by introducing additional fresh material under the sleepers, e.g. by the measured-shovel method, by the blowing method

Full Title

Placing, renewing, working, cleaning, or taking-up the ballast, with or without concurrent work on the track; Devices therefor; Packing sleepers > Packing sleepers, with or without concurrent work on the track; Compacting track-carrying ballast > Packing sleepers, with or without concurrent work on the track (preforming ballast cores or seats for sleepers E01B27/02) > Sleeper-tamping machines > by introducing additional fresh material under the sleepers, e.g. by the measured-shovel method, by the blowing method