Sentence:  If you are upholstering a larger item, such as a sofa, it's a good idea to see if the fabric you are buying can be <WSD>railroaded</WSD>. <WSD>Railroading</WSD> refers to being able to run the fabric from left to right, rather than the conventional top to bottom. ...[W]hen a pattern is <WSD>railroaded</WSD> you can turn it on its side and roll it out to the width of the sofa without join lines. 
Meaning of the word marked with <WSD> tags:  To run fabric horizontally instead of the usual vertically.