ANNEX 3

METHODS AND INSTRUMENTS FOR MEASURING THE SOUND EMITTED BY L2, L4 AND L5 CATEGORY VEHICLES

1. MEASURING INSTRUMENTS

1.1. General

The apparatus used for measuring the sound pressure level shall be a sound level meter or equivalent measuring system meeting the requirements of Class 1 instruments (inclusive of the recommended windscreen, if used). These requirements are described in IEC 61672-1:2013. Measurements shall be carried out using the time weighting ‘F’ of the acoustic measuring instrument and the ‘A’ frequency weighting curve also described in IEC 61672-1:2013. When using a system that includes periodic monitoring of the A-weighted sound pressure level, a reading should be made at a time interval not greater than 30 ms. The instruments shall be maintained and calibrated in accordance with the instructions of the instrument manufacturer.

1.2. Calibration

At the beginning and at the end of every measurement session, the entire acoustic measuring system shall be checked by means of a sound calibrator that fulfils the requirements of Class 1 sound calibrators according to IEC 60942:2003. Without any further adjustment, the difference between the readings shall be less than or equal to 0,5 dB(A). If this value is exceeded, the results of the measurements obtained after the previous satisfactory check shall be discarded.

1.3. Compliance with requirements

Compliance of the sound calibrator with the requirements of IEC 60942:2003 shall be verified once a year. Compliance of the instrumentation system with the requirements of IEC 61672-1:2013 shall be verified at least every 2 years. All compliance testing shall be conducted by a laboratory which is authorised to perform calibrations traceable to the appropriate standards.

1.4. Instrumentation for speed measurements

The rotational speed of the engine shall be measured with an instrument meeting specification limits of at least ± 2 per cent or better at the engine speeds required for the measurements being performed.

The road speed of the vehicle shall be measured with instruments meeting specification limits of at least ± 0,5 km/h when using continuous measuring devices. If testing uses independent measurements of vehicle speed, this instrumentation shall meet specification limits of at least ± 0,2 km/h (1).

1.5. Meteorological instrumentation

The meteorological instrumentation used to monitor the environmental conditions during the test shall meet the following specifications:

± 1 °C or less for a temperature measuring device;

± 1,0 m/s for a wind speed measuring device;

± 5 hPa for a barometric pressure measuring device;

± 5 per cent for a relative humidity measuring device.

2. CONDITIONS OF MEASUREMENT

2.1. Test site, weather conditions and background noise level correction

2.1.1. Test site

The test site shall consist of a central acceleration track surrounded by a substantially level test area. The test track shall be level; the track surface shall be dry and so designed that tyre sound remains low.

On the test site, free sound field conditions shall be maintained to within ± 1 dB between the sound source placed in the middle of the acceleration section and the microphone. This condition shall be deemed to be met if there are no large sound-reflecting objects such as fences, rocks, bridges or buildings within 50 m of the centre of the acceleration section. The surface of the test track shall conform to the requirements of Annex 5 to this Regulation.

No obstacle likely to affect the sound field shall be close to the microphone and no one shall come between the microphone and the sound source. The observer taking the measurements shall take up position so as to avoid influencing the metre readings.

The surface of the test track shall conform to the requirements of Annex 5 to this Regulation or to ISO10844:2014. After the end of the period indicated in paragraph 11.8 of this Regulation only ISO 10844:2014 shall be used as reference.

2.1.2. Weather conditions and background noise correction

Measurements shall not be made in poor weather conditions. The tests shall not be carried out if the wind speed, including gusts, exceeds 5 m/s during the sound-measurement interval.

For measurement purposes, the weighted sound level (A) of sound sources other than on the test vehicle and the sound level produced by the effect of the wind shall be at least 10 dB(A) below the sound level produced by the vehicle. The microphone may be fitted with a suitable wind guard, provided that its influence on the sensitivity and directional characteristics of the microphone are taken into account.

If the difference between ambient noise and measured sound levels is between 10 and 15 dB(A), in order to calculate the test result, the appropriate correction shall be subtracted from the readings on the sound level meter, as given in Table 1.

Table 1

Correction applied to individual measured test value

Background sound pressure level difference to measured sound pressure level, in dB 10 11 12 13 14 ≥ 15 Correction, in dB(A) 0,5 0,4 0,3 0,2 0,1 0,0

2.2. Condition of the vehicle

2.2.1. General conditions

The vehicle shall be supplied as specified by the vehicle manufacturer.

