Road restraint systems - Part 1: Terminology and general criteria for test methods
This European Standard contains provisions for the measurement of performance of products for the road restraint systems, under impact and impact severity levels, and includes:
- Test site data;
- Definitions for road restraint systems;
- Vehicle specification (including loading requirements) for vehicles used in the impact tests;
- Instrumentation for the vehicles;
- Calculation procedures and methods of recording crash impact data including impact severity levels;
The modifications included in this standard are not a change of test criteria, in the sense of EN 1317-5:2007, ZA.3.
Rückhaltesysteme an Straßen - Teil 1: Terminologie und allgemeine Kriterien für Prüfverfahren
Dieser Teil der Europäischen Norm enthält Vorschriften für die Messung der Leistung bei Anprall und der Stufen der Anprallheftigkeit von Rückhaltesystemen an Straßen und beinhaltet:
- Daten vom Prüfort;
- Definitionen von Rückhaltesystemen an Straßen;
- Fahrzeugfestlegungen für (einschließlich der Belastungsanforderungen an) Fahrzeuge, die für Anprallprüfungen eingesetzt werden;
- die Instrumentierung der Fahrzeuge;
- Berechnungsverfahren und Verfahren zur Aufzeichnung von Anpralldaten, einschließlich der Stufen der Anprallheftigkeit;
Die Abänderungen in diesem Teil der Europäischen Norm stellen keine Änderung der Prüfkriterien im Sinne von EN 1317 5:2007+A1:2008, ZA.3, dar.
Dispositifs de retenue routiers - Partie 1 : Terminologie et dispositions générales pour les méthodes d'essai
La présente Norme européenne contient des dispositions pour le mesurage de la performance sous choc des produits de type dispositifs de retenue routiers et les niveaux de sévérité de choc. Elle comprend :
- les données relatives au site d’essai ;
- les définitions des dispositifs de retenue routiers ;
- la spécification du véhicule (y compris les exigences de chargement) pour les véhicules utilisés lors des essais de choc ;
- l’instrumentation des véhicules ;
- les procédures de calcul et les méthodes d’enregistrement des données d’essai de choc, y compris les niveaux de sévérité de choc ;
- le VCDI.
Les modifications incluses dans la présente norme ne constituent pas un changement de critères d’essai au sens de l’EN 1317-5:2007+A1:2008, ZA.3.
Oprema cest - 1. del: Terminologija in splošna merila za preskusne metode
Ta evropski standard vsebuje določbe za merjenje delovanja proizvodov za opremo cest pred naletom in stopnje moči naleta ter vključuje:
- podatke o preskusnem mestu;
- opredelitve opreme cest;
- specifikacijo vozil (vključno z zahtevami za obremenitve) za vozila, ki se uporabljajo pri udarnih preskusih;
- merilno opremo za vozila;
- računske postopke in metode beleženja podatkov o obremenitvah pri trčenju, vključno s stopnjami intenzivnosti obremenitev;
Spremembe, vključene v ta standard, ne spreminjajo preskusnih meril v smislu EN 1317-5:2007+A1:2008, ZA.3.
