Shallow-mount security bollard installation

What is it?

What are shallow-mount security bollards?

A shallow-mount bollard is a crash-tested security bollard designed to sit in a much shallower foundation than a conventional rated post, often by spreading impact loads along a linked steel frame or beam. It is used where cables, pipes, basements or structural slabs leave too little depth for a deep foundation. Like any rated product, its performance applies only to the configuration and foundation that were tested.

City-centre footways rarely have a metre or more of clear ground. Fibre ducts, gas mains, water pipes and old cellars sit just below the paving, and moving them can take longer and cost more than the security work itself. Shallow-mount systems were developed for exactly these sites, letting a protective line be installed above services that must stay where they are.

We install manufacturer-tested shallow-mount systems to the exact foundation drawing, using installation crews working under our management. The choice of system, its rating and the layout come from the client's security adviser or the manufacturer; we check the ground can accept the tested design before committing to it, and we record the build so the rating can be demonstrated.

Where shallow-mount bollards make sense

• Footways with dense utility runs just below the surface
• Podium decks, car park roofs and basement slabs
• Bridges and structures where excavation depth is limited
• Listed or historic streets where deep digging is unwelcome
• Retrofits outside occupied buildings with tight programmes
• Sites where service diversions would be slow or impractical
• Lines that must cross over shallow drainage or ducts

How it works

A deep rated bollard resists impact by leverage against a large block of concrete in the ground. A shallow system works differently: the posts are joined below the surface by a steel frame, beam or base cassette, so the force from a vehicle hitting one post is shared across several neighbouring posts and a wide area of foundation. Excavation depths are commonly a few hundred millimetres rather than more than a metre, which is often enough to pass over services instead of through them.

Because the posts work as a group, the tested unit is usually a run of bollards rather than a single post. Manufacturers state the minimum number of posts, the maximum gap and how the ends of a run must be detailed. Some systems are modular, with frame sections bolted together on site so that a line can step around obstacles such as tree pits or inspection chambers within limits set by the manufacturer.

On a suspended slab or deck there is a further question: whether the structure can take the loads the system transfers into it during an impact. That is a matter for a structural engineer, and the answer may lead to a different product or a different foundation approach.

Options and finishes

Typical specification

How we install it

Ground, foundations and buried services

Shallow does not mean simple. The trench has to sit over services with enough cover to protect them, but the frame also needs a firm, consistent bearing; soft spots, old backfill around pipe trenches and voids under paving can all need treating first. Utility owners may set minimum separation distances or ask to be present when digging near their apparatus. On decks and roofs, the waterproofing and drainage layers must be protected or rebuilt, and fixings must not puncture membranes unless the structural and waterproofing designers have agreed a detail. Paving is often natural stone in the streets where these systems are used, so careful lifting, storage and relaying is part of the job.

Rules and checks before you order

• Keep the test certificate for the exact system and configuration, including the minimum run length and end details.
• Get written confirmation from a structural engineer before installing on slabs, decks, basements or over voids.
• Agree works and separation distances with utility owners, and with the highway authority where the line is on public highway.
• Check gaps work for wheelchair users and buggies while still stopping vehicles, referring to Inclusive Mobility guidance.
• Record the frame's position on as-built drawings so future excavation near the line can be planned safely.

See rules and standards by nation for highway consent, accessibility and security standards.

Maintenance

Once cured, a shallow-mount line needs much the same care as any static rated barrier: periodic visual checks, cleaning of covers and renewal of visibility bands. Pay attention to the surface around the posts, because settlement or loose paving can indicate movement in the bearing layer. If one post is struck, the frame may have transmitted load to its neighbours, so the whole run near the impact should be checked with the manufacturer rather than replacing a single post in isolation. Any later utility work beside the line should be supervised so the frame is not undermined.

What affects the price

• Length of run and the system needed to achieve the rating
• Amount of hand digging needed around live services
• Structural engineering checks on slabs or decks
• Lifting, storing and relaying natural stone paving
• Changes of direction, end details and removable positions
• Restricted working hours in busy streets or occupied sites