul Bolger, technical sales engineer at Liebherr Container Cranes. “At Liebherr, we have already provided customers with tandem lift cranes so people are gearing up for tandem lift, but it’s definitely not mainstream yet.”
Technically, he sees few problems in adapting the classic straddle carrier or aspects of the RTG design to carry two laden containers side-by-side.
Jost Dämmgen, Konecranes sale manager for port cranes, however, is yet to be convinced by such a concept.
“Such units would have to be double the width of existing designs with a concomitant reduction in speed, meaning there would only be a very small niche market for them,” he says.
Furthermore, operators would need to seriously consider changing their entire fleet of straddle carriers, because double width units would not run comfortably alongside conventional straddle carriers, because of the need to totally rearrange the stacking yard.
“I would also be worried about the stability of such a unit,” he says.
Instead, he believes the future of this market revolves around six-wheel units operating at speeds of 40-50km/h in twin pick, two-high mode.