In large docks or ports you often see multiple gantry cranes working together on one railing system. The crane operator is usually more focused on the container than on a second portal crane. Should two portal cranes collide, both would need to be repaired, significantly reducing the total productivity of the trading facility. To eliminate this potential risk, logistics specialist C. Steinweg - Handelsveem B.V., based in Rotterdam Port in the Netherlands, worked together with Micro-Epsilon to implement a solution based on optoNCDT ILR 1021 laser distance sensors. optoNCDT ILR 1021 sensors use the principle of light travel time measurements. A laser diode within the sensor creates short laser pulses that are projected onto the measuring object. The sensor element captures the light reflected off the measuring object. The time that it takes the light pulses to travel to the measuring object and back indicates the measuring distance. optoNCDT ILR 1021 sensors are mounted on the gantry crane bases, in direction of the adjacent crane with a measuring range of 30m. A reflector plate is mounted on the second crane. When the second crane comes within the sensor's measuring range, a warning is issued. If the gantry crane comes within a distance of 20m, it will be prevented from travelling any further.