https://youtu.be/hs392e7z99Y The most useful and relevant information about building railroads is towards the middle of this video. China has standardized numerous parts and supplies for their railroad construction, such as tracks and embankments. This speeds up the ordering of components for bridges and lowers costs. Most supplies are locally sourced along the new routes which help local industry. Temporary factories along the route reduce transportation costs of the building components. Allegedly, no supplies need to be transported more than 8 kilometers (five miles). Viaduct designs are limited. Using numerous viaducts preserves farmland, cross rivers reduces the number of at grade crossings, and eliminates interference with other roads and highways. That grade seperation is what allows the trains to go high speed. Bridge beems for viaducts are either 24 meters (78 feet) or 32 meters 104 feet) long. No other choices are av...