Abstract: A mobile arrangement for continuously laying a sand layer between a subgrade and ballast of a track bed in a construction section of the track comprises a work vehicle supported on undercarriages mounting the vehicle for mobility on the track in an operating direction. The work vehicle comprises a ballast excavating chain including a chain part receiving the excavated ballast. A ballast conveyor conveys ballast to the track section in the operating direction has an output end discharging the conveyed ballast in the track section. A device for planing the sand layer leads the output end in the operating direction, and a sand conveyor conveys sand to the track section in the operating direction. The sand conveyor has an output end discharging the conveyed sand in the track section and laying the sand layer, the output end being positioned between the excavating chain part and the planing device, and the ballast and sand conveyors in their entirety trailing the chain part in the operating direction.