HVM Planters Buyer's Guide

What is a HVM Planter

A certified HVM planter is a vehicle security barrier (VSB) housed within a planting container. The planting itself is genuine and requires the same horticultural maintenance as any other public realm scheme, but it plays no role in the product's security function. Resistance is provided by a structural element concealed within the planter (either a crash-rated bollard or an engineered concrete block) and it is this element that is independently tested and carries a documented performance rating.

The distinction is significant where a scheme must demonstrate certified protection, whether for a Vehicle Dynamics Assessment, a wider security strategy informed by NPSA guidance, or obligations arising under the Terrorism (Protection of Premises) Act 2025, commonly known as Martyn's Law. An untested planter, regardless of its apparent solidity, does not satisfy these requirements. Only a product with a documented test certificate and performance rating can be relied upon as hostile vehicle mitigation.

Rated Bollard Core Versus Rated Block Core

Two distinct engineering approaches are used to achieve certified resistance within a planter structure.

A bollard-core planter, such as our Toledo CT40, incorporates one or more crash-rated steel bollards within the planter shell, typically anchored into a foundation in the same manner as a standalone HVM bollard. The bollard carries the certified performance rating, while the planter functions as cladding and landscaping around a structural core that behaves, in engineering terms, as a conventional root-fixed or shallow-mount bollard. Because resistance derives from a foundation-anchored steel element rather than mass alone, bollard-core planters can achieve high performance ratings while maintaining a relatively slim footprint, which is advantageous where planting area or pedestrian clearance is constrained.

A block-core planter relies instead on a heavy, purpose-engineered concrete CT Block, either integrated into the planter structure or forming its base. This approach makes block-core planters well suited to sites with buried services, shallow substrate, or archaeology close to the surface, as many are designed for surface mounting or shallow-mount installation, avoiding the need for a full foundation.

Testing Standards: PAS 68, IWA 14 and ISO 22343

For close to two decades, PAS 68, first published by BSI in 2005, was the principal UK standard for this testing, with IWA 14-1 introduced in 2013 as its international equivalent under ISO's workshop agreement process. Both standards defined how a vehicle of specified mass is driven into a barrier at a set speed and angle, and how the resulting penetration and debris dispersal are measured and classified.

In September 2023, both PAS 68 and IWA 14-1 were formally superseded by ISO 22343-1, a single harmonised international standard. NPSA has, from March 2024 onward, recognised only ISO 22343-1 ratings for newly tested products, although products certified under the earlier standards prior to that date remain valid and continue to appear in NPSA's Catalogue of Security Equipment. Retesting of previously certified products is not required.

In practice, "PAS 68" remains the most referenced term in existing certificates, specifications and general industry usage, even though current testing is conducted under ISO 22343-1.

Vehicle Attack Delay Standard (VADS)

A crash rating establishes performance against a single, deliberate high-speed impact. It does not, by itself, indicate how a barrier performs under a sustained, lower-speed attack involving repeated ramming or nudging over an extended period. NPSA's Vehicle Attack Delay Standard, VADS, was developed to assess this scenario specifically.

Current NPSA guidance states that barriers holding only a crash rating under ISO 22343-1, IWA 14-1 or PAS 68 have not been proven effective against this form of attack and recommends that products intended for sites where this threat is credible hold both a crash rating and a VADS rating. This applies particularly to temporary event perimeters and pedestrianised schemes that rely on planters as part of the barrier line.

HVM Planter Installation: Foundations and Mounting Method

Installation method is a determining factor in product selection and should be established at an early stage of specification. Root-fixed installation, involving a full concrete foundation, is generally associated with the highest performance ratings but requires the greatest degree of excavation and is least accommodating of buried services.

Shallow-mount systems, such as those offered by Broxap Townscape, achieve comparable ratings with reduced foundation depth, suiting sites where standard depths would conflict with utilities or existing hardstanding. Ultra-shallow mount, such as our Gunwharf CT Ultra Shallow Mount Planter, extends this further for locations where even a shallow foundation is impractical, a common condition in historic town centres and transport interchanges where drainage, cabling or archaeology lie close to the surface.

