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Road QC

Audits selected road alignments and their finished-ground profiles against design-speed-keyed geometric standards: min curve radius, min/max grade, crest/sag K, vertical-curve length, and grade breaks, then flags each failing station red (error) or orange (warning).

Command VDCROADQC · VDC QC tab › Design QC panel
Audits selected road alignments and their finished-ground profiles against design-speed-keyed geometric standards: min curve radius, min/max grade, crest/sag K, vertical-curve length, and grade breaks, then flags each failing station red (error) or orange (warning).
Reads each alignment's design speed + FG profile, checks radius / grade / K / VC vs the preset. PLAN, horizontal alignment R = 240' ERROR: R < min radius @ 35 mph PROFILE, finished-ground crest VC, K = L ÷ Δg ERROR: crest K < SSD min +2.4% −3.1% WARN: 0.30% < 0.70% drainage min (private) MText flag @ station layer 0-NPLT
Horizontal alignment   FG profile   Error flag   Warning flag   Measurement guide

What it checks

  • Design speed: reads each alignment's speed, looks up the AASHTO-keyed row (highest at or below the speed) for radius / K / VC-length minimums.
  • Radius: each simple horizontal arc vs the min radius for that speed (error).
  • Grade: each profile tangent vs min drainage grade (private 0.70% / public 0.80%) and the max grade (errors).
  • Crest / sag K: K = length ÷ algebraic grade change vs the SSD minimum (error).
  • VC length vs the speed minimum, and grade breaks with no VC (warnings; Private tolerates up to 3%, Public 1%).
  • Threshold 0 or a code in DisabledChecks skips that check; a 0.005 display-rounding tolerance prevents at-minimum false flags.

Modes & output

  • Run audits + places flags; Clear wipes them.
  • Flags = red/orange MText at the offending station on 0-NPLT (auto-created); re-running wipes and re-places.
  • Findings palette (shared with VDCLOTQC / VDCPIPEQC): severity, station, check, message, double-click a row to zoom.
  • Appends to per-folder VDC-QC-LOG.txt and stamps VDC_QC_STATUS (read by VDCQCSTATUS).
  • Settings VDC_ROADQC_SETTINGS; standards VDC_ROADQC_PRESETS, point workstations at one shared presets file.
  • v1 scope: simple arcs + symmetric parabolic VCs only; one representative design speed per alignment.

Dialog

Road QC dialog
Road QC, VDCROADQC
Settings file: %APPDATA%\VDC\RoadQC\settings.json  |  %APPDATA%\VDC\RoadQC\presets.json

When to use it

  • QC of road geometry and profiles against the design speed.

How to run it

  1. Run VDCROADQC and pick the design-speed preset.
  2. Select the alignment(s) and profile(s) to audit.
  3. Review findings; double-click to zoom.

Watch out for

  • Grade display tolerance matters - very small grades near the minimum can read as false flags if values are rounded.
  • Confirm public vs private so the right minimum slope applies.

Related: Pipe QC · QC Status