Vertical Curve Programs for the HP-48
1996 Ted Cashin (Internet: dtbrejc@dot.state.ga.us)

The programs NEW, OPEN, and SAVE are utilities that work just like the File menu commands in a real computer program.

NEW is a program which prompts the user for input data so that the programs ELEV, SLOPE, and LOWPT can work.

SAVE allows the user to save this input data in a file (list variable) whose name the user can type in at the appropriate prompt.  This file will be stored in a subdirectory called DATA.  If name typed in is the same as an existing variable in DATA or HOME, program will confirm that you want to overwrite the file. You can not overwrite a non-list variable (i.e. a program or number). This was done because when SAVE looks for an existing file it looks in the HOME directory as well as the DATA directory so you could accidently overwrite numbers or programs in HOME.

OPEN allows the user to take an existing data file from DATA and place the values in the variables of VCURV without reentering the data.  This is very useful when you are dealing with multiple bridges or a bridge with more than one vertical curve.  To open a file just press the OPEN key and you will see a list of files available.  Press the appropriate key or NXT to see the next screen of choices.

ELEV takes a station on the stack and returns an elevation.  If the station is not on the vertical curve, the program assumes an elevation is desired on the tangent, but alerts the user to this by telling him whether the station is before the PVC or after the PVT.

SLOPE does the same thing as ELEV but gives slope at the station in question.

LOWPT gives the station and elevation of the low point of a sag curve, the high point of a crest curve, or will tell the user that the grades have the same sign (which means there is no high or low point).  LOWPT uses ELEV to find the elevation after it finds the station of the point in question.

The user can change values of G1, G2, L, PVI, or EL to run other sets of data without going through VCURV again.