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Oprema cest - 1. del: Terminologija in splošna merila za preskusne metodeRückhaltesysteme an Straßen - Teil 1: Terminologie und allgemeine Kriterien für PrüfverfahrenDispositifs de retenue routiers - Partie 1 : Terminologie et dispositions générales pour les méthodes d'essaiRoad restraint systems - Part 1: Terminology and general criteria for test methods93.080.30Cestna oprema in pomožne napraveRoad equipment and installations01.040.93Nizke gradnje (Slovarji)Civil engineering (Vocabularies)ICS:Ta slovenski standard je istoveten z:EN 1317-1:2010SIST EN 1317-1:2010en,fr,de01-november-2010SIST EN 1317-1:2010SLOVENSKI
STANDARDSIST EN 1317-1:19991DGRPHãþD
SIST EN 1317-1:2010
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
July 2010 ICS 01.040.93; 93.080.30 Supersedes EN 1317-1:1998English Version
Road restraint systems - Part 1: Terminology and general criteria for test methods
Dispositifs de retenue routiers - Partie 1 : Terminologie et dispositions générales pour les méthodes d'essai
Rückhaltesysteme an Straßen - Teil 1: Terminologie und allgemeine Kriterien für Prüfverfahren This European Standard was approved by CEN on 29 April 2010.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Avenue Marnix 17,
B-1000 Brussels © 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1317-1:2010: ESIST EN 1317-1:2010
EN 1317-1:2010 (E) 2 Contents Page Foreword . 3Introduction . 51Scope . 62Normative references . 63Abbreviations . 64Terms and definitions . 75Test methods . 105.1Test site . 105.2Test vehicles . 115.2.1General . 115.2.2Loading conditions . 116Vehicle Instrumentation . 136.1Vehicle Instrumentation required for the calculation of ASI and THIV . 136.2Frequency requirements . 136.3Compensation for instrumentation displaced from the vehicle centre of mass . 137Data Processing and Analysis . 158Test Results and Calculations . 178.1Severity Indices. 178.1.1General . 178.1.2Summary of the procedure to compute ASI . 178.1.3Procedure to compute THIV . 188.2Vehicle cockpit deformation index (VCDI) . 248.2.1Deformation . 248.2.2Location of the deformation . 248.2.3Extent of the deformation . 258.2.4Examples (informative) . 27Annex A (informative)
Calculation of the acceleration severity index (ASI) . 28Annex B (informative)
Vehicle acceleration - Measurement and calculation methods . 29B.1Introduction . 29B.2Acceleration in a rigid body . 29B.3Methods of measuring rigid body motion . 30B.4Measurement by six linear and three angular transducers . 31B.5Remarks . 35Bibliography . 36 SIST EN 1317-1:2010
EN 1317-1:2010 (E) 3 Foreword This document (EN 1317-1:2010) has been prepared by Technical Committee CEN/TC 226 “Road equipment”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by January 2011, and conflicting national standards shall be withdrawn at the latest by January 2011. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 1317-1:1998. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive(s). EN 1317 consists of the following parts: EN 1317-1, Road restraint systems Part 1: Terminology and general criteria for test methods; EN 1317-2, Road restraint systems Part 2: Performance classes, impact test acceptance criteria and test methods for safety barriers including vehicle parapets; EN 1317-3, Road restraint systems Part 3: Performance classes, impact test acceptance criteria and test methods for crash cushions; ENV 1317-4, Road restraint systems
Part 4: Performance classes, impact test acceptance criteria and test methods for terminals and transitions of safety barriers; prEN 1317-4, Road restraint systems Part 4: Performance classes, impact test acceptance criteria and test methods for transitions of safety barriers (under preparation: this document will supersede
ENV 1317-4:2001 for the clauses concerning transitions); EN 1317-5, Road restraint systems Part 5: Product requirements and evaluation of conformity for vehicle restraint systems; prEN 1317-6, Road restraint systems Pedestrian restraint systems
Part 6: Pedestrian Parapet (under preparation); prEN 1317-7, Road restraint systems Part 7: Performance classes, impact test acceptance criteria and test methods for terminals of safety barriers (under preparation: this document will supersede
ENV 1317-4:2001 for the clauses concerning terminals); prEN 1317-8, Road restraint systems Part 8: Motorcycle road restraint systems which reduce the impact severity of motorcyclist collisions with safety barriers (under preparation). Annexes A and B are informative. The significant technical changes incorporated in this revision are: 5
Test methods SIST EN 1317-1:2010
EN 1317-1:2010 (E) 4 The specifications for the test site and test vehicles have been moved from Parts 2 and 3 to Part 1. 6.1 Vehicle instrumentation required for the calculation of ASI and THIV The requirement of the 1998 text: Vehicle acceleration shall be measured at a single point (P) within the vehicle body close to the vehicle centre of gravity.
