Railroading is not usually mentioned in home decor books. However, knowing what it is and how to use it effectively can save you both time and money.
Railroading is an optional cutting layout. Basically, the lengthwise fabric grain (threads that are parallel to the selvage) will run horizontally on the finished project (as along the hemmed edge of a valance). This means that the cut project width is one continuous fabric length, cutting down on seams and eliminating the need to match patterns.
Railroading is ideal for sheer fabric projects in which seams would be visible. Railroading is often used for valances, dust ruffles, sill- or apron-length curtains, or any other project where the cut length (the vertical length plus any allowances for hems or seams) is 54″ or less.
Many fabrics can be railroaded, but examine the fabric closely to determine if the design can be turned sideways. For example, flowers with stems, or other obvious one-way designs (with the exception of stripes) can’t be turned sideways. Allover prints or geometric designs such as circles, dashes and squares can all be successfully railroaded. Remember that if you railroad striped fabric, the stripes will be horizontal on the project.
Yardages are calculated differently when fabric is railroaded. To determine the amount of fabric needed, divide the cut width (as opposed to the length) by 36″.