All
Am experiencing some inconsistencies when showing existing elevations in profile annotation. Workflow is as follows
Import survey line strings for RH and LH rail
Create Existing CL Alignment from RH and LH using regression tools.
Create Cogo Points from Existing CL using Event Point tools - Alignment Points to Cogo
In new Alignment, design Horizontal, Vertical and Cant alignment and create design profile
Annotate design profile using existing elevation from regression points at 10m interval.
My issue comes from when I compare the profile annotations of my regression/cogo points elevations to a Station Base report of the Existing CL Alignment elevations. There is a difference, up to a maximum of about 5mm between the report and what is shown on the profile annotation. See table of results comparing and image showing Report and profile annotation
-0.001
Why is this happening? 5mm is not a small number by rail standards and this has the potential to intrduce errors in my design. Would appreciate any help
Thanks
A
Hi Alastair,
If you create a list report of your cogo-points, would they be at exact the same chainage (i.e. rounded at 10 m)? In "Profile Annotation" you can choose to show the vertical slews at an interval (f.ex. every 10 m) or the exact chainage the cogo-points are.
Regards, LiPeng
My cogo points are not recorded at exact chainage points. They are surveyed points approximately every 5m, so they will be at chainage/station 108701.475 for example.
My current set up is to do as you say - and Compute elevations from regression (cogo) points at a 10m interal as per this image. However the annotations are not the same as the report still
I think the issue comes from the report. You do the report based on EH_P2_ROAD which is the existing. But if you annotate the design profile you are based on the design alignment. You should do a station base report with the design alignment in the "From Alignment" and the existing alignment in the "Include alignment".
jpln the report is used to verify the existing alignment points.
EH_P2_Road is the existing CL of Platform 2 Track from survey. I use the cardinal points of this alignment (linestring at approx 5m centres) as the Cogo points of the design alignment.
Therefore I think that the report for elevation of EH_P2_Road should report the same elevation as the Existing" row that is annotated on the design vertical profile
but it does not
?
if You annotate at interval on the design profile, the stationing of the design alignment is used and elevation interpolated. But on your report you only use existing. So you don't use the same reference. You may have a slight difference between design and existing alignments