Before the measurements are started, the vehicle shall be brought to its normal operating conditions as regards:

— Temperatures;

— Tuning;

— Fuel;

— Sparking plugs, carburettor(s), etc., (as appropriate).

If the vehicle is fitted with fans with an automatic actuating mechanism, this system shall not be interfered with during the sound measurements.

If the vehicle is equipped with devices which are not necessary for its propulsion, but which are used whilst the vehicle is in normal service on the road, those devices shall be in operation in accordance with the specifications of the manufacturer.

For vehicles having more than one driven wheel, only the drive provided for normal road operation may be used. If the vehicle is fitted with a trailer or a semi-trailer, this shall be removed for the purposes of the test.

2.2.2. Test mass of the vehicle

The vehicle shall be tested with its test mass as defined in paragraph 2.10 of this Regulation.

2.2.3. Tyre selection and condition

The tyres shall be appropriate for the vehicle and shall be inflated to the pressure recommended by the vehicle manufacturer for the test mass of the vehicle.

The tyres shall be selected by the vehicle manufacturer, and correspond to one of the tyre sizes and types designated for the vehicle by the vehicle manufacturer. The minimum tread depth shall be at least 80 per cent of the full tread depth.

3. METHODS OF MEASUREMENT

3.1. Measurement of the sound emission of the vehicles in motion

3.1.1. Test arrangement and microphone positions

3.1.1.1. The test arrangement is shown in Figure 1.

Two lines, AA′ and BB′, parallel to the microphone line PP′ and situated respectively 10 m forward and 10 m rearward of that line shall be marked out on the test track.

3.1.1.2. The distance of the microphone positions from the line CC′, on the microphone line PP′, perpendicular to the reference line CC′ on the test track (see Figure 1), shall be 7,5 ± 0,05 m.

The microphones shall be located 1,2 ± 0,02 m above the ground level. The reference direction for free-field conditions (see IEC 61672-1:2013) shall be horizontal and directed perpendicularly towards the path of the vehicle line CC′.

3.1.2. Acceleration test execution, approach vehicle speed and gear use

3.1.2.1. Acceleration test execution

The vehicle shall approach line AA′ at an initial steady vehicle speed vAA′ as specified below. When the front of the vehicle reaches line AA′ the accelerator handle shall be fully opened as quickly as practically possible and kept in that position until the rear of the vehicle reaches the line BB′; the accelerator handle shall then be returned as quickly as possible to the idle position. The vehicle speed achieved, when the rear of the vehicle reaches the line BB′ is called vBB′.

The engine speeds corresponding to vAA′ and vBB′ in a specific test condition are called nAA′ and nBB′.

In the case of articulated vehicles consisting of two non-separable units regarded as a single vehicle, the semi-trailer shall be disregarded in determining when line BB′ is crossed.

For all measurements, the vehicle shall be driven in a straight line along the test track in such a way that the track of the median longitudinal plane of the vehicle is as close as possible to the line CC′.

Figure 1

Measuring positions for vehicles in motion

3.1.2.2. Determination of the approach vehicle speed and the gear use

3.1.2.2.1. Vehicle with no gearbox

The vehicle shall approach line AA′ at a steady vehicle speed vAA′ corresponding either, in terms of engine speed, (min– 1) to 75 per cent of the rated engine speed as defined in paragraph 2.4 of this Regulation, or to 75 per cent of the maximum engine speed permitted by the governor, or to 50 km/h, whichever is the lowest.

3.1.2.2.2. Vehicles with manual transmissions, automatic transmissions, or transmissions with continuously variable transmission ratios (CVT's) tested with locked gears

If the vehicle is fitted with a dual mode transmission (e.g. low and high), the mode for normal on-road operation shall be selected.

If the vehicle is fitted with a gearbox with two or three or four forward gears or the same number of lockable gears in automatic transmission or in CVT, the second gear shall be used. If the gearbox has more than four forward gears or the same number of lockable gears in automatic transmission or in CVT, the third gear shall be used.

The vehicle shall approach line AA′ at a steady vehicle speed vAA′ corresponding either, in terms of engine speed, to 75 per cent of the rated engine speed as defined in paragraph 2.4 of this Regulation or to 75 per cent of the maximum engine speed permitted by the governor, or to 50 km/h, whichever is the lowest.

