Council Directive 70/157/EEC of 6 February 1970 on the approximation of the laws of the Member States relating to the permissible sound level and the exhaust system of motor vehicles
Modified by
  • Actconcerning the Conditions of Accession and the Adjustments to the Treaties, 172B, March 27, 1972
  • Commission Directiveof 7 November 1973adapting to technical progress the Council Directive of 6 February 1970 on the approximation of the laws of the Member States relating to the permissible sound level and the exhaust system of motor vehicles(73/350/EEC), 373L0350, November 22, 1973
  • Council Directiveof 8 March 1977amending Directive 70/157/EEC relating to the permissible sound level and the exhaust system of motor vehicles(77/212/EEC), 377L0212, March 12, 1977
  • Commission Directiveof 13 April 1981adapting to technical progress Council Directive 70/157/EEC on the approximation of the laws of the Member States relating to the permissible sound level and the exhaust system of motor vehicles(81/334/EEC), 381L0334, May 18, 1981
  • Commission Directiveof 3 July 1984adapting to technical progress Council Directive 70/157/EEC on the approximation of the laws of the Member States relating to the permissible sound level and the exhaust system of motor vehicles(84/372/EEC), 384L0372, July 26, 1984
  • Council directiveof 3 September 1984amending Directive 70/157/EEC on the approximation of the laws of the Member States relating to the permissible sound level and the exhaust system of motor vehicles(84/424/EEC), 384L0424, September 6, 1984
  • Actconcerning the conditions of accession of the Kingdom of Spain and the Portuguese Republic and the adjustments to the Treaties, 185I, November 15, 1985
  • Council Directiveof 25 June 1987amending certain directives on the approximation of the laws of the Member States relating to industrial products with respect to the distinctive numbers and letters indicating the Member States(87/354/EEC), 387L0354, July 11, 1987
  • Commission Directiveof 17 July 1989adapting to technical progress Council Directives 70/157/EEC, 70/220/EEC, 72/245/EEC, 72/306/EEC, 80/1268/EEC and 80/1269/EEC relating to motor vehicles(89/491/EEC), 389L0491, August 15, 1989
  • Council Directive 92/97/EECof 10 November 1992amending Directive 70/157/EEC on the approximation of the laws of the Member States relating to the permissible sound level and the exhaust system of motor vehicles, 392L0097, December 19, 1992
  • Actconcerning the conditions of accession of the Kingdom of Norway, the Republic of Austria, the Republic of Finland and the Kingdom of Sweden and the adjustments to the Treaties on which the European Union is founded(94/C 241/08) Decision of the Council of the European Unionof 1 January 1995adjusting the instruments concerning the accession of new Member States to the European Union(95/1/EC, Euratom, ECSC), 194N395D0001, August 29, 1994
  • Decision of the Council of the European Unionof 1 January 1995adjusting the instruments concerning the accession of new Member States to the European Union(95/1/EC, Euratom, ECSC), 395D0001, January 1, 1995
  • Commission Directive 96/20/ECof 27 March 1996adapting to technical progress Council Directive 70/157/EEC relating to the permissible sound level and the exhaust system of motor vehicles(Text with EEA relevance), 396L0020, April 13, 1996
  • Commission Directive 1999/101/ECof 15 December 1999adapting to technical progress Council Directive 70/157/EEC relating to the permissible sound level and the exhaust system of motor vehicles(Text with EEA relevance), 399L0101, December 28, 1999
  • Actconcerning the conditions of accession of the Czech Republic, the Republic of Estonia, the Republic of Cyprus, the Republic of Latvia, the Republic of Lithuania, the Republic of Hungary, the Republic of Malta, the Republic of Poland, the Republic of Slovenia and the Slovak Republic and the adjustments to the Treaties on which the European Union is founded, 103T, September 23, 2003
  • Council Directive 2006/96/ECof 20 November 2006adapting certain Directives in the field of free movement of goods, by reason of the accession of Bulgaria and Romania, 306L0096, December 20, 2006