is replaced by: The accelerometers shall be mounted at a single point (P) on the tunnel close to the vertical projection of vehicle centre of mass of the undeformed vehicle, but no further than 70 mm longitudinally and 40 mm laterally. Measurements made before the publication of the present standard, with accelerometers fixed to an installation close to the centre of mass are accepted. 6.2 Frequency requirements The following new requirement has been introduced: Since the data will be filtered by recursive (Butterworth) filters, more data should be collected than is specifically required by the analysis. A recursive filter always produces "starting transients" at the beginning and end of the data, and requires time to "settle down". An additional 500 ms of data shall be collected at the beginning and end of the data; this extra data can then be discarded after filtering. 6.3 Compensation for instrumentation displaced from the vehicle centre of mass The procedure has been extended also to the cases of non-null roll angle and roll velocity and when the three points Q1, Q2, P (P1, P2, P in the 1998 text) are aligned along any straight line. 8.1 Severity Indices The requirement for the index PHD (Post impact Head Deceleration) has been removed. ASI and THIV are required. 8.1.1 Summary of the procedure to compute ASI In the procedure to compute ASI, averaging of the three components of the acceleration over a moving window of 50 ms has been replaced by filtering with a four-pole phaseless Butterworth digital filter.
8.2 Vehicle cockpit deformation index (VCDI) 8.2.2 Location of the deformation The prefix ‘ND’ has been added for impacts where there is no deformation of the vehicle cockpit. 8.2.3 Extent of the deformation "The sub-index 3 has been added for reductions greater than 20 %, or measurements which cannot be taken due to the deformation of the vehicle." According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. SIST EN 1317-1:2010
EN 1317-1:2010 (E) 5 Introduction 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 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 restraint systems entered in the test report, identify important functional site conditions in respect of the test installation. The performance range of the products for road restraint systems, designated in this standard, enables national and local authorities to recognize and specify the performance class to be deployed. Annexes A and B give informative explanation of the measurement of the severity index ASI and vehicle acceleration. SIST EN 1317-1:2010
EN 1317-1:2010 (E) 6 1 Scope This European Standard contains provisions for the measurement of performance of products for the road restraint systems, under impact and impact severity levels, and includes: Test site data; Definitions for road restraint systems; Vehicle specification (including loading requirements) for vehicles used in the impact tests; Instrumentation for the vehicles; Calculation procedures and methods of recording crash impact data including impact severity levels;
VCDI. The modifications included in this standard are not a change of test criteria, in the sense of
EN 1317-5:2007+A1:2008, ZA.3. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 1317-2, Road restraint systems
Part 2: Performance classes, impact test acceptance criteria and test methods for safety barriers including vehicle parapets EN 1317-3, Road restraint systems
Part 3: Performance classes, impact test acceptance criteria and test methods for crash cushions ENV 1317-4, Road restraint systems
Part 4: Performance classes, impact test acceptance criteria and test methods for terminals and transitions of safety barriers ISO 6487, Road vehicles
Measurement techniques in impact tests
Instrumentation ISO 10392, Road vehicles with two axles
Determination of centre of gravity 3 Abbreviations ASI: Acceleration Severity Index