If, by following the above procedure, the engine speed nBB′, achieved when the rear of the vehicle passes the line BB′, exceeds the rated engine speed as defined in paragraph 2.4 of this Regulation, the first higher gear (or locked gear) which ensures that the rated engine speed is no longer exceeded up to the line BB′ of the measurement area should be used instead of the second or third gear.

Auxiliary step-up ratios (‘overdrive’) shall not be engaged.

3.1.2.2.3. Vehicles with automatic transmissions, adaptive transmissions or transmissions with variable transmission ratios tested with non-locked gears

The gear selector position for full automatic operation shall be used.

Where several full automatic operation modes are available (e.g. economic, sporty), that mode shall be selected which results in the highest average acceleration of the vehicle between lines AA′ and BB′.

The test may then include a gear change to a lower gear and a higher acceleration. A gear change to a higher gear and a lower acceleration is not allowed. In any case, a gear change to a gear which is typically not used at the specified condition in urban traffic shall be avoided.

Therefore, it is permitted to establish and use electronic or mechanical devices, including alternative gear selector positions, to prevent a downshift to a gear which is typically not used at the specified test condition in urban traffic. The functionality of the devices shall be described in the communication form.

The vehicle shall approach the line AA′ at a steady vehicle speed vAA′ of 50 km/h or at 75 per cent of its maximum vehicle speed as defined in paragraph 2.11 of this Regulation, whichever is the lower.

3.1.3. Sound level determination

The maximum sound level recorded at each side of the vehicle shall be reduced by 1 dB(A) to account for measurement inaccuracy and mathematically rounded to the nearest first decimal place (e.g. 78,45 shall be noted as to 78,5 while 78,44 shall be noted as to 78,4). These values constitute the results of the measurement.

The measurement will be invalid if an abnormal discrepancy is recorded between the peak value and the general sound level.

At least two measurements shall be made on each side of the vehicle.

The measurements shall be considered valid if the difference between the results of the two consecutive measurements on the same side of the vehicle is not more than 2 dB(A).

Preliminary measurements may be made for adjustment purposes, but shall be disregarded for the determination of the measurement results.

3.1.4. Calculation of the final test result

The final test result is the average of the four test results rounded off to the nearest whole decibel. If the figure following the decimal point is between 0 and 4, the total is rounded down and if it is between 5 and 9, it is rounded up.

In case of hybrid electric vehicles, the final result is the highest of the test results for conditions A and B as described in paragraph 6.2.1.1 of this Regulation.

3.2. Measurement of the sound emitted by stationary vehicles (for testing of vehicles in use)

3.2.1. Sound pressure level close to the outlet(s) of the exhaust system

In addition, so as to facilitate the subsequent testing of vehicles in use, the sound pressure level shall be measured near the outlet of the exhaust system (silencing system), in conformity with the requirements set out below, and the result of the measurement shall be included in the test report prepared for the issuance of the document referred to in Annex 1 to this Regulation.

3.2.2. Measuring instruments

The measurements shall be made using a precision sound level meter in accordance with paragraph 1 of this annex.

3.2.3. Conditions for measurements

3.2.3.1. Condition of the vehicle

Before the measurements are started, the vehicle engine shall be brought to its normal operating temperature. If the vehicle is equipped with automatic fans, no adjustment shall be made to them during the measurement of the sound level.

While measurements are being made, the gear lever shall be in neutral. If the transmission cannot be disconnected, the drive wheel of the vehicle should be allowed to run under no-load conditions by, for example, placing the vehicle on a support or on rollers.

3.2.3.2. Test site

Any area not subject to major acoustic perturbations may be used as a test site. Level areas covered with concrete, asphalt or some other hard material and are highly reflective are suitable; surfaces consisting of earth which has been tamped down shall not be used. The test site shall have at least the dimensions of a rectangle the sides of which shall be 3 m from the outline of the vehicle (excluding handlebars). No significant obstacle such as a person other than the observer and the driver shall be within this rectangle.

The vehicle shall be placed within the above-mentioned rectangle in such a way that the measuring microphone is at least 1 metre from any stone edging.

