Frequently asked questions

Each barrier system tested to EN 1317 is awarded a working width class. This is calculated by adding the width of the system plus the amount of deflection that occurs when the system is impacted to the test criteria. The system’s deflection is measured from the traffic face of the system.

So, for example: For a system with a working width of W1, the total system dynamic deflection combined with the barrier width will not exceed 600mm, whereas a system with a performance level of W3 will not exceed 1000mm.

The system is measured from the traffic face of the VRS before impact, to the rear-most point of the VRS after impact i.e. how far the hazard needs to be away from the traffic face and not be impacted.

Containment levels are determined through impact tests where a vehicle of a specified mass and speed is driven into a barrier. The barrier’s performance is assessed based on factors like:

• Vehicle penetration: Whether the vehicle breaks through the barrier.
• Vehicle trajectory: The path the vehicle takes after impact.
• Occupant risk: The level of risk to the vehicle occupants.

Impact tests are carried out in accordance with EN1317-2 and determine key performance indicators such as containment level, working with, vehicle intrusion and impact severity levels.

Several factors influence the choice of containment level, including:

• Speed limit: Higher speed roads require higher containment levels.
• Traffic volume: Roads with heavy traffic may need a higher containment level.
• Roadside environment: The presence of hazards like steep slopes, water bodies, or structures will influence the required level.
• Vehicle type: Heavier vehicles require barriers with higher containment levels.

Containment level effectively refers to the size of vehicle that needs to be restrained

• N1: This is the lowest containment level, suitable for low-speed roads and situations where the risk of a vehicle leaving the road is minimal. It’s typically used for passenger cars and light commercial vehicles.

• N2: This level offers a higher level of containment than N1. It’s suitable for higher speed roads where there is a risk of more severe consequences if a vehicle leaves the road. N2 is also designed for passenger cars and light commercial vehicles but at higher speeds than N1.

• H1: This level is designed to contain heavier vehicles, such as buses and trucks. It is typically used on motorways and high-speed dual carriageways.

• H2: This level offers a higher level of containment than H1, suitable for heavier vehicles at higher speeds. It’s used in locations where the consequences of a vehicle leaving the road are very serious, such as bridges and locations with steep embankments.
  

This is a list of some containment levels, not all.

Containment levels refer to the ability of a road safety barrier to prevent a vehicle from breaking through or crossing over it in a collision. These levels are defined in European standards such as EN 1317, which classifies barriers based on their performance in impact tests.

Several factors should be considered when deciding on the placement and type of passive posts, including:

• Permitted speed: The speed limit of the road will influence the required energy absorption class of the post.
• Presence of other obstacles: Consider the risk of the vehicle hitting other objects after colliding with the post.
• Presence of pedestrians: Choose a post that minimises the risk to pedestrians and other road users.
• Energy absorption rating: Select the appropriate energy absorption class (HE, LE, or NE) based on the specific location and risks.
• Sign size: Larger signs increase the wind load on the post, potentially requiring a larger section post or additional supports to ensure stability.
• Wind speed: The prevailing wind speeds in the area should be considered. Higher wind speeds necessitate stronger and more robust posts to withstand the increased forces.

The Safe System Approach is a road safety strategy that aims to eliminate deaths and serious injuries on the roads. It acknowledges that human error is inevitable and focuses on creating a more forgiving road environment through a combination of engineering, education, and enforcement.

Passive posts are often used in locations where traditional safety barriers are unsuitable or pose a hazard, such as:

• Roundabouts and splitter islands: Where barriers could create a greater hazard.
• Areas with limited space: Where there isn’t enough room for a barrier run-off.
• Rural roads: Where a clear “run-off” area is available beside the road.

When a road crash occurs, the vehicle and its passengers quickly decelerate, and force is exerted on the vehicle. Modern cars have safety features that absorb kinetic energy in collisions, such as seat belts, air bags and crumple zones, but this is not always enough to prevent death or serious injury to the vehicle occupants.

Colliding with a heavier stationary object such as a traditional lamp post or signpost, which is not crash-protected, could have disastrous consequences for the vehicle and its passengers. If the force on impact is not sufficient to move the object, it will send a considerable force back to the vehicle. Whereas a light object, which moves easily on impact, will absorb some of the vehicle’s kinetic energy, thereby limiting the severity of the crash.

Passive posts enhance road safety by minimising the impact forces on a vehicle during a collision. Unlike rigid posts, they break away or deform, absorbing some of the kinetic energy and reducing the risk of serious injury to vehicle occupants.

BS EN 12767:2019 is the European standard that sets the performance requirements for passive safety of support structures for road equipment, such as signposts and lighting columns. It outlines how these structures should be designed and tested to ensure they reduce the risk of injury in the event of a collision.

Passive signposts, also known as passive sign supports, are designed to break away or deform upon impact with a vehicle. This reduces the severity of injuries to vehicle occupants in a collision. They are often used in places where traditional safety barriers might be impractical or pose a hazard themselves or where existing sign posts cannot be moved and has to be placed within the working width of the VRS.