  • Commission Directive 2007/34/ECof 14 June 2007amending, for the purposes of its adaptation to technical progress, Council Directive 70/157/EEC concerning the permissible sound level and the exhaust system of motor vehicles(Text with EEA relevance), 307L0034, June 15, 2007
Council Directiveof 6 February 1970on the approximation of the laws of the Member States relating to the permissible sound level and the exhaust system of motor vehicles(70/157/EEC) THE COUNCIL OF THE EUROPEAN COMMUNITIES, Having regard to the Treaty establishing the European Economic Community, and in particular Article 100 thereof; Having regard to the proposal from the Commission; Having regard to the Opinion of the European ParliamentOJ No C 160, 18.12.1969, p. 7.; Having regard to the Opinion of the Economic and Social CommitteeOJ No C 48, 16.4.1969, p. 16.; Whereas the technical requirements which motor vehicles must satisfy pursuant to national laws relate, inter alia, to the permissible sound level and the exhaust system; Whereas those requirements differ from one Member State to another; whereas it is therefore necessary that all Member States adopt the same requirements either in addition to or in place of their existing rules, in order, in particular, to allow the EEC type approval procedure which was the subject of the Council DirectiveOJ No L 42, 23.2.1970, p. 1. of 6 February 1970 on the approximation of the laws of the Member States relating to the type approval of motor vehicles and their trailers to be applied in respect of each type of vehicle; HAS ADOPTED THIS DIRECTIVE:
Article 1 For the purposes of this Directive, "vehicle" means any motor vehicle intended for use on the road, with or without bodywork, having at least four wheels and a maximum design speed exceeding 25 kilometres per hour, with the exception of vehicles which run on rails and of agricultural and forestry tractors and all mobile machinery.
Article 2 No Member State may, on grounds relating to the permissible sound level and the exhaust system, refuse to grant EEC or national type-approval in respect of a type of motor vehicle or type of exhaust system or component of such a system regarded as a separate technical unit, if the vehicle satisfies the requirements of Annex I as regards the sound level and exhaust system, if the exhaust system or any component thereof, considered as a separate technical unit within the meaning of Article 2 of Directive 70/156/EEC satisfies the requirements of Annex II.
Article 2a 1. No Member State may, on grounds relating to the permissible sound level and the exhaust system, refuse or prohibit the sale, registration, entry into service or use of any vehicle in which the sound level and the exhaust system satisfy the requirements of Annex I. 2. No Member State may, on grounds relating to the permissible sound level and the exhaust system, prohibit the placing on the market of an exhaust system or any component thereof considered as a separate technical unit within the meaning of Article 2 of Directive 70/156/EEC if, within the meaning of Article 2, it is of a type in respect of which a type-approval has been granted.
Article 3 The amendments necessary for adjusting the requirements of the Annexes so as to take account of technical progress, with the exception of the requirements set out under items 5.2.2.1 and 5.2.2.5 of Annex I, shall be adopted in accordance with the procedure laid down in Article 13 of the Council Directive on the type approval of motor vehicles and their trailers.
Article 4 1. Member States shall put into force the provisions containing the requirements needed in order to comply with this Directive within eighteen months of its notification and shall forthwith inform the Commission thereof. 2. Member States shall ensure that the texts of the main provisions of national law which they adopt in the field covered by this Directive are communicated to the Commission.
Article 5 This Directive is addressed to the Member States.