3.2.3.3. Miscellaneous

Instrument readings caused by ambient or wind noise shall be at least 10 dB(A) less than the sound level to be measured. The microphone may be fitted with a suitable wind-guard provided that its effect on microphone sensitivity is taken into account.

3.2.4. Method of measurement

3.2.4.1. Number of measurements

At least three measurements shall be made at each measurement point. The measurements shall be considered valid only if the difference between the results of three consecutive measurements is not more than 2 dB(A).

3.2.4.2. Positioning of the microphone (see Figure 2)

The microphone shall be located at a distance of 0,5 ± 0,01 m from the reference point of the exhaust pipe defined in Figure 3 and at an angle of 45 ± 5° to the vertical plane containing the flow axis of the pipe termination. The microphone shall be at the height of the reference point, but not less than 0,2 m from the ground surface. The reference axis of the microphone shall lie in a plane parallel to the ground surface and shall be directed towards the reference point on the exhaust outlet.

Figure 2

Microphone positions for the measurement of sound of the stationary vehicle

Height of the reference point on exhaust outlet

Figure 3

Reference point

Key: T = top view S = side view 1 = reference point 2 = road surface A = mitered pipe B = bent down pipe C = straight pipe D = vertical pipe

The reference point shall be the highest point satisfying the following conditions:

(a) The reference point shall be at the end of the exhaust pipe,

(b) The reference point shall be on the vertical plane containing the exhaust outlet centre and the flow axis of the exhaust pipe termination.

If two microphone positions are possible, the location farthest laterally from the vehicle longitudinal centreline shall be used.

If the flow axis of the exhaust outlet pipe is at 90° ± 5° to the vehicle longitudinal centreline, the microphone shall be located at the point that is the furthest from the engine.

If a vehicle has two or more exhaust outlets spaced less than 0,3 m apart and connected to a single silencer, only one measurement shall be made. The microphone shall be located relative to the outlet the farthest from the vehicle's longitudinal centreline, or, when such outlet does not exist, to the outlet that is highest above the ground.

For vehicles having an exhaust provided with outlets spaced more than 0,3 m apart, one measurement is made for each outlet as if it were the only one, and the highest sound pressure level shall be noted.

For the purpose of roadside checking, the reference point may be moved to the outer surface of the vehicle body.

For vehicles equipped with multiple exhaust outlets, the reported sound pressure level shall be for the outlet having the highest average sound pressure level.

3.2.4.3. Operating conditions

The engine speed shall be held steady at one of the following values:

50 per cent of nrated if nrated exceeds 5 000 min– 1

75 per cent of nrated if nrated does not exceed 5 000 min– 1

Where nrated is the rated engine speed as defined in paragraph 2.4 of this Regulation.

For a vehicle which cannot reach, in a stationary test, the target engine speed defined above, 95 per cent of the maximum engine speed reachable in a stationary test shall be used instead as target engine speed.

The engine speed shall be gradually increased from idle to the target engine speed and held constant within a tolerance band of ± 5 per cent. Then the throttle control shall be rapidly released and the engine speed shall be returned to idle. The sound pressure level shall be measured during a period consisting of constant engine speed of at least 1 s and throughout the entire deceleration period. The maximum sound level meter reading shall be taken as the test value.

A measurement shall be regarded as valid only if the test engine speed did not deviate from the target engine speed by more than the specified tolerance of ± 5 per cent for at least 1 s.

3.2.4.4. Measurements shall be made at the microphone location(s) prescribed above. The maximum A-weighted sound pressure level indicated during the test shall be noted, retaining one significant figure behind the decimal place (e.g. 92,45 shall be noted as to 92,5 while 92,44 shall be noted as to 92,4).

The test shall be repeated until three consecutive measurements that are within 2,0 dB(A) of each other are obtained at each outlet.

The test result for a given outlet is the arithmetic average of the three valid measurements, mathematically rounded to the nearest integer value (e.g. 92,5 shall be noted as to 93 while 92,4 shall be noted as to 92).

3.2.4.5. Multi-mode exhaust system

3.2.4.5.1. Vehicles equipped with a multiple mode, manually adjustable exhaust system shall be tested in all modes.

3.2.4.5.2. For vehicles equipped with a multi-mode exhaust system and a manual exhaust mode control the reported sound pressure level shall be for the mode having the highest average sound pressure level.

