Acu_Calc Terminology

Acu_Calc uses the following terms and definitions. For graphical information, follow the links to the diagrams. The information shown in between [ and ] describes the constraints in type and value for each input to Acu_Calc.

ACI File: the entire set of input values and optional descriptions. Use the Open command button to access an existing ACI file.
Criteria: the set of values for complying with the reference document (IES RP-8-14 only, at present) for the selected roadway classification e.g. Collector High, part of the input file.
Description: optional text for describing file, luminaire, geometry or roadway input data.
Geometry: is the part of the ACI file that describes the pattern of luminaire locations described by the layout, spacing, mounting height and overhang(s).
IES_directory: is the name of a sub-directory with photometric data in IES format. The selection is limited to the subdirectories of the client photometric directory. When the calculations are run, all the photometric files in the subdirectory are included.
#Lanes: number of lanes in the travelled way [integer, greater than 0]. Each lane has equal width.
Layout: one of the defined patterns of luminaires along the roadway [L, R, O, or S], called Left, Right, Opposite and Staggered. When the median is greater than zero, every layout is expanded to include luminaires located on the other side of the median. (also see Overhang and OverMedian.)
Left: the layout with luminaires only on the left-hand-side of the roadway. See the layout for left side in this diagram and the diagram with a median.
LLF: the light loss factor (LLF) for the luminaires [real, greater than 0.01 up to 1.0]. This value should reflect the worst-case situation over the maintenance cycle. The LLF link on the Acu_Calc form leads to the MDI LLF Calculator.
Longitudinal: the direction along the the roadway, in the direction of travel, compare with transverse.
Luminaires: is the part of the ACI file with information concerning the light sources, described by the photometric file, along with the rated lumens and the LLF, and located as defined in the geometry.
Median: the distance from the left-hand edge of one traveled wy to the other [real, greater than 0, default = 0]. When the median is greater than zero, there are additional lanes included on "the other side" of the median, and additional luminaires included in the calculation, following the specified layout.
Mounting Ht: the vertical distance from the roadway up to the luminaire.
Opposite: the layout with luminaires directly across the roadway from each other. See the layout for opposite in this diagram and the diagram with a median.
Overhang: the transverse distance from the edge of and in towards the roadway [real, any value], negative values correspond to setback.
OverMedian: is the overhang distance from the edge of a median (and then overhang applies to any luminaires on the outside of the roadway).
Output: is the results from the calculation, with choices for numerical or graphical information. The Values link opens a new window to display all output corresponding to the currently selected ACI File. At the top is the numerical summary reporting the inputs used and the results as they compare to the RP-8-14 criteria.
#Points Along: number of calculation points along the roadway in one spacing [integer, from 10 up]. This is the minimum number of points along each of the two longitudinal lines in each lane. There must be at least 10 points and they must not be more than 5 meters apart (these conditions are met automatically by Acu_Calc).
Right: the layout with luminaires only on the right-hand-side of the roadway. See the layout for right side in this diagram and the diagram with a median.
R-Table: refers to the roadway surface definition per RP-8 as one of four defined types [R1, R2, R3, R4]. R1 is considered representative of concrete surfaces while R3 is the typical for asphalt/blacktop, and considered the default.
Roadway: is the part of the ACI file that defines the grid of calculation points representing the traveled way, comprised of a number of lanes of equal width, with a horizontal surface described by a R-table. This does not include any shoulders, breakdown lanes or other paved areas outside the traveled way.
Setback: the transverse distance, measured from the edge of the roadway and away from it, appplied in Acu_Calc as negative values [real, less than 0] for overhang.
Spacing: the longitudinal distance between luminaire locations [real, greater than 0]. See layout and corresponding diagrams.
Staggered: the layout with luminaires alternately across the roadway. See the layout for staggered in this diagram and the diagram with a median.
Transverse: the direction across the roadway, perpendicular to the direction of travel, compare with longitudinal.
Units: the units used for all dimension in the input file: Feet or Meters [F or M].
Values: is the link to show numerical output from the calculation as a text file. The link opens a new window to display all output corresponding to the currently selected ACI File. To save the output file to a local device, use the browser's File/SaveAs command.
Width: the transverse dimension of one lane [real, greater than 0], where each lane has the same width.