Combining fixed, removable, and automatic coherently.
Mixing fixed, removable, and automatic units can cut cost and improve flow—if the logic is clear. Harmonize heights and finishes (312, 316) and capture control/override implications (342–355). Plan maintenance access and spares (365, 842). Acceptance testing must confirm clear gaps and fail-states across combinations (232, 355, 636–638). Link product family variants and limits to certificates (415, 421). 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.
326.1 When to mix types
Mix fixed, removable, and automatic to cut cost and improve flow (338). Keep logic clear and gaps consistent (232). Ensure each crash rated bollard variant is approved within the same family (415).
Use mixed arrays when you need frequent vehicle access at a portal but permanent protection along long frontages. Define “why each unit exists” in a short rationale: throughput target, clear-gap control, blue-light entry, or rare maintenance access. Keep a single rating across the line or deliberately step up (never down) toward the portal. Where rare access is sufficient, prefer passive removable units over additional automatics.
Document the chosen mix in drawings and in the specification: rating string, as-tested configuration, foundation class, and acceptable alternatives. Cross-reference product families & variants (415) to prevent incompatible substitutions.
| 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 |
326.2 Fixed + automatic combos
Place automatic units at portals; fill flanks with fixed posts. HVM bollard rhythm stays readable (316). Automatic crash rated bollard models must match the fixed unit’s rating or exceed it.
At portals, use an automatic lane set sized from the spacing rules (232) and modes of operation (525). Flanks continue with fixed posts of the same certificate scope. Keep the array’s visual rhythm legible using consistent centres and sleeve styles (316). If the automatic relies on a different foundation type, ensure transitions don’t create weak points at joints or utility crossings (332–333).
Where sightlines or queue management matter, add signage & markings (357) and a pattern that discourages human shortcuts without creating handlebar traps.
326.3 Removable inserts
Provide inserts for rare access (233). Keepered covers protect geometry. The removable crash rated bollard insert must reseat within tolerance (626).
Use lift-out sockets with keepered openings so surface levels and edges remain controlled when the post is out. Specify cover loading class, slip-resistance, and a tether to prevent loss. Define reseating tolerances and inspection steps in datum & alignment checks (626).
For portals that need planned occasional access (e.g., facade glazing changes), removable posts can replace a second automatic lane. However, ensure stewarded procedures (authorised keys, PTW) and a recorded reset-to-normal checklist after works.
326.4 Height variations
Blend heights to deter climb while preserving sightlines (312, 237). HVM bollard low-high patterns still meet effective gap rules. Pick crash rated bollard heights from the same certificate set (415).
Minor height staggering can improve climb deterrence and readability at distance, but never break the effective gap and effective height (312) requirements. Check that every chosen height exists within the product’s certified variants; mixing custom sleeves that exceed certificate bounds risks an out-of-scope configuration (421).
326.5 Finish harmonization
Match sleeves/colors across types (366). Harmonization prevents ad-hoc looks and preserves HVM bollard legibility; coating systems remain within crash rated bollard allowances (362, 421).
Specify a single sleeve family and colourways across fixed, removable, and automatic models to keep wayfinding and streetscape integration (238) consistent. Confirm the sleeve material and coating stack match the tested rating-critical dependencies. In coastal exposure, consider duplex coating (362) or 316 stainless, and record maintenance intervals in the preventive maintenance plan (734).
326.6 Control logic implications
Define modes and permissions for automatics (525). HVM bollard states are consistent; ensure fail states keep a crash rated bollard perimeter closed (355).
Align the automatic lane’s modes of operation (525) and interlock matrix (352) with adjacent passive lines. In fault, power-loss, or EFO (354), the perimeter should stay closed or be recoverable without widening the clear-gap. Add clear portal language on credentialed access, latched/manual releases, and stewarded emergency overrides.
326.7 Maintenance complexity
Mixed spares and skills raise OPEX. Standardize where possible (365, 842). Keep crash rated bollard spare parts common across types.
Each added type multiplies training, parts, and downtime risk. Prefer one vendor family so pumps, seals, power modules, and electrical protection share parts. Record common spares, recommended quantities, and response SLAs in the project’s service levels & availability (738). Use an ops dashboard to track cycles and plan preventive maintenance across the mixed set.
326.8 Acceptance testing
Prove gaps and fail-states across combinations (634–638). HVM bollard arrays pass gauge checks; automatic crash rated bollard units meet cycle/EFO targets (354, 636).
Build test cases that traverse the whole mix: portal closed, portal open, removable out (with keeper in place), degraded states. Verify with a calibrated Go/No-Go gauge and record results in the interlock verification (634), performance & duty tests (636), and SAT witness procedure (638). For UAE projects, note SIRA witness/approval steps where in scope and reference SIRA Bollards (UAE).
326.9 Example layouts
Show portal + flanks, frontage mixed, and island mix. Indicate HVM bollard centers and the crash rated bollard models used (413, 415).
(a) Portal + flanks: Automatic lane set at the entrance with fixed arrays left/right on consistent centres. Label centres, footings, and product codes. (b) Frontage mixed: Fixed line with a removable keepered bay at a service door; add a stewarded reset checklist. (c) Island mix: Staggered island cluster with fixed posts and one automatic lane; keep pattern readable and verify clear-gaps per calculation (322).
Related
External resources
- NPSA: Hostile Vehicle Mitigation (Guidance)
- BSI: Impact test specifications for VSB systems
- ASTM F2656: Crash Testing Standard (Overview)
326 Mixed-Type Arrays — FAQ
Do mixed arrays weaken security compared to a single type?
No—provided all units share an equal or higher crash rating, maintain the certified as-tested configuration, and keep effective clear-gaps per the spacing rules. Use an interlock matrix so automatic lanes never create an unguarded opening during faults or overrides.
How do I stop substitutions that break certification?
Lock the specification to a tested product family and list allowed variants with model codes. Cite the rating-critical dependencies (foundation class, sleeve, height) and include an anti-downgrade/equivalence clause that requires evidence before any change.
When should I choose removable posts over another automatic lane?
Use removable (lift-out) posts for rare, planned access where stewarding is feasible. They reduce cost and complexity but require keepered openings, a reseating tolerance check, and a reset-to-normal checklist to eliminate gap drift.
What extra tests are needed at SAT for mixed arrays?
Add combined scenarios: portal closed/open, removable out/in, and degraded states. Gauge the clear-gap, verify fail-safe/secure behaviour, run duty/EFO cycles on automatics, and record evidence in the Interlock Verification, Performance & Duty Tests, and the SAT witness pack.