4. SOUND FROM THE VEHICLE IN MOTION (DATA REPORTED TO FACILITATE TESTING OF THE VEHICLE IN USE).

4.1. A test procedure for in use compliance tests may be defined by a Contracting Party, taking due account of any differences from the test conditions used at type-approval.

4.2. In order to facilitate in use compliance test of vehicles, the following information relating to the sound-pressure level measurements carried out in accordance with paragraph 1 of Annex 3 for the vehicle in motion is referred to as in use compliance reference data:

(a) Gear (i) or, for vehicles tested with non-locked gear ratios, the position of the gear selector chosen for the test;

(b) The vehicle speed vAA′ in km/h at the beginning of the full throttle acceleration test in gear (i); and

(c) The final test result in dB(A) as determined according to paragraph 3.1.4 of this annex.

4.3. The in use compliance reference data shall be entered in the communication form conforming to Annex 1.

5. ORIGINAL EXHAUST (SILENCING) SYSTEM

5.1. Requirements for silencers containing absorbent fibrous materials

5.1.1. Fibrous absorbent material shall be asbestos-free and may be used in the construction of silencers only if suitable devices ensure that the fibrous absorbent material is kept in place for the whole time that the silencer is being used and the exhaust or silencing system meets the requirements of any one of paragraphs 5.1.2, 5.1.3, 5.1.4 or 5.1.5 below.

5.1.2. After removal of the fibrous material, the sound-level shall conform to the requirements of paragraph 6.2.1.3 of this Regulation.

5.1.3. The fibrous absorbent material may not be placed in those parts of the silencer through which the exhaust gases pass and shall conform to the following requirements:

5.1.3.1. The material shall be heated at a temperature of 650 ± 5 °C for four hours in a furnace without reduction in the average length, diameter or bulk density of the fibre;

5.1.3.2. After heating at 650 ± 5 °C for one hour in a furnace, at least 98 per cent of the material shall be retained in a sieve of nominal aperture size 250 μm conforming to ISO standard 3310/1:2000 when tested in accordance with ISO standard 2559:2011.

5.1.3.3. The loss in weight of the material shall not exceed 10,5 per cent after soaking for 24 h at 90 ± 5 °C in a synthetic condensate of the following composition: 1 N hydrobromic acid (HBr) 10 ml 1 N sulphuric acid (H2SO4) 10 ml Distilled water to make up to 1 000 ml Note: The material must be washed in distilled water and dried for one hour at 105 °C before weighing.

5.1.4. Before the system is tested in accordance with paragraph 3 above, it shall be put into a normal state for road use by one of the following methods:

5.1.4.1. Conditioning by continuous road operation

5.1.4.1.1. Depending on the engine capacity of the vehicle, the minimum distances to be completed during conditioning shall be:

Category of vehicle according to cylinder capacity in cm3 Distance (km) 1. ≤ 250 4 000 2. > 250 ≤ 500 6 000 3. > 500 8 000

5.1.4.1.2. 50 per cent ± 10 per cent of this conditioning cycle shall consist of town driving and the remainder of long-distance runs at high vehicle speed; the continuous road cycle may be replaced by a corresponding test-track programme;

5.1.4.1.3. The two vehicle speed regimes shall be alternated at least six times;

5.1.4.1.4. The complete test programme shall include a minimum of 10 breaks of at least 3 h duration in order to reproduce the effects of cooling and condensation.

5.1.4.2. Conditioning by pulsation

5.1.4.2.1. The exhaust system or components thereof shall be fitted to the vehicle or to the engine.

In the former case, the vehicle shall be mounted on a roller dynamometer. In the second case, the engine shall be mounted on a test bench.

The test apparatus, a detailed diagram of which is shown in Figure 4, shall be fitted at the outlet of the exhaust system. Any other apparatus providing equivalent results shall be acceptable.

Figure 4

Test apparatus for conditioning by pulsation

optional optional

1. Inlet flange or sleeve for connection to the rear of the test exhaust system 2. Hand-operated regulating valve. 3. Compensating reservoir with a maximum capacity of 40 1 and a filling time of not less than one second. 4. Pressure switch with an operating range of 5 to 250 kPa. 5. Time delay switch. 6. Pulse counter. 7. Quick-acting valve, such as exhaust brake valve 60 mm in diameter, operated by a pneumatic cylinder with an output of 120 N at 400 kPa. The response time, both when opening and closing, shall not exceed 0,5 seconds. 8. Exhaust gas evacuation. 9. Flexible pipe. 10. Pressure gauge.