null List of Annexes
ANNEX I: Provisions for ec type-approval in respect of the sound level of a type of motor vehicle Appendix 1Information document Appendix 2Model Addendum to EC type-approval certificateconcerning the type-approval of a vehicle with regard to Directive 70/157/EEC as last amended by Directive …/…/EC
ANNEX II: Administrative provisions for ec type-approval of exhaust systems as separate technical units (replacement exhaust systems) Appendix 1Information document Appendix 2Model Addendum to EC type-approval certificateconcerning the separate technical unit type-approval of exhaust systems for motor vehicles with regard to Directive 70/157/EEC as last amended by Directive …/…/EC Appendix 3Model for the EC type-approval mark
ANNEX III: Checks on conformity of production
ANNEX IV: Test track specifications
ANNEX I PROVISIONS FOR EC TYPE-APPROVAL IN RESPECT OF THE SOUND LEVEL OF A TYPE OF MOTOR VEHICLE 1.APPLICATION FOR EC TYPE-APPROVAL OF A VEHICLE TYPE 1.1. The application for EC type-approval pursuant to Article 3(4) of Directive 70/156/EEC of a vehicle type with regard to its sound level shall be submitted by the vehicle manufacturer. 1.2. A model for the information document is given in Appendix 1. 1.3. A vehicle representative of the type in respect of which type-approval is sought must be submitted to the technical service responsible for the tests by the vehicle manufacturer. 1.4. At the request of the technical service, a specimen of the exhaust system and an engine of at least the same cylinder capacity and rated maximum power as that fitted to the vehicle in respect of which type-approval is sought must also be submitted. 2.SOUND LEVEL OF MOVING VEHICLES 2.1.Limiting values The sound level measured in accordance with the provisions of Annex III shall not exceed the following limits:
2.1.2.Vehicles intended for the carriage of passengers and equipped with more than nine seats, including the driver's seat; and having a maximum permissible mass of more than 3,5 tonnes and: 2.1.3.Vehicles intended for the carriage of passengers and equipped with more than nine seats, including the driver's seat; vehicles intended for the carriage of goods: 2.1.4.Vehicles intended for the carriage of goods and having a maximum permissible mass exceeding 3,5 tonnes:
Vehicle categories Values expressed in dB(A)(decibels(A))
2.1.1.Vehicles intended for the carriage of passengers, and comprising not more than nine seats including the driver's seat 74
2.1.2.1.with an engine power of less than 150 kW 78
2.1.2.2.with an engine power of not less than 150 kW 80
2.1.3.1.with a maximum permissible mass not exceeding 2 tonnes 76
2.1.3.2.with a maximum permissible mass exceeding 2 tonnes but not exceeding 3,5 tonnes 77
2.1.4.1.with an engine power of less than 75 kW 77
2.1.4.2.with an engine power of not less than 75 kW but less than 150 kW 78
2.1.4.3.with an engine power of not less than 150 kW 80
However for vehicles of categories 2.1.1 and 2.1.3, the limit values are increased by 1 dB(A) if they are equipped with a direct injection diesel engine, for vehicles with a maximum permissible mass of over two tonnes designed for off-road use, the limit values are increased by 1 dB(A) if their engine power is less than 150 kW and 2 dB(A) if their engine power is 150 kW or more, for vehicles in category 2.1.1, equipped with a manually operated gear box having more than four forward gears and with an engine developing a maximum power exceeding 140 kW/t and whose maximum power/maximum mass ratio exceeds 75 kW/t, the limit values are increased by 1 dB(A) if the speed at which the rear of the vehicle passes the line BB' in third gear is greater than 61 km/h.
2.2.Interpretation of results 2.2.1. To take account of inaccuracies in the measuring instruments, the result obtained from each measurement is determined by deducting 1 dB(A) from the meter reading. 2.2.2. The measurements are considered valid if the difference between two consecutive measurements on the same side of the vehicle does not exceed 2 dB(A). 2.2.3. The highest sound level measured shall constitute the test result. Should the result exceed the maximum permissible sound level for the category of vehicle tested by 1 dB(A), two further measurements shall be made at the corresponding microphone position. Three of the four measurements thus obtained at that microphone position must fall within the prescribed limits.
