Green Cargo switches driverless freight trains

Locomote - Green Cargo - ctl00_cph1_image

The 90-ton freight locomotive rolls softly into Green Cargo’s switching yard at pre-set, precision speed—without a driver. Using wireless technology, the locomotive is controlled by the switch crew in the switching tower or in the yard. Work at the shunting yard in Borlänge, Sweden has become safer and more effective—thanks to a locomotive remote-control solution from Åkerströms.

Forty trains with nearly 1000 cars are switched within a 24-hour period at Green Cargo’s switching yard in Borlänge. When a freight locomotive rolls into the yard, the yard operator switches the locomotive to the right track; the maneuver is done totally via remote control. And the switching tower crew has already entered into the computer the tracks onto which the locomotives and freight cars will be driven. There, they are coupled again so that they can eventually continue their journey to their final destination in Sweden or Europe.

Safety and effectiveness
Using Locomote, Åkerströms’ remote control for locomotives, operators in the shunting yard or the tower, switch the driverless train. And with a transmitter positioned on the operator’s abdomen, remote control for locomotives is simply executed with a joystick—a little like driving a model train only for real. Coupling freight cars is a time-consuming procedure that’s become a lot shorter during the past few years. Faster, safer technologies and smart planning are perhaps the primary reasons. Earlier, engines were manually driven, and this required at least two persons. Today, one person can do the same job. Taken together, all these improvements have increased safety and switching effectiveness at Green Cargo.

“Remote control of locomotives has clearly made our working environment much safer,” explains Leif Boogh, production technician at Green Cargo. “The switching crew’s job is dangerous. Here at the Borlänge switching yard, misunderstandings sometimes came up between the switching operator, the switching manager in the tower, and the locomotive driver. Fifteen years ago, we had an average of about 17 incidents per month. Now we have less than two.”

Increased effectiveness is another very important reason why Green Cargo invested in radio-control technology. Faster, safer shunting increases effectiveness and thus the railroad’s chances of competing with other transportation alternatives. This enabled us to adjust our costs so we could offer a competitive alternative on the Swedish and continental European markets.”

“The first radio-based applications were implemented already in 1967,” says Mats Granath, planning manager at Green Cargo, “and implementation accelerated during the 1990s when the rebuilding of radio locomotives was adapted for the programmable logic control (PLC) system, which Green Cargo developed. Since the mid-1980s, we have rebuilt 126 locomotives, which enabled substantial effectiveness that has been critical for our competitiveness. We were also able to save because we rebuilt the locomotives rather than buying new ones.”The cost of rebuilding a locomotive with radio remote-control is only a small part of the total cost of rebuilding, which in fact yields a fully functioning, modern locomotive for a fraction of the price for a new one.

Another benefit from controlling the locomotive from the switching yard and from the tower is that the yard operators need not get up and down from the locomotive’s cab, which is a step or hop of more than three feet (one meter). The operator has full control and sees what’s happening all the time. Earlier, when the locomotive was manually operated, driving styles varied, depending on who was running it. Now, everything is preprogrammed and all locomotives are run the same way, so there are fewer injuries.

Control from the shunting yard or the tower
The technology works like this: at the start of a work shift, the operator simply presses buttons to program which transmitter will be used to control the locomotive. A receiver resides within the locomotive and captures the transmitter’s signals when the operator starts to move the locomotive. The signals then communicate with Green Cargo’s PLC, which is a programmable control system. Åkerströms equipment is totally compatible with this software.

Tower control at Borlänge makes freight car shunting more efficient. From the tower, the crew has a good view of the entire shunting yard and everything that’s going on. This contributes to a safer, more effective working environment. A computerized traffic planning system is housed in the tower from which the different tracks and the coupling and uncoupling of the cars are coordinated. There’s also parallel remote control for locomotives (Locomote Tower Control) that makes it easy to take over the command from the yard operator, if necessary. Although the operator in the yard is always the one who decides who’s in charge—the operator or the tower. The reason for this is simple: the operator is closest to the locomotive and sees what’s happening and must be able to make a fast stop if required. Wireless communication ensures that the operator’s transmitter or the tower’s signals and commands are transmitted to the locomotive’s receiver. The receiver then further transmits the signal, via a profibus cable, to the PLC system that then executes the command.

222 radio-controlled locomotives in seven switching yards with tower control
Borlänge is one of Sweden’s six switching yards in which tower control is used. The others are in Gothenburg, Helsingborg, Gävle, Sundsvall, Malmö, and soon in Hallsberg. Since 1991, all Green Cargo’s locomotives have been rebuilt to radio locomotives, which the switching crew controls remotely. At the same time, the company also started development of tower-controlled locomotives in Borlänge. Now the radio-control system is successively being installed in other shunting yards. In the mid-1990s, Åkerströms started to cooperate with Green Cargo to develop remote control. Today, 222 of Green Cargo’s locomotives are equipped with Åkerströms’ Locomote solution. The plan is to equip the majority of Green Cargo’s locomotives with radio control, which gives the company increased flexibility and efficiency within its operation because the same locomotive that pulls the cargo cars can also be used as a remote-controlled switching locomotive.

“We have a very good partnership,” says Boogh. “Åkerströms is accessible, flexible, and sensitive to our needs. We’re continuously developing solutions together. What we perhaps like best is that the transmitters are adapted for our needs and that the new ones are ergonomically designed. This is incredibly important aspect of safety that also reduces risk for work-related injuries.”

About Green Cargo’s self-developed programmable logic control (PLC) system
The system contains a power supply unit, input and output cards for digital and analogue signals, and a control unit, i.e., a central processing unit (CPU).