5.1.4.2.2. The test equipment shall be adjusted so that the flow of exhaust gases is alternately interrupted and restored 2 500 times by a rapid-action valve.

5.1.4.2.3. The valve shall open when the exhaust gas back-pressure, measured at least 100 mm downstream of the intake flange, reaches a value of between 35 and 40 kPa. Should such a figure be unattainable because of the engine characteristics, the valve shall open when the gas back-pressure reaches a level equivalent to 90 per cent of the maximum that can be measured before the engine stops. It shall close when this pressure does not differ by more than 10 per cent from its stabilised value with the valve open.

5.1.4.2.4. The time-delay switch shall be set for the duration of exhaust gases calculated on the basis of the requirements of paragraph 5.1.4.2.3 above.

5.1.4.2.5. The engine speed shall be 75 per cent of the rated engine speed as defined in paragraph 2.4 of this Regulation.

5.1.4.2.6. The power indicated by the dynamometer shall be 50 per cent of the full-throttle power measured at 75 per cent of the rated engine speed as defined in paragraph 2.4 of this Regulation.

5.1.4.2.7. Any drainage holes shall be closed off during the test.

5.1.4.2.8. The entire test shall be completed within 48 hours. If necessary, a cooling period shall be allowed after each hour.

5.1.4.3. Conditioning on a test bench

5.1.4.3.1. The exhaust system shall be fitted to an engine representative of the type fitted to the vehicle for which the system is designed, and mounted on a test bench.

5.1.4.3.2. Conditioning shall consist of the specified number of test bench cycles for the engine capacity class of vehicle, for which the exhaust system was designed. The number of cycles for each vehicle class shall be:

Category of vehicle according to cylinder capacity in cm3 Number of cycles 1. ≤ 250 6 2. > 250 ≤ 500 9 3. > 500 12

5.1.4.3.3. Each test-bench cycle shall be followed by a break of at least six hours in order to reproduce the effects of cooling and condensation.

5.1.4.3.4. Each test-bench cycle shall consist of six phases. The engine conditions for, and the duration of, each phase shall be:

Phase Conditions Duration of phase Engines of less than 250 cm3 Engines of 250 cm3 or more (min) (min) 1 Idling 6 6 2 25 per cent load at 75 per cent of nrated 40 50 3 50 per cent load at 75 per cent of nrated 40 50 4 100 per cent load at 75 per cent of nrated 30 10 5 50 per cent load at 100 per cent of nrated 12 12 6 25 per cent load at 100 per cent of nrated 22 22 Total time 2 h 30 min 2 h 30 min

5.1.4.3.5. During this conditioning procedure, at the request of the manufacturer, the engine and the silencer may be cooled in order that the temperature recorded at a point not more than 100 mm from the exhaust gas outlet does not exceed that measured when the vehicle is running at 110 km/h or 75 per cent of the rated engine speed as defined in paragraph 2.4 of this Regulation in top gear. The engine and/or vehicle speeds shall be determined with a tolerance of ± 3 per cent.

5.1.5. Exhaust gases are not in contact with fibrous materials and fibrous materials are not under the influence of pressure variations.

5.2. Diagram and markings

5.2.1. The diagram and a dimensioned cross-section of the silencer shall be annexed to the document mentioned in Annex 1 to this Regulation.

5.2.2. All original silencers shall bear at least the following:

(a) The ‘E’ mark followed by the reference to the country which granted the type-approval;

(b) The vehicle manufacturer's name or trademark; and

(c) The make and identifying part number.

This reference shall be legible, indelible and visible in the position at which it is to be fitted.

5.2.3. Any packaging of original replacements for exhaust or silencing systems shall be marked legibly with the words ‘original part’ and the make and type reference integrated together with the ‘E’ mark and also the reference of the country of origin.

5.3. Intake silencers

If the engine intake has to be fitted with an air filter and/or intake silencer in order to comply with the permissible sound level, the filter and/or silencer shall be regarded as part of the silencer and the requirements of paragraphs 5.1 and 5.2 above shall also be applicable to them.

(1) Independent measurements of speed are when two or more separate devices will determine the values of vAA′ and vBB′. A continuous measuring device such as radar will determine all required speed information with one device.