3.MARKINGS 3.1. The exhaust and intake system components, excluding fixing hardware and pipes, must bear: 3.1.1. the trade mark or name of the manufacturer of the systems and their components; 3.1.2. the manufacturer's trade description. 3.2. These markings must be clearly legible and indelible, even when the system is fitted to the vehicle. 4.GRANTING OF EC TYPE-APPROVAL OF A VEHICLE TYPE 4.1. If the relevant requirements are satisfied, EC type-approval pursuant to Article 4(3) and, if applicable, 4(4) of Directive 70/156/EEC shall be granted. 4.2. A model for the EC type-approval certificate is given in Appendix 2. 4.3. An approval number in accordance with Annex VII to Directive 70/156/EEC shall be assigned to each vehicle type approved. The same Member State shall not assign the same number to another vehicle type. 5.MODIFICATIONS OF THE TYPE AND AMENDMENTS TO APPROVALS 5.1. In the case of modifications of the type approved pursuant to this Directive, the provisions of Article 5 of Directive 70/156/EEC shall apply. 6.CONFORMITY OF PRODUCTION 6.1. Measures to ensure the conformity of production shall be taken in accordance with the requirements laid down in Article 10 of Directive 70/156/EEC. 6.2. Special provisions: 6.2.1. The tests referred to in item 2.3.5 of Annex X to Directive 70/156/EEC are those laid down in Annex 7 of UN/ECE Regulation No 51 as referred to in Annex III of this Directive. 6.2.2. The frequency of inspections referred to in item 3 of Annex X to Directive 70/156/EEC is normally one every two years.
ANNEX II ADMINISTRATIVE PROVISIONS FOR EC TYPE-APPROVAL OF EXHAUST SYSTEMS AS SEPARATE TECHNICAL UNITS (REPLACEMENT EXHAUST SYSTEMS) 1.APPLICATION FOR EC TYPE-APPROVAL 1.1. The application of EC type-approval pursuant to Article 3(4) of Directive 70/156/EEC in respect of a replacement exhaust system or component thereof as a separate technical unit shall be submitted by the vehicle manufacturer or the manufacturer of the separate technical unit in question. 1.2. A model for the information document is given in Appendix 1. 1.3. At the request of the technical service concerned, the applicant must submit: 1.3.1. two examples of the system in respect of which application for EC type-approval has been made, 1.3.2. an exhaust system of the type originally fitted to the vehicle when EC type-approval was granted, 1.3.3. a vehicle representative of the type to which the system is to be fitted, which meets the requirements of item 4.1 of Annex 7 of UN/ECE Regulation No 51 as referred to in Annex III of this Directive. 1.3.4. a separate engine corresponding to the type of vehicle described above. 2.MARKINGS 2.4.1. The replacement exhaust system or its components, excluding fixing hardware and pipes must bear: 2.4.1.1. the trademark or trade name of the manufacturer of the replacement system and its components, 2.4.1.2. the manufacturer's trade description, 2.4.2. These marks must be clearly legible and indelible, even when the system is fitted to the vehicle. 3.GRANTING OF EC TYPE-APPROVAL 3.1. If the relevant requirements are satisfied, EC type-approval pursuant to Article 4(3) and, if applicable, Article 4(4) of Directive 70/156/EEC shall be granted. 3.2. A model for the EC type-approval certificate is given in Appendix 2. 3.3. A type-approval number in accordance with Annex VII to Directive 70/156/EEC shall be assigned to each type of replacement exhaust system or component thereof approved as a separate technical unit; section 3 of the type-approval number shall indicate the number of the amending Directive which was applicable at the time of the vehicle type-approval. The same Member State shall not assign the same number to another type of replacement exhaust system or component thereof. 