Wirtgen has introduced the "Auto-Edge" intelligent control package for its SP 500 series slipform concrete pavers. Slipforming curbs, medians, and concrete barriers demands that the machine follow the design alignment with centimeter accuracy while extruding fresh concrete at a consistent rate. Traditionally, this requires a physical stringline tensioned along the entire job length-hours of surveying and stake-setting labor-and the paver operator must also constantly judge the concrete consistency by eye, adjusting the travel speed to avoid slumping or tearing of the fresh extrusion.
The Auto-Edge package eliminates the stringline. The engineering core is the "Dual-Antenna GNSS Steering System." Two roof-mounted GNSS antennas, corrected by an RTK base station, determine both the machine's position and its heading vector. A steering controller actuates the paver's track-drive steering cylinders directly. Because slipform pavers crawl at less than 2 m/min, even a small heading error accumulates into visible curb wander; the dual-antenna arrangement provides heading resolution of 0.02 degrees, allowing the machine to hold the design line within ±10 mm over a 500-meter pour.
The second innovation is the "Concrete Workability Sensor." A submersible pressure transducer is mounted inside the concrete hopper, along with a paddle-type flow resistance probe at the auger. The system continuously infers the slump of the fresh mix from the power draw of the auger drive. If a stiff batch of low-slump concrete arrives, the system automatically slows the paver's travel speed and increases the vibrators' amplitude so the extrusion remains dense and free of honeycombing-without waiting for the operator to notice a visual change at the mold. Field results on a 12-kilometer highway barrier project showed zero line correction stops and an 85% reduction in surveying labor compared with stringline operation.
