Perimeter, Stand-Off, Vehicle and Entrance Security under GEBSS

A secure building does not begin at the front door.

Under the Guidelines for Enhancing Building Security in Singapore (GEBSS), security begins with how a potential threat can approach the site, how close it can get to the building, where vehicles and pedestrians cross the perimeter, and what prevents an intruder from progressing towards Critical Assets.

This is why GEBSS treats stand-off distance, perimeter protection, vehicle security barriers, access roads and entrances as connected parts of the same security problem.

The basic principle is:

The closer an uncontrolled threat can get to the building or Critical Asset, the more the building may have to depend on other protection measures.

At the same time, GEBSS does not prescribe maximum protection for every site. Protection should be selected according to the applicable risk, security requirement, financial feasibility and site constraints.

What is a perimeter line under GEBSS?

A perimeter line establishes a controlled area around a building or asset.

It may follow the property boundary, but its security purpose is more important than simply marking ownership.

GEBSS explains that physical barriers can:

restrict movement, channel people and vehicles, impede unauthorised access and form a continuous protective line around the site.

Perimeter measures can also provide deterrence and should contribute to detecting, delaying and/or denying access.

This makes the perimeter the first major physical layer between an external threat and the building.

Does every building need a perimeter fence?

No universal requirement like this should be taken from GEBSS.

GEBSS discusses several possible ways of establishing a perimeter, including:

fences, walls, bollards, planters and other physical barriers.

The appropriate solution depends on the threat, site and required protection level.

A dense city development may therefore have a very different perimeter strategy from a standalone critical facility.

The important question is not simply:

“Does the property have a fence?”

It is:

“Can an unauthorised person or vehicle approach the vulnerable parts of the building without being detected, delayed or controlled?”

What is stand-off distance?

Stand-off distance is the separation between a potential explosion location and the building being protected.

GEBSS describes sufficient stand-off as one of the most effective ways of reducing explosion effects because increasing distance can reduce the protection subsequently required for structural elements.

A perimeter can help create this distance by establishing where an uncontrolled vehicle or other threat can no longer proceed.

How much stand-off distance does GEBSS require?

There is no single ideal stand-off distance stated for all buildings.

GEBSS says the appropriate distance varies according to factors including:

the type of threat, construction method and desired protection level.

Its guidance is that stand-off should be maximised where possible.

Therefore, statements such as:

“GEBSS requires exactly 10 metres of stand-off”

would not accurately represent the guideline.

The appropriate value depends on the specific design and threat assessment.

Why is stand-off particularly important for vehicle threats?

Vehicles present a particular problem because they combine:

size, carrying capacity and speed.

GEBSS identifies several possible vehicle threats, including delivery of large explosive devices, ramming attacks against people or Critical Assets, and using a vehicle to breach the perimeter and introduce armed attackers.

The objective of a vehicle anti-ramming perimeter is therefore to stop unauthorised vehicles from approaching too close to the building.

What is a Vehicle Security Barrier?

A Vehicle Security Barrier (VSB) is a protective element intended to prevent hostile or unauthorised vehicles from crossing a security boundary.

GEBSS discusses both fixed and active VSBs.

Examples include:

bollards, hardened walls, raised features, planters and active barriers that can open and close for authorised traffic.

The barrier is not selected simply because it looks strong.

Its required performance should relate to the vehicle threat against which it is expected to protect.

Do security bollards need to be crash rated?

If the bollards are intended to reliably stop hostile vehicles, GEBSS says the VSB should be crash-rated through an appropriate certification test.

It specifically warns that not all VSBs available in the market are crash rated.

The certification indicates the level of protection provided and should be considered when selecting the barrier.

This creates an important distinction between:

architectural bollards

and

security bollards designed and certified to stop vehicles.

They may look similar but do not necessarily provide the same performance.

Does every bollard outside a building need to be crash rated?

No.

The requirement depends on what the bollard is expected to do.

A streetscape bollard intended only to guide pedestrians is not performing the same function as a barrier intended to stop a hostile vehicle.

Consultant’s perspective

The first question when specifying a bollard should therefore be:

“Is this primarily a streetscape element, or is it part of the vehicle anti-ram security perimeter?”

If it performs a security function, the required performance needs to be established accordingly.

How far apart should anti-ram bollards be?

GEBSS gives a specific design consideration for a vehicle anti-ramming perimeter line.