4.EC TYPE-APPROVAL MARK 4.1. Every replacement exhaust system or component thereof, excluding fixing hardware and pipes, conforming to a type approved under this Directive shall bear an EC type-approval mark. 4.2. The EC type-approval mark shall consist of a rectangle surrounding the lower case letter "e" followed by the distinguishing letter(s) or number of the Member State which has granted the approval: "1" for Germany "2" for France "3" for Italy "4" for the Netherlands "5" for Sweden "6" for Belgium "7" for Hungary "8" for the Czech Republic "9" for Spain "11" for the United Kingdom "12" for Austria "13" for Luxembourg "17" for Finland "18" for Denmark "19" for Romania "20" for Poland "21" for Portugal "23" for Greece "24" for Ireland "26" for Slovenia "27" for Slovakia "29" for Estonia "32" for Latvia "34" for Bulgaria "36" for Lithuania "49" for Cyprus "50" for Malta It must also include in the vicinity of the rectangle the "base approval number" contained in section 4 of the type-approval number referred to in Annex VII to Directive 70/156/EEC, preceded by the two figures indicating the sequence number assigned to the most recent major technical amendment to Council Directive 70/157/EEC which was applicable at the time of the vehicle type-approval. For Directive 70/157/ EEC, the sequence number is 00; for Directive 77/212/EEC the sequence number is 01; for Directive 84/424/EEC the sequence number is 02; for Directive 92/97/EEC and this Directive the sequence number is 03. Sequence number 03 reflects as well the technical requirements of the 00 series of amendments of UN/ECE Regulation No 59. 4.3. The mark must be clearly legible and indelible even when the replacement exhaust system or component thereof is fitted to the vehicle. 4.4. An example of the EC type-approval mark is shown in Appendix 3. 5.MODIFICATION OF THE TYPE AND AMENDMENTS TO APPROVALS 5.1. In the case of modifications of the type approved pursuant to this Directive, the provisions of Article 5 of Directive 70/156/EEC shall apply. 6.CONFORMITY OF PRODUCTION 6.1. Measures to ensure the conformity of production shall be taken in accordance with the requirements laid down in Article 10 to Directive 70/156/EEC. 6.2. Special provisions: 6.2.1. The tests referred to item 2.3.5 of Annex X to Directive 70/156/EEC are those prescribed in Annex 5 of UN/ECE Regulation No 59 as referred to in Annex III of this Directive. 6.2.2. The frequency of inspections referred to in item 3 of Annex X to Directive 70/156/EEC is normally one every two years. ANNEX III MODELMaximum size: A4 (210 × 297 mm)01970L0157-20070705_en_img_1 ANNEX IV MODELMaximum size: A4 (210 × 297 mm) ANNEX III 1.The technical requirements are those set out in: (a)points 2, 6.1, 6.2.1 and 6.3 of UN/ECE Regulation No 51OJ L 137, 30.5.2007, p. 68. and Annexes 3 to 10 thereto; (b)points 2 and 6 of UN/ECE Regulation No 59OJ L 326, 24.11.2006, p. 43. and Annexes 3 to 5 thereto. 2.For the purposes of the application of the provisions referred to in point 1, the following shall apply: (a)"Unladen vehicle" means a vehicle the mass of which is described in point 2.6 of Appendix 1 of Annex I to this Directive, without driver; (b)"Communication form" shall be understood as type-approval-certificate set out in Appendix 2 of Annexes I and II; (c)"Contracting Parties to the respective regulations" shall be understood as Member States; (d)references to Regulation No 51 and Regulation No 59 shall be construed as references to Directive 70/157/EEC; (e)footnote 1 in point 2.2.6 shall be understood as follows: "For definitions of the categories, see Annex II A to Directive 70/156/EEC". ANNEX IV TEST TRACK SPECIFICATIONSThis Annex lays down specifications relating to the physical characteristics of the paving and the layout of the test track paving. 1.REQUIRED CHARACTERISTICS OF THE SURFACE A surface is considered to conform to this Directive provided that the texture and voids content or sound absorption coefficient have been measured and found to fulfill all the requirements given in 1.1 to 1.4 and provided that the design requirements (Section 2.2) have been met. 1.1.Residual voids content The residual voids content, Vc, of the test track paving mixture shall not exceed 8 %. See section 3.1 for measurement procedure. 