ATD: Anthropomorphic Test Device
CAC: Channel Amplitude Class
CFC: Channel Frequency Class
Centre of mass
HGV: Heavy Goods Vehicle
PRS: Pedestrian Restraint System SIST EN 1317-1:2010
EN 1317-1:2010 (E) 7
RRS: Road Restraint System
THIV: Theoretical Head Impact Velocity
VCDI: Vehicle Cockpit Deformation Index
VRS: Vehicle Restraint System
4 Terms and definitions The types of system are shown in Figure 1.
Figure 1 — Types of system For the purposes of this document, the following terms and definitions apply. 4.1 road restraint system vehicle restraint system and pedestrian restraint system used on the road 4.2 vehicle restraint system system installed on the road to provide a level of containment for an errant vehicle 4.3 safety barrier continuous vehicle restraint system installed alongside, or on the central reserve, of a road
NOTE This can include a vehicle parapet. 4.4 terminal end treatment of a safety barrier 4.5 transition connection of two safety barriers of different designs and/or performances SIST EN 1317-1:2010
EN 1317-1:2010 (E) 8 4.6 vehicle parapet
safety barrier installed on the side of a bridge or on a retaining wall or similar structure where there is a vertical drop and which can include additional protection and restraint for pedestrians and other road users (combined vehicle/pedestrian parapet) 4.7 crash cushion road vehicle energy absorption device installed in front of one or more hazards to reduce the severity of impact 4.8 pedestrian restraint system system installed to provide restraint for pedestrians 4.9 pedestrian parapet pedestrian or "other user" restraint system along the edge of a footway or footpath intended to restrain pedestrians and other users from stepping onto or crossing a road or other area likely to be hazardous NOTE "Other users" include provision for equestrians, cyclists and livestock. 4.10 kerb mass vehicle as delivered, including all fluids 4.11
test inertial mass kerb mass plus ballast and recording and brake equipment but excluding dummy 4.12 total mass mass that includes all items in the test vehicle at the beginning of the test 4.13 combined vehicle/pedestrian parapet vehicle parapet with additional safety provisions for pedestrians and/or other road users 4.14 wheel base distance between the centres of tyre contact of the two wheels on the same side of the vehicle, projected onto the longitudinal centreline of the vehicle NOTE For vehicles with more than two axles, the wheel bases between extreme axles. SIST EN 1317-1:2010
EN 1317-1:2010 (E) 9
Figure 2 — Examples of wheel base 4.15 wheel track distance between the centre of tyre contact of the two wheels of an axle, projected on to the YZ plane
NOTE In the case of dual wheels, it is the point centrally located between the centres of tyre contact of the two wheels of the dual axle.
Figure 3 — Examples of wheel track 4.16 centre of tyre contact P centre of tyre contact (or central plane between two tyres for dual axle vehicles) NOTE
See Figure 4. SIST EN 1317-1:2010
EN 1317-1:2010 (E) 10
Key A Wheel Spin Axis G Ground Plane M Wheel Mid Plane R Projection of A on G P Centre of Tyre Contract Figure 4 — Centre of tyre contact 4.17 anthropomorphic test device anthropomorphic device representative of a 50th percentile adult male, specifically designed to represent in form, size and mass, a vehicle occupant, and to reproduce the dynamic behaviour of an occupant in crash testing 4.18 removable barrier section section of a barrier connected at both ends to permanent barriers in order to be removed or displaced wholly or in parts that allows a horizontal opening to be provided 4.19 pre-tensioned system main longitudinal element(s) of a barrier pre-tensioned to obtain the design performance 5 Test methods 5.1 Test site The vehicle approach and exit box areas shall be generally flat with a gradient not exceeding 2,5 %. It shall have a level hardened paved surface and shall be clear of dust, debris, standing water, ice or snow at the time of the test. It shall be of sufficient size to enable the test vehicle to be accelerated up to the required speed and controlled so that its approach to and exit from the vehicle restraint system is stable. Dimensioned sketch plan(s) of the test area shall be included in the test report which shall show the testing area including the road restraint product tested, position of all cameras, path of the vehicle, impact point and the dimensioned locations for all test item parts exceeding 2,0 kg that broke away during the test. For tests which have been performed prior to EN 1317-1:2010, such dimensioned sketch plans are not obligatory. SIST EN 1317-1:2010