It says the edge-to-edge distance between discontinuous VSBs such as bollards, or the clear space between adjacent barriers, should be no more than 120 cm.

It also states that the minimum VSB height should be 65 cm above ground level.

These dimensions should not be casually interpreted as specifications for every decorative bollard installed in Singapore.

They are presented within GEBSS’s design guidance for the anti-ramming perimeter.

Why does approach speed matter when designing bollards?

A vehicle barrier has to deal with the impact created by an approaching vehicle.

GEBSS therefore says potential vehicle approach speed should be considered from the initial design stage.

It suggests using road geometry or traffic obstacles near entry points to reduce speed, which can in turn reduce the protection demand on the VSB.

This illustrates an important GEBSS principle:

Do not solve every security problem with a stronger product if the site design can reduce the threat first.

Can road design itself improve vehicle security?

Yes.

Vehicle approach geometry can form part of the protective strategy.

Instead of allowing a long, straight road directly towards a building or entrance, the site design can make it more difficult for a vehicle to achieve high speed.

GEBSS discusses measures such as bends and other traffic-control features in its vehicle-entrance guidance.

Consultant’s perspective

This means anti-ram security should be coordinated with:

architecture, civil design, landscape design and traffic engineering.

It is not simply a bollard supplier’s scope.

What is penetration distance?

Even when a vehicle hits a barrier, it may continue moving beyond the point of impact.

GEBSS says the distance the vehicle penetrates after striking the VSB should be considered when designing the perimeter because this affects the effective stand-off distance between the stopped vehicle and the building.

Therefore, putting a crash-rated barrier at a particular location does not automatically mean everything immediately behind the barrier is protected.

The barrier’s tested performance matters.

Can planters be used as security barriers?

Yes, GEBSS discusses hardened planters as one method of providing vehicle protection.

It also considers hardened:

walls, street furniture and other architectural elements.

The wider design objective is to combine the required protection with the architectural and public-realm environment.

This supports an important GEBSS philosophy:

Physical security does not always need to look like physical security.

A protective element can also contribute to landscaping or streetscape design, provided its required security performance is achieved.

Can benches or street furniture provide vehicle protection?

Potentially.

GEBSS discusses hardened street furniture such as:

benches, seating barriers, lamp posts, signposts and sculptural elements

that can be designed to perform a function similar to bollards.

Again, their effectiveness depends on their actual protective design rather than their appearance alone.

What is a pedestrian anti-intrusion barrier?

A pedestrian anti-intrusion barrier is intended to prevent unauthorised people from crossing the perimeter and approaching the building.

It may consist of:

a fence or wall, suitable foundation, top protection and potentially an intrusion-detection system.

The physical barrier performs primarily a delay function.

Even a strong perimeter is not assumed to be impossible to breach.

The purpose is to make intrusion sufficiently difficult that it can be detected and responded to.

How high should a security perimeter fence be?

Within its anti-intrusion barrier guidance, GEBSS identifies a minimum barrier height of 2,400 mm, referencing BS 1722-10.

It also recommends a minimum footing depth of 300 mm to delay tunnelling attempts.

Other considerations include consistent perimeter protection, avoiding climbing aids, limiting gaps under gates and coordinating detection and surveillance systems.

Again, this is specifically within the GEBSS anti-intrusion perimeter context rather than a statement that every ordinary property fence in Singapore must be 2.4 metres high.

Why should a fence work together with intrusion detection?

Because the physical fence is intended to delay the attacker.

An intrusion detection system can provide the Detect layer.

Together:

Fence creates delay → sensor identifies the attempt → alarm is raised → security responds.

Without detection, a determined intruder may have time to work on defeating the physical barrier without intervention.

This directly reflects the GEBSS Defence-in-Depth philosophy.

Can CCTV replace a perimeter fence?

Not necessarily.

CCTV primarily contributes to surveillance and detection.

A fence or barrier provides physical delay or denial.

They perform different functions.

In some situations, GEBSS notes that intrusion detection without a physical barrier may be considered where there is a sufficiently large buffer area for security forces to respond before the intruder reaches the building.

The underlying issue remains response time versus the time available to the attacker.

Why are building entrances considered security weak points?

A continuous protective line has to be opened whenever authorised people or vehicles enter.

GEBSS therefore describes vehicle and pedestrian access points as weak links in the perimeter because they create an opening every time they operate.

