Likely vehicle threats, behaviors, and realistic worst-case framing.
Translate site context into defendable scenarios. Match vehicle classes and payloads with realistic run-up and angles, then apply sensitivity factors. This anchors whether an HVM bollard is required or a low-speed solution suffices (123, 434). Use helpers 922 and 225, record assumptions in 229, and carry results into ratings (411–416) and arrays/spacing (232, 321–325). 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.
212.1 Defining credible threats
Use site reality—access control, policing, approach speed (222)—to bound scenarios. If hostile intent is plausible, you’re in HVM bollard territory; certification decides if a crash rated bollard is mandatory (411, 717).
Start from the client’s Design Basis Threat (DBT) and observable cues (traffic patterns, barriers, enforcement). Record what makes a scenario credible (open approaches, limited supervision) and what lowers likelihood (strict access, police presence). When uncertainty is high, define a bounded “credible worst case” and flag it in your VDA report (229) for reviewer agreement.
If the DBT includes deliberate ramming, treat the solution as crash-rated unless a documented risk decision accepts low-speed protection. Cross-check with Selecting Low-Speed vs HVM (443) and ensure early reviewer buy-in (132).
| Aspect | What matters | Where to verify |
|---|---|---|
| Performance | Tested system (bollard + footing) | How to read ratings (413) |
| Operations | Duty cycles, fail-state, safety devices & measures | Installation Guide |
212.2 Vehicle types & payloads
Select representative masses/geometry (223). Payload adds energy and debris risk (412). Results drive HVM bollard tier (123) and the crash rated bollard rating line you’ll cite (413).
Use Vehicle Classes (223) to anchor inertial mass and geometry (SUV vs HGV). If a VBIED is in scope, note blast standoff needs may exceed vehicle-ramming controls; coordinate with façade/blast teams and document as a parallel control, not a substitute (213, 430).
212.3 Likely approach speeds
Estimate from run-up, friction, and bends (222, 227). Record ± bands (224.6). These set HVM bollard array density and the crash rated bollard speed class (413).
Use the VDA Approach-Speed Helper (922) with measured run-up distance, surface type, and curvature. Capture an acceptance band (e.g., 40–50 km/h) and hold that through the design so spacing (232) and patterning (321) don’t drift with every revision.
212.4 Single vs multi-hit
Assess queues and time gaps (226). Multi-hit may force tighter HVM bollard spacing (232) or heavier crash rated bollard selection and interlocks (342–345).
Where target density is high (e.g., event egress), model multi-hit credibility. Mitigations include staggered arrays (321), near-door tightening (323), and operational measures (temporary stewarded gaps). Note any system-level interlocks if automatic lanes are nearby (342–345).
212.5 Attack angles & vectors
Diagram worst-credible vectors on plans (225). Angle shifts penetration outcomes; set HVM bollard patterns accordingly (321–326). Verify crash rated bollard orientation limits (413, 421).
Mark each approach vector and its feasible angle. Oblique impacts often increase penetration; select patterns (e.g., chicanes, 324) that break alignment. If the certificate notes orientation dependencies (421), mirror the as-tested setup in layouts and call this out in the submittal (938).
212.6 Crowd proximity & timing
Weight scenarios by peak footfall and events (231, 239). Closer crowds justify higher HVM bollard tiers; a crash rated bollard near doors needs height/offset checks (312, 323).
Map footfall by hour and event calendar. Where frontage queues form, consider door protection arrays (323) and ensure effective height (312) is not compromised by steps/ramps or finishes.
212.7 Sensitivity factors
Apply conservative allowances for speed/angle/mass (228). Document tables that explain HVM bollard decisions and any crash rated bollard equivalence claims (414).
Run a brief sensitivity analysis around your inputs; if results straddle rating lines, justify with a stated safety factor and reference standard language on equivalencies (414). Keep the table in your VDA pack (229) for reviewers.
212.8 Scenario selection matrix
Score credibility vs consequence; pick design cases. Link each to HVM bollard array options (321) and a candidate crash rated bollard rating (413).
Use a 2×2 matrix (Low/High credibility vs Low/High consequence). Select one “governing” and one “check” case. For each, list speed band, vehicle class, angle, crowd proximity, and proposed pattern (e.g., Array Patterns, 321). Tie each case to a candidate rating string (413) you’ll verify against certificates (431).
212.9 Documenting assumptions
State sources, dates, and uncertainties (229). Good notes shorten HVM bollard reviews and stabilize crash rated bollard approvals (444, 938).
Record site visits, speed measurements, CCTV samples, and stakeholder inputs with dates and filenames per File Index & Naming Rules (911). Keep a short “assumptions & open points” list in the VDA report (229) and carry it into the submission index (938) so reviewers see provenance and limits.
Related
External resources
- NPSA: Hostile Vehicle Mitigation (threat-led design)
- ASTM F2656: Vehicle impact testing
- IWA 14-1 (BSI): Impact test specifications
212 Threat Scenarios — FAQ
What’s the difference between a “credible” and a “worst imaginable” threat?
A credible threat is grounded in site realities (access, run-up, policing, crowd timing) and recorded as the DBT. The “worst imaginable” is unconstrained and unhelpful; it inflates costs without improving outcomes.
When do we need crash-rated bollards rather than low-speed protection?
Use crash-rated products when deliberate ramming is plausible or approach speeds exceed low-speed test regimes. Cross-check with Selecting Low-Speed vs HVM (443) and confirm with reviewers early (132).
How do attack angles change penetration and layout?
Oblique angles can increase penetration even at the same speed. Use chicanes or staggered patterns (321, 324) and respect any orientation notes in certificates (421).
What should be kept in the VDA report for reviewer acceptance?
Inputs, ranges, and why they were chosen; sensitivity tables; selected design cases; drawings of approach vectors; and a clear link to the rating string (413). File it using the naming rules (911) and list in the submission index (938).