MARKING MATERIALS

generally marked with permanent markers. These markers could be in the following forms: . A bronze disk set in concrete l An iron pipe filled with concrete . A crosscut on an existing concrete structure or on a rock outcrop . A hole drilled in concrete and filled with lead or a metal rod driven into the ground with a center-punched mark to designate the exact point All permanent survey station markers should be referenced so they can be replaced if disturbed. Methods of referencing points are discussed later in this training manual. Surveyor’s tacks, spikes, and nails are often driven into growing trees, bituminous, or other semisolid surfaces as permanent markers. A nail will be more conspicuous if it is driven through a bottle cap, a washer, a plastic tape, or a “shiner.” A shiner is a thin metal disk much like the top or bottom of a frozen fruit juice can. A SPAD is a nail equipped with a hook for suspending a plumb bob. It is driven into an overhead surface, such as the top of a tunnel. The plumb bob will locate on the floor the point vertically below the point where the spad is driven. Points on concrete or stone surfaces are often marked with an X cut with a hammer and chisel. Another way to do this is to cut holes with a star drill and then plug them with lead. A much more durable form of marker is made of a length of metal pipe—usually called iron pipe regardless of the actual metal used. Lengths run from about 18 to 24 in. Sawed-off lengths of pipe have open ends; pipes cut with a shear have pinched ends and are called pinch pipe. There are also manufactured pipe markers, some of which are T-shaped rather than cylindrical in cross section. A commercial marker may consist of a copper-plated steel rod. All commercial markers have caps or heads that permit center punching for precise point location and stamping of the identifying information. A still more durable form of marker is the concrete monument. A short length of brass rod is often set in the concrete to mark the exact location of the point. Concrete monuments that are used as permanent markers by various federal survey agencies have identifying disks set in concrete, like those shown in figure 11-57. Figure 11-57.-Various types of federal marking disks. Points on concrete or masonry surfaces may be permanently marked by setting lengths of cylindrical brass stock into holes plugged with lead or grout. Brass stock markers set in pavement are commonly called coppers. Manufactured brass disks, similar to the ones shown in figure 11-57, may be set in grouted holes in street pavements, sidewalks, steps, or the tops of retaining walls. Points on bituminous surfaces maybe marked by driving in pipe, railroad spikes, or case-hardened masonry nails, commonly called PK nails. A center punch for marking a precise location on metal stock or metal caps is a common item of equipment for a surveyor. MARKING MATERIALS KEEL, or LUMBER CRAYON, is a thick crayon used for marking stakes or other surfaces. Common marking devices that contain a quick- drying fluid and a felt tip are also popular for marking stakes. All of these types of graphic marking materials come in various colors. In addition to keel, paint is used to mark pavement surfaces. Paint may be brushed on or sprayed from a spray can. To make the location of a point conspicuous, use a circle, a cross, or a triangle. Identification symbols, such as station 11-48