Rail-mounted gantry cranes (RMGs) are a hot discussion topic at container ports these days. Many port authorities, terminal operators, and shipping lines are taking a keen interest in how facilities with RMGs perform, and how their own facilities might some day use the technology. This article discusses RMG options that were studied at Jebel Ali in Dubai and at the New York Container Terminal (NYCT). The results at these very different facilities were illuminating.
The JWD division of DMJM Harris, acting as a subconsultant to Halcrow HPA, prepared conceptual plans for Jebel Ali Terminal 2. We prepared simulation analyses that studied options for endloaded and side-loaded RMGs, comparing them to other, more conventional yard-handling options. The end-loaded option included pairs of end-loaded, portal-frame RMGs perpendicular to the wharf (see Figure 1). When automation is included, this arrangement is called an automatic stacking crane (ASC) system.
Facilities currently using this technology, albeit with differing layouts, include CTA in Hamburg (with nested pairs of RMGs per run that can pass each other), and ECT in the Netherlands (with a single RMG per run). For our study, the Dubai Ports Authority (DPA) selected the comparison option of matchedgage RMGs in pairs. For waterside transport, options included automated and manual shuttle carriers, automatic guided vehicles (AGVs), and conventional yard-tractor/trailer combinations.
The side-loaded RMG option included double-cantilever RMGs parallel to the wharf with wharf-to-yard transport provided by either shuttle carriers or yard-tractor/trailer combinations (see Figure 2). DMJM Harris had previously prepared similar conceptual plans for terminals that are now operating at Pusan Newport, South Korea, and Haifa, Israel. Other installations include HIT in Hong Kong and T-5 in Kaohsiung, Taiwan. Sideloaded, cantilever RMGs are also commonly used in intermodal rail yards.
Detailed terminal simulations were prepared to show overall on-terminal traffic movement with each transport option. The cantilever RMG layout had higher expected productivity (35.5 lifts per hour) than the ASC (33.6) and RTG (29.0) options. The cantilever RMG layout also had a relatively low variable cost per lift (US$15.60) compared to the ASC (US$18.70) and RTG (US$14.90) options. Ultimately, DPA decided to use double-cantilever RMGs served by tractor-trailers in the first phase of the multiphase development. Tractors won out over shuttle carriers partly because tractors parked close together under the quay cranes were expected to supporttandem-lift operations better than shuttle carriers. The terminal will be configured with storage areas for loaded containers stacked 6 high by 10 wide in grounded stacks, serviced by 31.2 m gage, eight-wheel, electric-powered, double-cantilever RMGs capable of lifting one container over a 6-high stack. The RMGs will run parallel to the wharf.
One element driving that decision was that labour costs in the area are very low. Therefore, any potential automation could not be expected to generate a large reduction in labor costs. A second element driving the decision was the perceived lower risk of delay to start-up for the selected operation. DPA’s critical requirement
was its extremely aggressive schedule.