Regardless of mounting type, a rated planter retains its performance rating only when installed exactly as tested, including foundation depth, ground preparation and fixing method. Any deviation from the tested installation invalidates the rating.

Perimeter Design and Protection

A single rated planter arrests one vehicle at one point of impact. A perimeter is protected by a coordinated arrangement of units, with spacing calculated to ensure no vehicle can pass between adjacent planters regardless of approach angle. Spacing that appears adequate on a landscape drawing may not withstand actual vehicle track widths, which is why a Vehicle Dynamics Assessment is typically used to establish realistic approach speeds and angles for the specific site, informing both the required performance rating and the layout of the scheme.

Planters are rarely deployed in isolation. Most schemes combine them with bollards, blockers or other VSB types to maintain continuous perimeter protection, reserving planters for locations where visual integration is most important, such as building entrances, seating areas and transport interchange frontages, while less sensitive sections may use bollards or blocks with a plainer appearance. Planting arrangement can also support pedestrian route definition, complementing rather than substituting for the certified barrier.

Selecting Between a Bollard-Core and Block-Core Planter

Selection typically depends on several site-specific factors. Ground conditions are usually the primary consideration: dense services, shallow substrate or heritage constraints tend to favour a block-core, surface-mounted or shallow-mount solution, whereas open ground with capacity for a full foundation allows greater flexibility to specify a bollard-core unit.

Footprint is a further factor, as bollard cores generally permit a slimmer planter with proportionally more usable planting area, while block cores require a larger base, which can be an aesthetic advantage in schemes where visible mass is a design objective rather than something to minimise.

Where the assessed threat involves a heavy vehicle, such as an N2 or N3 classification at higher speed, the foundation depth associated with bollard cores often makes it more practicable to achieve the required rating without an excessively large planter footprint.

Materials and Aesthetic Integration

Steel-clad planters offer the cleanest lines and the widest range of finishes, including powder coating to match existing street furniture.

Concrete planters, finished as-cast, rendered or with an aggregate surface, are well suited to larger civic spaces where visible mass forms part of the design intent.

Timber-clad planters, in which a rated core is enclosed within real or composite timber, are frequently specified in conservation areas and heritage town centres, where visibly industrial security infrastructure would be inconsistent with the surrounding streetscape. The timber cladding provides no structural function but materially affects how the installation is perceived.

Planting design should account for root systems that could compromise fixings over time, and for growth patterns that may obstruct sightlines if not properly managed at the design stage.

Maintenance and Inspection

A suitable maintenance regime for a HVM planter should include regular structural inspection of fixings, foundations and cladding for corrosion, movement or cracking; drainage checks, given that waterlogged planting beds adjacent to steel or concrete elements accelerate corrosion and increase stress on foundations under freeze-thaw conditions; a defined procedure for assessing any impact, however minor, including determination of whether the structural core requires replacement before the unit can be considered rated again; and retention of service records as part of site compliance documentation, which is of increasing relevance where a scheme forms part of a Martyn's Law risk assessment. Inspection frequency should be established according to the operational conditions of the specific site rather than a generic default interval.

Specification Requirements

Prior to specification, a buyer should confirm the complete performance rating code, including test standard, vehicle mass and class, speed, angle, penetration and debris dispersal figures, rather than relying on a general reference to PAS 68 testing. Confirmation of mounting type and required ground preparation should be obtained, along with clarification of whether the rating applies to the structural core alone or to the fully assembled planter as tested, since cladding or planting arrangements may occasionally differ from the tested configuration. Where the site presents a credible risk of sustained or repeated attack, a VADS rating should be sought alongside the crash rating. An aftercare and maintenance plan should form part of the specification process from the outset, ideally supported by technical advice on array spacing and installation constraints specific to the site.

Certification represents only one stage in a wider chain of assurance. Effective protection depends on an accurate threat and vehicle dynamics assessment, correct specification and ground investigation, installation carried out precisely as tested, and maintenance sustained for the operational life of the scheme.