The challenge is to achieve two competing objectives:

prevent unauthorised access

while

allowing authorised people and vehicles to move efficiently.

This is why entrance design must consider both security and throughput.

Should a building minimise the number of entrances?

GEBSS says the number and positioning of entry points should be optimised, with entrances preferably located at less vulnerable positions.

This does not mean eliminating necessary operational or emergency exits.

Rather, unnecessary access points increase:

the number of openings to protect, the number of locations to monitor and the number of opportunities for unauthorised entry.

When should vehicle and pedestrian entrances be designed?

Early.

GEBSS says planning for vehicle and pedestrian access and entry control should begin during the initial stages of a new project.

This allows the design team to understand expected vehicle and pedestrian flow and balance security screening requirements against operational throughput.

Once roads, ramps and entrances have been constructed, correcting fundamental security-design problems can become difficult.

How should a secure vehicle entrance be positioned?

GEBSS recommends locating the vehicle entry-control point as far from the building as practicable.

It also says roads running beneath parts of the building should be avoided and access roads should encourage vehicles to approach at low speed.

The security point should give personnel sufficient visibility of approaching vehicles.

These design choices increase the opportunity to identify and manage a vehicle before it reaches the building.

What happens if a vehicle fails the security check?

The entrance should allow a rejected vehicle to leave without first entering the secure site.

GEBSS specifically says a route should be available for denied vehicles to exit without entering the premises or requiring queued vehicles to be moved.

Consultant’s perspective

This is a small design detail that can create a major operational problem if missed.

If the only way for a rejected vehicle to turn around is after the security barrier, the screening point has already failed to maintain the intended boundary.

Should delivery vehicles use a separate entrance?

GEBSS says a designated delivery and service vehicle entry point should be provided, preferably away from Critical Assets and areas where large numbers of people gather.

It also says the design should consider future vehicle-inspection technologies.

This is sensible because delivery vehicles may differ significantly from normal passenger vehicles in:

size, weight, duration on site and access requirements.

Should loading-dock vehicle barriers have the same protection as the main perimeter?

Where a dedicated delivery or service access-control point is provided, GEBSS says it should have video surveillance and an active VSB crash-rated to the same performance criteria as the anti-ramming perimeter line.

It also points out that vehicles accessing loading docks may be significantly heavier than vehicles using ordinary access points.

That is important when establishing the vehicle threat used to select the barrier.

Does vehicle screening replace pedestrian screening?

No.

GEBSS makes this point explicitly.

A person inspected while inside a vehicle does not normally receive the same level of scrutiny as someone passing through a pedestrian screening point.

Therefore, when a vehicle entrance leads into an underground or multi-storey car park, the subsequent entrance from the car park into the building should receive the same level of pedestrian screening as other pedestrian entrances.

This is an important building-security principle:

The car park should not become a bypass around the main pedestrian security layer.

What types of entrances does GEBSS consider?

For a typical building, GEBSS distinguishes vehicle access for:

authorised users, visitors and delivery vehicles.

For pedestrians, it identifies resident/visitor access and contractor/service access.

This does not necessarily mean five physically separate gates are required.

GEBSS notes that these functions may be provided at separate locations or incorporated together.

The purpose is to recognise that different users may require different entry processes.

Should pedestrian entrances also be positioned away from the building?

Where possible, yes.

The pedestrian security point can act as another layer between the external public environment and the protected facility.

GEBSS’s protected entrance guidance recommends considering entrance location so that an incident at the entrance does not easily affect the inner parts of the site.

That means entrance design is not only about identifying who may enter.

It is also about limiting the consequences if an attack occurs at the checkpoint itself.

What is a protected pedestrian entrance?

A protected pedestrian entrance combines controlled access with physical protection and potentially security screening.

GEBSS says the entrance portal should provide protection consistent with the building envelope and should resist bypass by:

breaking through, climbing over or passing underneath.

It also discusses separate waiting areas before and after security screening and different operational requirements during and after office hours.

What is an interlocking entrance?

An interlocking entrance uses multiple controlled barriers so that movement through the entrance can be managed in stages.

Where an interlocking arrangement is required, GEBSS discusses applying it at both entrances and exits and using the area between barriers as a potential screening area.

Consultant’s perspective

The security benefit is that the building does not have to expose the complete inner security boundary whenever the outer gate opens.

However, the arrangement must also consider:

flow, emergency evacuation, accessibility, reliability and operational requirements.

