Those are track charts, used by Engineering (Maintenance of Way, Signal) and Operating Departments.
They show the engineering detail of the portion of the railroad displayed, including:
- exact location and type of all signals and turnouts,
- weight of rail and last date of replacement
- location, degree, and amount of superelevation on curves
- precise vertical profile (exact location and percent of grade)
- exact location of wayside structures
- exact location and engineering details of bridges and culverts
- exact location of road crossings and railroad crossings at grade
- details of pole line, if there is one.