Standard UNE-EN-1317

Vehicle containment systems (VCS) are those elements that provide a certain level of containment to an out-of-control vehicle and reduce the severity of the accident by absorbing part of its kinetic energy and redirecting its path.

The main characteristic defining the performance of any VCS is its ability to prevent a vehicle that leaves the road from reaching an obstacle, a different level or risk element that it is intended to protect against.

Since 1 January 2011, all vehicle containment systems installed on roads in the European Union must be certified under a new harmonised Standard, UNE EN 1317. This text has greatly contributed to the road safety sector as it homogenises the testing methodology and acceptance criteria of VCS across the whole continent.

The ultimate aim of the Standard is to guarantee that any VCS installed:

Ensures that the system contains the vehicle (without penetrating the system or overturning) – Containment level
Slow downs deceleration to minimise injury to its occupants – Impact Severity
Ensures that the vehicle will not fall down a slope, nor the vehicle or system impact any obstacle – System deformation
Guarantees that the vehicle will not cross into other lanes – Redirection

The performance of a containment system against vehicle impact essentially depends on the geometric and mechanical characteristics of the system’s individual constituent elements and assembly, as well as the type of foundations used. These variables result in different containment systems, which are distinguished by the effects and consequences that a vehicle impact has on the vehicle, its occupants and the system itself

According to the result obtained in full-scale crash tests, the Standard allows the performance of the VCS to be classified through a series of technical parameters:

CONTAINMENT LEVEL

Indicates the ability of a VCS to withstand the load from a vehicle’s impact.

Selecting the containment level that a safety barrier to be installed on the end of a road must have will depend on the risk of accidents, in turn defined by the speed of the road and the average intensity of HGVs in each direction at the time of implementation. In line with the previous definition, UNE EN 1317 defines several containment levels. Each containment level is acquired from successfully passing one or more full-scale tests. The list of tests accrediting each level is shown in the following table:

(*) The TB11 test aims to verify that the containment level of heavy vehicles is compatible with the safety of occupants in light vehicles.

UNE EN 1317 also defines the full-scale test conditions carried out in accredited laboratories, setting values for vehicle mass, speed at time of impact and the angle of impact against the barrier.

Once the containment level has been established, a complex system of laboratory-calibrated high-performance sensors and cameras allows the barrier’s performance in the tests to be defined using specific values of the following parameters.

IMPACT SEVERITY LEVEL

A vehicle impacting against a VCS carries obvious risks for its occupants. The severity of these risks inside the passenger compartment is determined by the impact severity level. This is calculated from the combination of deceleration (ASI) and head impact (THIV) values. Installing a VCS with an impact severity level of C is not permitted in Europe as this value presupposes an impact with a fatal outcome for the driver.

DEFORMATION OF THE SYSTEM

The performance of a VCS is characterised by the transverse displacement of the device during an impact. This is defined in the tests by means of dynamic deflection (D) and working width (W).

Dynamic Deflection (D):

The maximum lateral dynamic displacement on the side of the VCS facing the traffic. It is measured in metres.

Working Width (W):

The distance between the side of the containment system closest to the flow of traffic before the impact and the furthest lateral position that reaches any essential part of the VCS during the crash. The Standard classifies this parameter from W1 to W8 depending on the metres of displacement.

Vehicle Intrusion (VI):

This is the maximum dynamic lateral displacement of the side of the barrier facing traffic without deforming. It is evaluated using photographs or high-speed video and considers a hypothetical load with width and length equal to that of the floor of the vehicle, and a total height of 4m. The Standard classifies this parameter from VI1 to VI5 depending on the metres of displacement.

The following image shows several possible lateral displacement situations, and how the three parameters are measured in each case. The value does not relate to the type of VCS but the difference between the initial and final position of each VCS element and/or the vehicle.