Should screening take place before or after the final security gate?

GEBSS says where security screening is undertaken, or may be required in future, it should occur before the final gate line.

For an interlocking system, the space between the barriers may be used for screening and should preferably be outside the perimeter line.

The document also recommends avoiding screening areas beneath populated or vulnerable portions of the building where practicable.

Should buildings allow space for screening even if they do not currently screen people?

This is one of GEBSS’s useful future-planning concepts.

Even where normal threat levels do not justify intensive screening, the building can be designed to accommodate enhanced controls later.

GEBSS says screening-equipment requirements should consider matters such as:

space, floor loading, electricity, guard positions and lighting.

The intention is to avoid discovering during a heightened security situation that the building physically cannot accommodate the required screening operation.

How should turnstile capacity be selected?

GEBSS says the pass-through rate of automated gates and turnstiles should be consistent with:

the desired processing speed and expected pedestrian flow.

This is important because an access-control point that cannot handle normal peak flow can create:

queues, crowd concentration and pressure to bypass security procedures.

Security and operational performance therefore need to be designed together.

What happens to an active barrier during a power failure?

GEBSS says the failure mode of an active VSB should be deliberately evaluated so it fails in a predetermined position, open or closed, according to security and operational requirements.

It also discusses backup generation or manual override to maintain operation during power or equipment failure.

The same broader issue appears in protected pedestrian gate design.

There is not one universal rule that every barrier must automatically fail open or fail closed.

The intended behaviour depends on the application.

Are active bollards dangerous?

They can be.

GEBSS specifically warns that active VSBs can cause serious injury even when operating normally.

It therefore discusses measures to increase their visibility and safety, including:

warning markings, reflectors, lighting, warning signals and vehicle-detection safety systems.

Security performance should not be achieved without considering operational safety.

Can a normal drop-arm car park barrier stop a hostile vehicle?

Not necessarily.

GEBSS distinguishes normal traffic barriers from barriers designed and tested for anti-ram protection.

A conventional drop-arm barrier may manage vehicle access but does not automatically possess the structural performance required to stop a hostile vehicle.

The same principle applies to gates and bollards:

Access control equipment and anti-ram equipment are not automatically the same thing.

Does a crash-rated barrier solve the entire vehicle-security problem?

No.

A secure vehicle entrance involves more than the barrier itself.

The design may also need to consider:

vehicle approach speed, barrier location, penetration distance, stand-off, screening, pedestrian movement, rejected-vehicle routes, visibility, power failure and response.

This is why GEBSS approaches the subject as site design, not merely product selection.

A practical way to review perimeter and entrance security

A useful design review can follow the path of the threat:

This is a consultant’s review framework based on the GEBSS design concepts.

Common misunderstandings about GEBSS perimeter security

“A line of bollards means the building has anti-ram protection.”
Not necessarily. GEBSS distinguishes crash-rated VSBs from products that may not have demonstrated vehicle-stopping performance.

“There is a standard GEBSS stand-off distance for every building.”
No. GEBSS expressly says there is no ideal distance applicable to every case.

“The strongest bollard is always the best solution.”
Not necessarily. GEBSS also considers approach speed, penetration, site conditions and architectural integration.

“Vehicle screening means passengers are already security screened.”
No. GEBSS specifically says vehicle-entry passenger screening generally does not replace pedestrian screening.

“The gate is just an opening in the fence.”
GEBSS treats entrance points as weak links because they interrupt the protective perimeter.

“We can decide on bollards and screening equipment after construction.”
GEBSS repeatedly stresses early planning because vehicle barriers, road geometry, foundations, screening space and entry configuration may be difficult to retrofit effectively.

Conclusion

GEBSS treats perimeter security as much more than fences and gates.

The perimeter establishes how close an uncontrolled threat can get to the building.

Stand-off creates distance.

Vehicle Security Barriers prevent hostile vehicles from penetrating that distance.

Pedestrian barriers delay unauthorised entry.

Vehicle and pedestrian entrances control the intentional gaps in the protective line.

Screening, surveillance and access control help determine who or what should be allowed through.

The design therefore needs to work as one connected system:

Approach → Perimeter → Stand-Off → Entrance → Screening → Access Control → Building

The key principle is:

Do not start perimeter security by choosing a bollard or gate. Start by understanding how the threat can approach the site, where it should be stopped, and what happens at every point where the protective boundary has to open.