312.1 Minimum effective heights

Set head heights to intercept vehicle structures, not just bumpers. Correct height preserves HVM bollard gap performance and honors the crash rated bollard test geometry (413, 421).

“Effective height” is the portion of the bollard that will engage a vehicle’s chassis or load bed. For cars and light vans, this means ensuring the head elevation catches above the decorative bumper fascia; for goods vehicles, target the load-platform leading edge. Use the product’s crash test report (413) to confirm the as-tested head height and keep site variants within its acceptance band (421).

When arrays include mixed heights, verify that the lowest element still maintains the certified penetration distance under worst-case approach vectors (225). If in doubt, raise the nominal head by a small increment rather than widening spacing; height protects gaps without increasing pedestrian pinch risk (232, 324).

312.2 ADA/clearance implications

Meet accessibility clearances around heads and rails (231). Accessibility and safety can coexist if HVM bollard heights don’t encroach; keep a crash rated bollard sleeve edge smooth (366).

Heights must not create trip or cane hazards. Maintain consistent head elevations so the effective width of pedestrian routes meets local code, and avoid intermediate rails unless required by the design brief. Where rails are used, set the underside to clear mobility device footrests while keeping the top rail below chest level for standing users (231, 237).

Edge treatments matter. A smooth sleeve with a slight radius reduces snagging, and a subtle contrast band at typical eye-down angles aids wayfinding without changing height. Coordinate with People flow & egress widths (231).

312.3 Slope & finished level effects

On slopes, effective height changes with grade. Adjust nominal height to keep HVM bollard performance and the crash rated bollard’s tested envelope (232, 314).

On longitudinal grades, bollards uphill read taller and downhill shorter relative to the vehicle datum. Model a simple section: take the design grade, proposed head elevation, and check the lowest head vs. the certified envelope (314). Where crossfall or camber exists, assess at curb-line and carriageway positions—approach height can differ by several centimetres.

To preserve clear gaps (232) while correcting height, prefer small plinths or shimmed sleeves over changing footing depth late in the program. Document any adjustment on the CAD/BIM standard sheets (931) so the SAT team can verify as built (632–636).

312.4 Head shape vs height

Domed/flat heads influence climb and visibility (313, 237). Pick shapes that aid HVM bollard function; ensure the crash rated bollard variant is approved (415).

A flat head maximizes visible plane and makes level checks easy, but can encourage sitting/climbing if set too low. A shallow dome sheds water and discourages standing; however, domes can appear “shorter” from distance, so pair with reflective edges or a narrow contrast ring (237). Where attachments (313) add lighting or beacons, include them in the approved product family (415) or keep them non-structural above the intercept plane.

312.5 Near-doors & glazing offsets

Heights must avoid door clashes and protect glass (234). Maintain setbacks so a crash rated bollard residual set (314) doesn’t hit glazing.

Frontages compress people and risk. Keep the head profile clear of door swing arcs and hardware, and ensure the residual set envelope at impact cannot contact mullions or the glazing edge offset. Where doors are glazed to ground, bias head height upward modestly so the intercept plane protects the lower lite.

Use Frontage/Door protection arrays (323) to coordinate setbacks with frontage protection (234) and maintain sightlines for staff and CCTV (237, 534).

312.6 Tolerance stack-up

Include fabrication, set-out, and surface tolerances (315, 612). Worst-case height still meets HVM bollard intent and crash rated bollard certificate limits.

Build a simple tolerance budget: tube cut length ±, sleeve/plinth level ±, grout bed ±, surface reinstatement ±. Sum worst-case in the unsafe direction (shorter effective height). If margin is tight, increase nominal head by the budget plus a small margin of safety, or switch to a head form that preserves intercept elevation (313).

Record the agreed budget in the drawings (931) and verify during Setting-Out & Benchmarks (612) and Datum & Alignment Checks (626). The SAT checklist (632–636) should include a Go/No-Go height gauge photo for each lane.

312.7 Visual proportioning

Align head heights with street furniture (238, 316). Good proportion improves public acceptance without weakening a crash rated bollard.

Even when security drives the number, proportion sells the outcome. Keep heads broadly level across vistas, align with adjacent benches/planters tops where practical, and avoid “saw-tooth” profiles on gentle grades by using micro-plinths. Where branding requires color bands (366), place them at a consistent eye-down elevation to aid conspicuity without mimicking traffic signs.

312.8 Maintenance access at height

Allow reach for cleaning/repairs (365). Safe access sustains HVM bollard availability and protects crash rated bollard fixtures.

Set head heights so routine tasks—cleaning lenses, tightening fixings, replacing beacons—are reachable without unsafe ladders. For automatic systems, check that raised heads do not complicate HPU access panels or enclosure clearances (347). In coastal or dusty sites (363), slightly higher heads can reduce splashback contamination of sensors (343).

312.9 Setting-out tips

Use leveled jigs and datum sticks; verify before pour (626, 333). Early checks lock HVM bollard heights and preserve crash rated bollard compliance (421).

Prepare a simple key plan with elevation call-outs at each bollard centerline. Use a leveled jig to hold sleeve tops, and a marked datum stick for quick cross-checks at curb, carriageway, and plaza locations. Photograph each position with the stick visible for the photo/redline logbook (937) before gate pours (620–624). Corrections after concrete are slow and costly.

312 Height setting for HVM/Crash-Rated Bollards — FAQ