Interpretation of the EN1317 Standard for Highway Guardrails

BS EN 1317-1:2010 was approved by CEN on 29 April 2010.

In order to improve and maintain highway safety, the design of safer roads requires, on certain sections of road and at particular locations, the installation of road restraint systems. These road guardrail systems are designated to redirect errant vehicles with a specified performance level and can provide guidance for pedestrians or other road users. 

This European Standard is a revision of EN 1317-1:1998. The standard identifies test methods and impact test acceptance criteria that the products for road restraint systems need to meet to demonstrate compliance with the requirements, given in EN 1317-5 and/or prEN 1317-6. The design specification, for road guardrail systems entered in the test report, identify important functional site conditions in respect of the test installation. 

1. Performance classes 

Safety barriers including vehicle parapets shall conform to the requirements of Containment levels, Impact severity and Deformation of the restraint system when tested in accordance with impact test criteria defined in Table as following. 

Test     Impact speed(km/h)    Impact angle°     Total mass(kg)    Type of vehicle 

TB11             100                            20                        900                        Car 

TB21              80                              8                        1300                       Car 

TB22              80                             15                       1300                       Car 

TB31              80                             20                       1500                       Car 

TB32             110                            20                       1500                       Car 

TB41              70                              8                        10000                 Rigid HGV 

TB42              70                             15                       10000                 Rigid HGV

TB51              70                             20                       13000                     Bus 

TB61              80                             20                       16000                 Rigid HGV 

TB71              65                             20                       30000                 Rigid HGV

TB81              65                             20                       38000             Articulated HGV 

2.Containment levels 

The containment levels of safety barriers including vehicle parapets shall conform to the requirements of Table follows when tested in accordance with the vehicle impact test criteria defined in Performance classes . 

NOTE 1 Low angle containment levels are intended to be used only for temporary safety barriers. Temporary safety barriers can also be tested for higher levels of containment. 

NOTE 2 A successfully tested barrier at a given containment level should be considered as having met the containment requirements of any lower level, except that N1 and N2 do not include T3, H-Levels do not include L-Levels and that H1, ..., H4b do not include N2. 

NOTE 3 Because testing and development for very high containment safety barriers in different countries has taken place using significantly different types of heavy vehicles, both tests TB 71 and TB 81 are included in the standard at present. The two containment levels H4a and H4b should not be regarded as equivalent and no 

hierarchy is given between them. The same holds for the two containment levels L4a and L4b. 

NOTE 4 The performance of Containment Classes L is enhanced in respect to the corresponding H classes by the addition of Test TB 32. 

The evaluation of a vehicle restraint system within the range of containment levels T3, N2, H1, H2, H3, H4a, H4b, L1, L2, L3, L4a and L4b shall require the carrying out of different tests: 

a) A test according to the maximum level of containment for that particular system;

b) Test(s) using cars in order to verify that satisfactory containment of the maximum level is also compatible with safety for a range of cars. 

3. Impact severity 

The evaluation of vehicle occupant impact severity assessment indices ASI and THIV shall be carried out for cars. For cars ASI and THIV shall conform to the requirements of Table. These indices are defined in EN 1317-1:2010. As a function of the value of the ASI and THIV indices, three impact severity classes A, B and C are defined in 

Table . Impact severity level A affords a greater level of safety for the occupant of an errant car than level B, and level B greater than level C. Test measures, appropriately adjusted in accordance with EN 1317-1:2010, 6.3, shall be directly compared to the values in Table . 

EN1317 standard reserves the highway guardrail Containment levels: H1W1,H1W2,H1W3,H1W4,H2W1,H2W2,H2W3,H2W4,H2W5,H3W3,H3W4,H4BW3,H4AW4,etc. 

In the following technical analysis, we will explain the design plans for each of these highway guardrail grades one by one.