The Health and Safety at Work Act 1974 places a duty on employers to ensure the health and safety of their employees and the public. HVM solutions play a crucial role in fulfilling this duty by mitigating the risk of vehicle-based accidents and attacks. By implementing appropriate HVM measures, organisations can help to create a safer environment for everyone.

The CPNI is the UK government authority that provides protective security advice and support to organisations responsible for national infrastructure. This includes essential services like energy, transport, water, and communications. CPNI helps these organisations assess risks, implement security measures, and protect against threats, including terrorism.

PAS 68 is a publicly available specification that sets the standard for impact testing of security barriers, bollards, and road blockers. It provides a rating system that indicates the ability of a product to withstand impact from a vehicle of a specified mass and speed. This helps specifiers and buyers choose the right HVM solutions for their needs.

The National Barrier Asset (NBA) is a collection of temporary security barriers and protective fencing deployed in the UK to protect against vehicle-based attacks. Managed by the National Vehicle Threat Mitigation Unit (NVTMU), the NBA is used at major events and crowded places to enhance public safety.

Please see relevant system manual for the minimum recommended values for length in approach of and depart of the hazard.

The length of our guardrail systems are based on a full-height length of need NOT including the need for terminals at either end. This ruling ensures the system would fall in line with the minimum length of full containment referenced within CD377, rounded up to to suit the nominal length of beam. This guidance is applicable for motorway and all-purpose trunk roads with speed limits of 50 mph or more.

For scenarios where a shorter length may be required or there are other limitations, please contact a member of our Technical team at technical@hill-smith.co.uk and we will be able to advise accordingly.

The document CD 377 – Requirements for Road Restraint Systems, applicable to the UK road network, stipulates that Vehicle Restraint System (VRS) products must comply with EN 1317 testing standards.

Other countries, such as the United States and Australia, utilise different testing standards, including MASH and NCHRP.

Please consult your country’s specific requirements to determine the applicable test standard for VRS to ensure compliant implementation on the road network.

A crash cushion is an energy absorption device installed in front of one or more hazards to reduce the severity of an impact. Typically they are used for temporary applications as opposed to permanent and can be used freestanding. 

Vehicle access control is about managing vehicle movement to enhance security, using physical barriers like gates and bollards, alongside rising bollards This helps protect public spaces, critical infrastructure, and private property. Access control is also used in construction sites and for highway maintenance teams.

A guardrail is a type of Vehicle Restraint System (VRS) used alongside or on the central reserve of a road to prevent vehicles from leaving the roadway or entering hazardous areas. They are also used to protect drivers and passengers from collisions with obstacles or embankments. Guardrails are a post and rail system, typically made of metal components. 

A road restraint risk assessment procedure, or RRRAP for short, is a formal examination of a road or highway project, carried out by an independent team of experts. The audit aims to identify potential safety issues and recommend improvements to enhance safety for all road users, including drivers, cyclists, and pedestrians.

The level of security required for an event depends on various factors, including the size and nature of the event, the anticipated crowd, the location, and the current threat level. A thorough risk assessment should be conducted to determine the appropriate security measures, which may include crowd control barriers and Hostile Vehicle Mitigation strategies.

A parapet is a restrain system installed along the edge of a bridge or elevated structure where there is a vertical drop. It acts as a safety barrier to prevent vehicles from leaving the roadway and falling off the bridge. Parapets also help to protect bridge users from the wind and serve as a visual guide for drivers.

Introduced to Parliament September 2024, Martyn’s Law is a proposed piece of legislation in the UK that would require public venues and spaces to implement security measures against terrorism. It’s named in memory of Martyn Hett, who was sadly killed in the Manchester Arena bombing in 2017. The law aims to enhance public safety and protect against future attacks.

Although not yet officially written into law, it’s expected to be passed and come into effect sometime in the future. Many organisations are already proactively implementing security measures.

Ideally, a VRS and HVM assessment should be conducted early in the planning stages of any new development or event. This allows for HVM/VRS measures to be integrated into the design, ensuring maximum effectiveness and minimising costly retrofits.  It’s also crucial to review measures periodically or when changes occur.

We can provide guidance for HVM & VRS design to ensure appropriate utilisation and optimisation of products. 

HVM stands for Hostile Vehicle Mitigation. It encompasses measures taken to reduce the risk posed by vehicles used in attacks. This includes temporary or permanent physical security measures like barriers and bollards, which we specialise in. HVM is predominantly utilised to protect pedestrians at large events as well as busy areas (town centres) and critical infrastructure, like government buildings.

VRS stands for Vehicle Restraint System. These systems, such as guardrails or parapets, are crucial in preventing errant vehicles from entering restricted areas or causing harm to pedestrians and infrastructure.  They are often used to improve road safety and protect vulnerable areas, such as roadside construction and maintenance.