Inconsistency between Existing Elevation from Cogo and Existing CL

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

Chainage Profile Elevaton Existing CL Elevation Report Difference
108700 14.142 14.146 -0.004
108710 14.114 14.115 -0.001
108720 14.103 14.102 0.001
108730 14.113 14.111 0.002
108740 14.136 14.134 0.002
108750 14.135 14.136

-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

Parents Reply
  •  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

    ?

Children