I am having a little trouble understanding the way the Arc vs Chord definition setting should work during the use of the Spiral Curve Spiral tool. Below I have 2 scenarios that report different results. I would like to know why this is happening and if there is a fix.
1. Create a Spiral Curve Spiral (SCS) between 2 tangents that are Civil elements or have Civil rules.
a. Settings->Design File-> Civil Formatting->Radius Settings - Arc Definition, 100' arc, and character set to "d"
Degree of Curvature, D = 10°.
Degree of Curvature; Arc Definition, R = 5729.578/D = 5729.578/10 = 572.9578
Invoking the SCS tool it is possible to use either value D or R within the tool to place the element into the drawing. The appropriate data is noted in the Horizontal report for the Arc definition.
b. Settings->Design File-> Civil Formatting->Radius Settings - Chord Definition, 100' arc, and character set to "d"
Degree of Curvature, D = 10°
Degree of Curvature; Chord Definition, R = 50 / (sin(D/2)) = 50 / (sin(10/2)) = 573.6857
Invoking the SCS tool for D = 10, R = 573.6857 only the R value can be entered to develop the element into the drawing. When the character "d" is used and 10 is entered for the degree of curvature the tool returns an error. When the chord definition calculated R value is entered into the spiral-curve-spiral tool, the element will be placed within the drawing.
After the element is placed into the drawing using the Chord definition, the Horizontal report displays the degree of curvature as 9° 59' 14.32". By definition it is known that the Degree of Curvature is 10° but the report is using the R value as determined by the chord definition and reporting the Degree of Curvature using the Arc definition formula. The reported value is developed as such, D = 5729.578/R = 5729.578/573.6857 = 9.987311868 decimal degrees or 9° 59' 14.32"
2 part question-
1. Why can I not enter the D value when the radius setting is set to Chord definition? Or am I missing something?
a. If the D value cannot be used with the Chord definition then how can I change the Horizontal report style sheet so that the report calculates the D value as a chord value and not the arc value?
TIA
Sean
MSV8i - 08.11.09.608 & 08.11.09.654
OpenRoads - 08.11.09.722 & 08.11.09.788
It seems you should be able to use the Degree of Curve method for either the Arc Definition or Chord Definition geometry and the report should indicate the method used to calculate the Degree of curve. If I generate geometry in SS2 InRoads creating one horizontal geometry using Arch and one using Chord both with the radius calculated using a D=10 the geometry reports seem to work fine. However if I then import the same geometry into OpenRoads graphical geometry the report only calculates the Degree of curve using the Arch formula. See reports below.
InRoads SS2 Geometry report
Radius: 573.6857Delta: 45^00'00.0000" RightDegree of Curvature(Chord): 10^00'00.0000"
Radius: 572.9578Delta: 45^00'00.0000" RightDegree of Curvature(Arc): 10^00'00.0000"
***************************************************OpenRoads Geometry report
Radius: 572.957795 Delta: 45.000000 Right Degree of Curvature (Arc): 10.000000
Radius: 573.685662 Delta: 45.000000 Right Degree of Curvature (Arc): 9.987312
If you change the design file setting for Degree of Curve Method from Arc to Chord the report then indicates that the Degree of curve method is Chord, but still uses the Arch method to calculate and report the DOC, as seen below and above, where the DOC of Arc and the DOC of Chord for a Radius of (573.685662) are shown to be the same value (9.987312).
Radius: 573.685662 Delta: 45.000000 Right Degree of Curvature (Chord): 9.987312
Mike LongstreetVermont Agency of TransportationCivil Engineering Technical SupportVTCAD Help
For more information about the Road and Site design tools, visit the Road and Site design WIKI at: http://communities.bentley.com/products/road___site_design/w/road_and_site_design__wiki
I see that in the latest version of OpenRoads this defect is one of the Horizontal Geometry Enhancements. I can verify that it is calculating the curves based upon degree of curve(DOC) definition but the results do not match the OpenRoads Help file on DOC definition of arcs. Specifically under Civil Geometry->Getting Started->Civil Geometry Degree of Curve states that you can enter DOC definition by entering d followed by the DOC and the heads up prompt will show the DOC. Also once the curve is placed once you select the curve the DOC should show up in the manipulators.
From my experience this is not working.
Step 1 - Establish tangents and then create curve between tangents by using DOC.
Step 2 - Accept DOC entry but Radius is shown in heads up dialog
Step 3 - After placing arc manipulator shows radius not DOC
Please let me know if this is still a defect or it should have been fixed with the recent release.
MSV8i - 08.11.09.714
OpenRoads (Geopak flavor) - 08.11.09.845