1.2.Sound absorption coefficient If the surface fails to comply with the residual voids content requirement, the surface is acceptable only if its sound absorption coefficient, α, is ≤ 0,10. See section 3.2 for measurement procedure.The requirement of section 1.1. and 1.2. is met also if only sound absorption has been measured and found to be: α ≤ 0,10. 1.3.Texture depth The texture depth (TD) measured according to the volumetric method (see section 3.3) shall be:TD ≥ 0,4 mm. 1.4.Homogeneity of the surface Every practical effort shall be taken to ensure that the surface is made to be as homogenous as possible within the test area. This includes the texture and voids content, but it should also be observed that if the rolling process results in more effective rolling at some places than at others, the texture may be different and uneveness causing bumps may also occur. 1.5.Period of testing In order to check whether the surface continues to conform to the texture and voids content or sound absorption requirements stipulated in this standard, periodic testing of the surface shall be done at the following intervals: (a)for residual voids content or sound absorption: when the surface is new, if the surface meets the requirement when new, no further periodical testing is required.If it does not meet the requirement when it is new, it may do so later because surfaces tend to become clogged and compacted with time; (b)for texture depth (TD): when the surface is new, when the noise testing starts (NB: not before four weeks after laying), then every twelve months. 2.TEST SURFACE DESIGN 2.1.Area When designing the test track layout it is important to ensure that, as a minimum requirement, the area traversed by the vehicles running through the test strip is covered with the specified test material with suitable margins for safe and practical driving. This will require that the width of the track is at least 3 m and the length of the track extends beyond lines AA and BB by at least 10 m at either end. Figure 1 shows a plan of a suitable test site and indicates the minimum area which shall be machine laid and machine compacted with the specified test surface material. The shaded part is called "test area" 2.2.Design requirements for the surface The test surface shall meet four design requirements: 1.it shall be a dense asphaltic concrete; 2.the maximum chipping size shall be 8 mm (tolerances allow from 6,3 to 10 mm); 3.the thickness of the wearing course shall be ≥ 30 mm; 4.the binder shall be a straight penetration grade bitumen without modification. As a guide to the test surface constructor, an aggregate grading curve which will give desired characteristics is shown in figure 2. In addition, table 3 gives some guidelines in order to obtain the desired texture and durability. The grading curve fits the following formula: where dsquare mesh sieve size, in mm dmax8 mm for the mean curve dmax10 mm for the lower tolerance curve dmax6,3 mm for the upper tolerance curve In addition to the above, the following recommendations are given: the sand fraction (0,063 mm < square mesh sieve size < 2 mm) shall include no more than 55 % natural sand and at least 45 % crushed sand, the base and sub-base shall ensure a good stability and evenness, according to best road construction practice, the chippings shall be crushed (100 % crushed faces) and of a material with a high resistance to crushing, the chippings used in the mix shall be washed, no extra chippings shall be added on to the surface, the binder hardness expressed as PEN value shall be 40 to 60, 60 to 80 or even 80 to 100, depending on the climatic conditions of the country. The rule is that as hard a binder as possible shall be used, provided this is consistent with common practice, the temperature of the mix before rolling shall be chosen so as to achieve by subsequent rolling the required voids content. In order to increase the probability of satisfying the specifications of sections 1.1 to 1.4, the compactness shall be studied not only by an appropriate choice of mixing temperature, but also by an appropriate number of passings and by the choice of compacting vehicle.
