Just curious as to the reason for the different types of type clamps as shown in the pics. Also it seems they often skip ties...with no pattern. And even then some railroads do not use them at all. Also, as a testament to Norfolk Southern track maintenance, the line in the photo is a very lightly used branch line. Recently upgraded to welded rail with "relay rail and ties." Looks better than some class 1 mainlines. Certainly better than many PanAm lines that see several large daily trains.