321.1 Inline vs staggered

Inline arrays are simple to set out and read, but glancing vectors can slip through. Staggered HVM bollard layouts shorten effective clear gaps (232) and deflect approach lines (214). Check that your crash rated bollard family permits mixed centers and orientations (415, 421).

Inline rows are fast to set out and easy for the public to understand, but they can leave longer clear-gaps along shallow angles of approach. In busy frontages with diagonal approach vectors, staggering shortens the effective opening and nudges hostile paths away from sensitive doors.

When staggering, confirm your product’s orientation dependency and ensure the certification’s “as-tested” centers match your intended offsets. If mixed centers are allowed, record the chosen rating string on drawings and in the specification.

Practically, staggered rows need tighter datums to prevent gap drift. Plan checking points in the ITP so installers prove centerlines and heights before concrete pour.

321.2 Islands & clusters

Island clusters disrupt run-up and create pedestrian refuges. Use where width is generous (231). HVM bollard islands need drainage routes (245). Corner islands often host a corner crash rated bollard with tighter gap control (324, 314).

Clusters break up run-up distance and form refuge pockets around busy doors. Prioritize generous pedestrian desire lines and protect corners where glancing impacts are credible.

Drain trapped surfaces: include falls to a sump (see drainage strategy) and avoid ponding near service lids. Where islands touch curb returns, consider the corner throat and maintain emergency widths.

Corner islands often justify one higher-tier unit at the apex tied to the site’s governing angle. Capture these decisions in the VDA and drawings.

321.3 Horseshoe & U-shapes

U-shapes protect recessed doors and loading pockets (234). Keep outer legs aligned to vector bands (225). HVM bollard legs must retain compliant gaps; the head unit can be a higher-tier crash rated bollard if risk concentrates there (235).

Use a U when a recessed doorway, loading pocket, or glazing bay creates a natural pocket. Align both legs with dominant approach corridors and keep the “mouth” narrow enough that the effective effective width respects the clear-gap rule.

At the base of the U, specify the apex unit to match the highest-risk scenario from the Purpose/Tier Matrix. Confirm the product’s certificate scope covers the U arrangement and orientations.

321.4 Perimeter lines

Long frontages suit continuous lines with rhythm (316). Insert periodic keepered openings for service (233). Choose a crash rated bollard model with compatible foundations along variable soils (332–333, 423).

On long façades, continuity improves legibility and reduces enforcement burden. Plan keepered openings for deliveries and align them with safe stopping space. Keep a consistent visual rhythm so routes remain intuitive.

Varying substrates demand early coordination with foundation types and groundwater risks (soil effects). Where services are dense, assess shallow options and record any constraints in the VDA.

321.5 Pinch points & chicanes

Chicanes force path changes and reduce speed (227). Stagger HVM bollard posts so emergency widths remain (233). Use a crash rated bollard at the chicane nose to take first impact risk.

Pinch points and gentle “S” bends reduce approach speed without blocking blue-light access. Place the strongest unit at the nose where an errant vehicle would first strike and verify stopping sight distance remains adequate.

Coordinate signage and sightlines, and keep pedestrian flows readable with clear contrast bands on paving. If a stewarded gap is planned for events, add a reset checklist in the ops pack.

321.6 Temporary add-ons

Plan sockets or sleeves for event-day posts (239, 327). Temporary HVM bollard elements must not widen permanent gaps (232). Do not claim a temporary item as a certified crash rated bollard.

Pre-place sleeves or plates for event modes so set-up is quick and repeatable. Make sure temporary pieces never degrade the certified arrangement’s as-tested configuration. Label storage and include a reset-to-normal checklist.

321.7 Pattern selection rules

Start from VDA vectors/standoff (221, 213). Pick the fewest posts that achieve pass/fail. Confirm the crash rated bollard certificate orientation matches the chosen pattern (413, 421).

Begin with the VDA method: map vectors, set stand-off, and define a credible worst case. Then choose the simplest array that achieves the pass, accounting for deflection and permanent set.

Cross-check that product orientation, spacing, and footing class are within the certificate’s limits. Where mixed variants are used (e.g., heavier unit at a nose), record it clearly in the specification and drawings.

321.8 Examples with pros/cons

Provide inline (fast install), staggered (better angles), island (refuge), and U (recess cover) diagrams. For each, list HVM bollard gap math (322) and the crash rated bollard variant used (415).

Inline: quickest to set out; weakest against shallow angles. Staggered: better against glancing routes; needs tighter tolerances. Island/cluster: breaks run-up; needs drainage and careful pedestrian routing. U-shape: ideal for recesses; confirm orientation and apex strength.

For each diagram, show the clear-gap calculation (see Clear-Gap Calculations) and call up the exact product family/variant used.

321.9 Documentation standards

Dimension centers, offsets, and gauges on CAD (931). Add acceptance tags for HVM bollard gaps (626) and embed the crash rated bollard rating string on drawings (413).

On sheets, embed the rating string next to the defend line, show keepered dimensions for openings, and add an inspection band with the required checks. Tie acceptance to a Go/No-Go gauge and have photos logged to the redline book.

Array Patterns — FAQ