Official Directive from 1939

Railway Gravel Bed

§ 20. Bet fabrics
In tracks and soft 1. Order, only track gravel grain I (35 to 70 mm diameter) can be used. In heavily burdened tracks and soft 2. Order, a grain I can only be installed with particularly approved exceptions. In the other tracks and soft 2. Order and in soft 3. Order, Track Gravel Grain II (20 to 35 mm diameter) is to be used. At its place, 2. Order Gravel (7 to 50 mm diameter) can be used in train station tracks, but not in tracks on iron sleepers. For Tracks 3. Order, the need is usually to be covered by old bet fabrics; otherwise, track gravel is to be used.