EN 1317-1:2010 (E) 11 During certain tests, such as a vehicle parapet test, where a bridge deck installation is used, the test vehicle and/or barrier shall not in any way touch or take advantage of structures which will not be present on the final bridge installation; i.e. if the vehicle drops down behind the bridge installation, it shall not touch soil or supporting devices. The dimensions of the edge detail shall be sufficient to demonstrate the actual performance of the vehicle and the tested system on the edge of a bridge, or structure. The test shall demonstrate the minimum width of structure behind the traffic face of the vehicle parapet that is required to safely contain and redirect the vehicle. For tests in accordance with EN 1317-2, EN 1317-3 or ENV 1317-4, the paved area shall be sufficient to allow the vehicle exit characteristics to be evaluated. Appropriate measures shall be taken in order to minimise dust generation from the test area and the test vehicle during the impact test so that photographic records will not be obscured. Appropriate measures shall be taken to ensure that in the exit area the test vehicle does not collide with any independent obstruction which could cause additional deformation of the test vehicle thereby precluding the accurate measurement of the vehicle cockpit deformation index (VCDI) (see 8.2). Foundations, anchorages and fixings shall perform according to the design of the vehicle restraint system. The vehicle restraint system's manufacturer shall provide details of the maximum forces which can be transmitted by anchorages to the foundation. Such maximum forces shall be those generated at the ultimate failure of the vehicle restraint system including vehicle parapet by any conceivable impact, and shall normally be greater than those that can be measured during the impact. Hence the ultimate forces which can be transmitted to the bridge deck shall be obtained by calculations or by ad-hoc tests. The forces on anchorages or on the bridge may be measured during the test and reported in 5.2 of the test report. 5.2 Test vehicles 5.2.1 General The vehicles to be used in the tests shall be production models and, for vehicles up to and including 1 500 kg, shall be representative of current traffic in Europe. All vehicles used for impact testing to this standard shall have characteristics and dimensions within the vehicle specifications defined in Table 1. The tyres shall be inflated to the vehicle manufacturer's recommended pressures. The condition of the vehicle shall satisfy the requirements for the issue of a vehicle certificate of road worthiness with respect to tyres, suspension, wheel alignment and bodywork. No repairs or modifications, including reinforcement, shall be made that would alter the general characteristics of the vehicle or invalidate such a certification. Any repairs shall conform to the original vehicle specification as defined by the vehicle manufacturer. The vehicle shall be clean and mud or deposits, which may cause dust on impact shall be removed prior to testing. Marker points shall be placed on external surfaces of the test vehicle to aid analysis. The vehicle shall not be restrained by the control of the steering or any other means during impact and whilst the vehicle is in the exit area (e.g. engine power, braking, anti lock brakes, blocking or fixing). 5.2.2 Loading conditions All fluids shall be included in the test inertial mass. All ballast weights shall be securely fixed to the vehicle in such a way as not to exceed the manufacturer's specifications for distribution of weight in the horizontal and vertical planes. SIST EN 1317-1:2010
EN 1317-1:2010 (E) 12 Ballast weights shall not be fixed in locations, which would modify the deformation of, or intrusions into, the vehicle. The permissible axle weights of the vehicles shall not be exceeded when loaded. Vehicle specifications under test conditions shall be as specified in Table 1. Table 1 — Vehicle specifications
MASS kg ±±±±
900 ±±±± 40
1 300 ±±±± 65
1 500 ±±±± 75
10 000 ±±±± 300
13 000 ±±±± 400
16 000 ±±±± 500
30 000 ±±±± 900
38 000 ±±±± 1 100
Test inertial massa
825 ±±±± 40 1 300 ±±±± 65 1 500 ±±±± 75 10 000 ±±±± 300 13 000 ±±±± 400 16 000 ±±±± 500 30 000 ±±±± 900 38 000 ±±±± 1 100 Including maximum ballastb
100 160 180 Not applicable Not applicable Not applicable Not applicable Not applicable ATD installed
78 ± 4 Not required
Not required Not required Not required Not required Not required DIMENSIONS m (Limit deviation ± 15 %)
Wheel track (front and rear) 1,35 1,40 1,50 2,00 2,00 2,00 2,00 2,00 Wheel radius (unloaded) Not applicable Not applicable Not applicable 0,46 0,52 0,52 0,55 0,55 Wheel base (between extreme axles) Not applicable Not applicable Not applicable 4,60 6,50 5,90 6,70 11,25 CENTRE OF MASS LOCATIONc d
Longitudinal distance from front axle (CGX) ± 10 % 0,90 1,10 1,24 2,70 3,80 3,10 4,14 6,20 Lateral distance from vehicle centre line (CGY) ± 0,07 ± 0,07 ± 0,08 ± 0,10 ± 0,10 ± 0,10 ± 0,10 ± 0,10 Height above ground (CGZ):
Vehicle mass (± 10 %) 0,49 0,53 0,53 Not applicable Not applicable Not applicable Not applicable Not applicable Load (+ 15 %, - 5 %) Not applicable Not applicable Not applicable 1,50 1,40 1,60 1,90 1,90 TYPE OF VEHICLE Car Car Car Rigid HGV Bus
Rigid HGV Rigid HGV Articulated HGV Number of axlese
1S + 1
1S + 1 1S + 1 1S + 1 1S + 1 1S + 1/2 2S + 2 1S + 3/4 a Including load for heavy goods vehicles (HGV). b Including measuring and recording equipment. c The vehicle’s centre of mass shall be determined when the ATD is not in the car. d The centre of mass of vehicles with two axles shall be determined in conformity with ISO 10392. e S: steering axle.
