Up until the late 1940's early 1950's most Logging rail grade and road grade were built by "Cable Grade Shovels" , as the "Bulldozer" was developed , it became more popular for use in building Logging road grade . By the mid 1950's Cats were the preferred machine for building Logging road grade . By the early 1960's Cable Grade Shovels were fazed out . This statement refers to the Port Renfrew area I grew up in . There is terrain on the West Coast of British Columbia that Grade Shovels out perform Cats , I know of Grade Shovels building Logging roads up until the late 1970's . As the Hydraulic Excavator was prefected , it replaced both Cats and Grade Shovels for building logging roads . The "Arch built on the back of the Cat showed up in the late 1950's or early 1960's , it was great for "Cat Logging" or for pulling logs off the right away before the Grade was built . The Cat in the picture was probably kept around to spread ballast on new Logging roads or to do chores like cleaning debris off roads and landings .