Fast overlays, zero ambiguity.
Overlays communicate design intent in a glance—if they’re legible. Set coordinate systems, layer/color conventions, and annotation rules for arrays, standoff, clear gaps, and utilities. Include QA checks and export settings so overlays drop straight into VDA reports and submissions, accelerating approval of HVM bollard proposals. Include one-sentence context that naturally links upward to the parent hubs (this section and the chapter hub). Add SIRA context with a link to SIRA Bollards (UAE) when relevant. Link installation pages only if helpful: What to Expect and Installation Guide.
Important: This is a general guide. For live projects we develop a tailored
Method Statement & Risk Assessment (MS/RA) and align with authority approvals (e.g., SIRA) where in scope.
936.1 Purpose & scope
Standardize overlays so reviewers see HVM bollard intent and crash rated bollard details at a glance (915, 717).
Overlays translate analysis into a single, readable layer: the Vehicle Dynamics Assessment (VDA) outputs, array locations, Stand-off distance, and utilities constraints. Scope covers linework, annotation, and packaging so anyone opening the file (CAD/PDF) can verify intent without guessing.
Overlay standards reduce rework in 915 — Drawing Sheet & Title Block Standards and speed authority review in 717 — Authority Submittals. Use this page with 931 — CAD/BIM Standards and 938 — Submission-Pack Guidance.
| Aspect | What matters | Where to verify |
|---|---|---|
| Performance | Tested system (bollard + footing) | Crash Ratings Explained |
| Operations | Duty cycles, fail-state, safety | Installation Guide |
936.2 Base plans & georeferencing
Use latest 931 sheets; lock scale, north, grids. Georeferencing avoids overlay drift in VDA/arrays (221, 321).
Start from the current title-block and sheet set in 931 — CAD/BIM Standards. Fix the drawing units and insert a north arrow, grid, and scale bar. When working from surveys/GIS, georeference the base to avoid misalignment with VDA traces and the array centreline.
Keep layer naming conventions consistent and bind only final xref bundles for submissions. For VDA overlays, cross-check 221 — VDA Method Overview and 321 — Array Patterns.
936.3 Symbols & colors
Approved icons for heads, gaps, loops, beams (313, 344–345). Color keys mirror 931 legends.
Use the symbol library: bollard heads (from 313 — Heads & Attachments), clear-gap tick marks, 344 — Induction Loops, and field devices per 345 — Field Devices. Match lineweights and colors to the 931 legend so overlays remain legible in print and on screens.
Reserve high-contrast colors for approach vectors, defend/penetration lines, and revision clouds. Add a small key on every overlay sheet to avoid ambiguity.
936.4 Standoff & vectors
Draw standoff rings and approach arrows with labels (213, 225). Evidence feeds selection (432).
Show the required stand-off distance as rings or bands around assets. Add labeled arrows for 225 — Impact Angles & Approach Vectors derived from 213 — Standoff & Protection Zones. Use consistent arrowheads and text height.
The vector diagram should support evidence-led selection in 432 — Design Selection Guide, showing the governing angle and credible worst-case runs used for tier/rating choice.
936.5 Clear-gap callouts
Dimension gaps with tolerance bands (232, 322). Note deflection/set references (314).
Dimension every clear-gap with a target plus tolerance band. Reference the spacing rules in 232 — Spacing Rules and calculation method in 322 — Clear-Gap Calculations.
Add notes for expected deflection versus permanent set using guidance from 314 — Deflection vs Permanent Set so reviewers understand post-impact serviceability.
936.6 Before/after comparisons
Split overlays for existing vs proposed. Aids HVM bollard stakeholder buy-in (845).
Provide side-by-side or stacked “Existing” and “Proposed” overlays with identical view extents. Use consistent scales, keys, and annotation so differences pop. Keep delta highlights minimal: defend line shift, added arrays, lane changes.
This visual makes stakeholder communication easier (see 845 — Stakeholder Communications) and de-risks late design churn.
936.7 Redline conventions
Cloud, note, and date changes; tie to 118. Redlines flow into 731 as-builts.
Use a single revision cloud style and layer. Every redline needs a delta note, author initials, and date. Summarize changes in the change log per 118 — Change Log.
On acceptance, publish a redlined drawing PDF and feed updates into 731 — As-Built Drawings & Models.
936.8 Evidence links
Embed photo IDs from 916 and filenames per 911. Traceable crash rated bollard records.
Where a note references site conditions or hazards, embed a hyperlink to the 916 — Evidence Capture Templates photo ID or to the file path named per 911 — File Index & Naming Rules. Include filename conventions in the overlay’s notes box.
For authority packages (UAE), add a short note linking to SIRA Bollards (UAE) indicating which sheets/photos underpin the submittal.
936.9 Export pack
PDF (vector), PNG (web), DWG with xrefs. Ready for 938 submissions.
Export three assets per view: (a) vector PDF (bookmarked and selectable text), (b) PNG/JPG for web decks, and (c) DWG with clean xrefs. Name files to match 911 rules and compile with 938 — Submission-Pack Guidance.
QA checklist before exporting: title/legend present, scale and north correct, keys visible, links resolvable, and no stray layers. Add a zip bundle recipe in the transmittal.
Related
External resources
- BSI: Vehicle Security Barriers — Impact Tests
- ASTM F2656: Crash Testing Overview
- NPSA: Hostile Vehicle Mitigation
936 Mark-Up & Overlay Standards — FAQ
What’s the fastest way to build a compliant overlay from scratch?
Start from the latest 931 title block, insert north/scale/grids, reference VDA traces, then apply the 936 symbol/color key. Add stand-off rings, approach vectors, and clear-gap callouts, finish with the export pack (PDF/PNG/DWG) per 938.
How do I avoid misalignment when combining GIS, survey, and CAD?
Georeference the base plan, lock units and rotation, and snap overlays to survey control. Exchange using clean xref bundles and verify against a control point before export.
Which items must be in every clear-gap annotation?
Target gap, tolerance band, reference to 232/322 rules, and a note on expected deflection/permanent set from 314 so reviewers can judge post-impact usability.
What should a UAE/SIRA submission overlay include?
Vector PDF with bookmarks, symbol/color key, stand-off and vectors, clear-gap callouts, and evidence links to photo IDs/named files (911/916). Include a brief note that maps sheets to the SIRA submission list.