SIST EN 1317-1:2010
EN 1317-1:2010 (E) 13 6 Vehicle Instrumentation 6.1 Vehicle Instrumentation required for the calculation of ASI and THIV The vehicle shall be fitted with, as a minimum, one accelerometer for measurement in the longitudinal (forward) direction, one for the lateral (sideways) direction, one for the vertical direction (downward) and optionally an angular velocity sensor (rate sensor). The accelerometers shall be mounted at a single point (P) on the tunnel close to the vertical projection of vehicle centre of mass of the undeformed vehicle, but no further than 70 mm longitudinally and 40 mm laterally from the centre of mass. Measurements made before EN 1317-1:2010, with accelerometers fixed to an installation close to the centre of mass are accepted. Experience shows that, due to physical constraints, the actual placement of the set of accelerometers may be offset more than 70 mm from the centre of mass; then, significant differences can occur between measured accelerations and those at the centre of mass, due to angular motions. In these cases a second set of accelerometers shall be placed along the longitudinal axis and the process outlined in 6.3 shall be implemented. Yaw angle shall be measured within a tolerance of ± 4°, by integration of yaw rate or by other means. The sampling interval shall not exceed 50 ms. The yaw rate sensor shall be mounted in any rigid location, since the angular rates are the same in any point of a rigid body. 6.2 Frequency requirements The transducers, filters and recording channels shall comply with the frequency class specified in Clause 7; that is a frequency class of CFC_180 for acceleration and angular velocity channels. (Data filtered to CFC_60 may be used for graphical plotting of acceleration data.) They shall also conform to ISO 6487. This filter specification implies that the data shall be sampled at a sampling interval of at least 2 kHz. Since the data will be filtered by recursive (Butterworth) filters, more data should be collected than is specifically required by the analysis. A recursive filter always produces "starting transients" at the beginning and end of the data, and requires time to "settle down". An additional 500 ms of data shall be collected at the beginning and end of the data; this extra data can then be discarded after filtering. As well as specifying the sampling rate and filter frequency, the channel amplitude class (CAC) for each of the accelerometers and the rate gyro shall be specified, to ensure that the outputs from transducers and the recording system are not "clipped", while still producing maxima which are a reasonable fraction of "full scale", to avoid excessive "quantisation" in the digitising process. Suitable values of CAC shall be selected after inspection of a range of test data and reported in the test report. An event indicator shall be used to signal the moment of first vehicle contact with the vehicle restraint system. 6.3 Compensation for instrumentation displaced from the vehicle centre of mass Vehicular accelerations shall be used in the assessment of test results through ASI, THIV and the flail space model. The set of accelerometers should be placed as close as possible to the vehicle centre of mass (point P) but no further than 70 mm longitudinally and 40 mm laterally from the centre of mass. However experience shows that this cannot always be done, due to physical constraints within the vehicle. As a result, actual placement of the set of accelerometers can be offset more than 70 mm from the centre of mass; then, depending on the offset, significant differences can occur between measured accelerations