Table 3 Design guidelines
Target values Tolerances
By total mass of mix By mass of the apprecate
Mass of stones, Square Mesh Sieve (SM)> 2 mm 47,6 % 50,5 % ±5
Mass of sand 0,063 < SM < 2 mm 38,0 % 40,2 % ±5
Mass of filler SM < 0,063 mm 8,8 % 9,3 % ±2
Mass of binder (bitumen) 5,8 % N.A. ±0,5
Maximum chipping size 8 mm 6,3—10
Binder hardness (see below)
Polished stone value (PSV) (see doc. 5 in bibliography) > 50
Compactness, relative to Marshall compactness 98 %
3.TEST METHODS 3.1.Measurement of the residual voids content For the purpose of this measurement, cores have to be taken from the track at least at four different positions which are equally distributed in the test area between lines AA and BB (see figure 1). In order to avoid inhomogeneity and unevenness in the wheel tracks, cores should not be taken in the wheel tracks themselves, but close to them. Two cores (minimum) should be taken close to the wheel tracks and one core (minimum) should be taken approximately midway between the wheel tracks and each microphone location.If there is a suspicion that the condition of homogeneity is not met (see section 1.4), cores shall be taken from more locations within the test area.The residual voids content has to be determined for each core. Then the average value from all cores shall be calculated and compared with the requirement of section 1.1. In addition, no single core shall have a voids value which is higher than 10 %.The test surface constructor is reminded of the problem which may arise when the test area is heated by pipes or electrical wires and cores must be taken from this area. Such installations must be carefully planned with respect to future core drilling locations. It is recommended to leave a few locations of size approximately 200 × 300 mm where there are no wires or pipes, or where the latter are located deep enough in order not to be damaged by cores taken from the surface layer. 3.2.Sound absorption coefficient The sound absorption coefficient (normal incidence) shall be measured by the impedance tube method using the procedure specified in ISO/DIS 10534: "Acoustics — Determination of sound absorption coefficient and impedance by a tube method".Regarding test specimens, the same requirements shall be followed as regarding the residual voids content (see section 3.1).The sound absorption shall be measured in the range 400 to 800 Hz and in the range 800 to 1600 Hz (at least at the centre frequencies of third octave bands) and the maximum values shall be identified for both of these frequency ranges. Then these values, for all test cores, shall be averaged to constitute the final result. 3.3.Volumetric macrotexture measurement For the purposes of this standard, texture depth measurements shall be made on at least 10 positions evenly spaced along the wheel tracks of the test strip and the average value taken to compare with the specified minimum texture depth. See Annex F to Draft Standard ISO/DIS 10844 for a description of the procedure. 4.STABILITY IN TIME AND MAINTENANCE 4.1.Age influence In common with many other surfaces, it is expected that the tyre/road noise levels measured on the test surface may increase slightly during the first six to 12 months after construction.The surface will achieve its required characteristics not earlier than four weeks after construction. The influence of age on the noise from trucks is generally less than that from cars.The stability over time is determined mainly by the polishing and compaction by vehicles driving on the surface. It shall be periodically checked as stated in section 1.5. 4.2.Maintenance of the surface Loose debris or dust which could significantly reduce the effective texture depth must be removed from the surface. In countries with winter climates, salt is sometimes used for de-icing. Salt may alter the surface temporarily or even permanently in such a way as to increase noise and is therefore not recommended. 4.3.Repaving the test area If it is necessary to repave the test track, it is usually unnecessary to repave more than the test strip (of 3 m width in figure 1) where vehicles are driving provided the test area outside the strip met the requirement of residual voids content or sound absorption when it was measured. 5.DOCUMENTATION OF THE SURFACE AND OF TESTS PERFORMED ON IT 5.1.Documentation of the test surface The following data shall be given in a document describing the test surface: (a)the location of the test track; (b)type of binder, binder hardness, type of aggregate, maximum theoretical density of the concrete ("DR"), thickness of the wearing course and grading curve determined from cores from the test track; (c)method of compaction (e.g. type of roller, roller mass, number of passes); (d)temperature of the mix, temperature of the ambient air and wind speed during laying of the surface; (e)date when the surface was laid and contractor; (f)all or at least the latest test result, including: (i)the residual voids content of each core; (ii)the locations in the test area from where the cores for voids measurement have been taken; (iii)the sound absorption coefficient of each core (if measured). Specify the results both for each core and each frequency range as well as the overall average; (iv)the locations in the test area from where the cores for absorption measurement have been taken; (v)texture depth, including the number of tests and standard deviation; (vi)the institution responsible for tests (i) and (iii) and the type of equipment used; (vii)date of the test(s) and date when the cores were taken from the test track. 5.2.Documentation of vehicle noise tests conducted on the surface In the document describing the vehicle noise test(s) it shall be stated whether all the requirments were fulfilled or not. Reference shall be given to a document according to section 5.1.