environment.sources.cnossos_rail

CNOSSOS-EU railway source emission (Directive 2002/49/EC Annex II, 2.3).

The common noise assessment methods of the European Union describe a railway track as two incoherent source lines at the centre of the track, at $h=0.5$ m (source A) and $h=4.0$ m (source B) above the plane tangent to the two upper rail surfaces. Every physical source of a vehicle is allocated to one of the two heights and contributes a directional sound power per metre of line

$$L_{W,eq,line,i}^{\prime }(\psi ,\varphi )=L_{W,0,dir,i}(\psi ,\varphi )+10{\log }_{10}\left(\frac{Q}{1000v}\right)\text{\hspace{1em}(2.3.2)}$$

for a running train, or $+10{\log }_{10}(T_{idle}/(T_{ref}L))$ (2.3.4) for an idling one. This module implements the whole of 2.3 together with the coefficient database of Appendix G, in the twenty-four 1/3-octave bands from 50 Hz to 10 kHz, and energy-sums them into the eight octave bands the propagation stage consumes.

Which text is implemented

Annex II was replaced by Commission Directive (EU) 2015/996, corrected by the corrigendum of OJ L 5, 10.1.2018 and amended by Commission Delegated Directive (EU) 2021/1226. The consolidated text (02002L0049) is what is implemented here, and every shipped table records the instrument it comes from:

• the roughness-to-frequency conversion uses $f=v/\lambda$ with v in m/s as corrected in 2018 (the 2015 text says km/h, which is wrong by a factor 3.6);
• the whole of Appendix G is the corrigendum’s replacement text, with Tables G-1b, G-2, G-3a, G-4 and G-7 as replaced by (EU) 2021/1226 and Tables G-1a, G-3b, G-3c, G-5 and G-6 as re-issued in 2018 with the band labels corrected in 2021. The letter suffixes are this module’s shorthand: the Official Journal prints two tables under the number G-1 (wheel then rail roughness) and three sections under G-3, and names neither set;
• curve squeal follows the 2021 rule (5 dB / 8 dB by radius, with a separate tram rule and a turnout rule), not the 2015 one;
• bridge noise is a separate source built on the transfer function L_H,bridge,i of Table G-7 (2.3.18 as replaced in 2021), not the constant C_bridge of 2015;
• the vertical directivity of source A is the 2021 form, with no absolute-value bars and identically zero for $\psi \le 0$. The superseded 2015 form is available through DirectivityEdition for comparison with pre-2021 studies, because the two differ over the whole lower half space.

What is verified against digits and what is not

Annex II prints no worked example for the railway source. The end-to-end chain implemented here is pinned against the emission test workbook published with the Commission’s CNOSSOS-EU source module, which was computed with the 2015 coefficient database; the shipped tables are therefore verified as transcriptions, and the equations that combine them are verified end to end against an independent implementation. Two points are interpretation, not transcription, and are documented as such: RoughnessInterpolation (the Directive describes the wavelength-to- frequency resampling in prose only) and the horizontal directivity of traction noise (2.3.15 enumerates rolling, impact, squeal, braking, fans and aerodynamic effects; the reference module applies the dipole to every source, which is what is done here).

Scope

This is the emission stage only. Splitting a source line into equivalent point sources is explicitly outside the scope of the method (2.5.3), and the CNOSSOS propagation model is not ISO 9613-2, so the hand-off to outdoor_propagation mixes two methods and is a convenience, not a normative chain.

Auto-generated from the source docstrings by scripts/generate_api_docs.py (make api-docs). Do not edit by hand.

AERODYNAMIC_REFERENCE_SPEED

Constant (float).

AERODYNAMIC_REFERENCE_SPEED = 300.0

aerodynamic_sound_power

aerodynamic_sound_power(
    speed: float = 300.0,
    *,
    reference: tuple[NDArray[np.float64], NDArray[np.float64]] | None = None,
    alpha: float = 50.0,
) -> tuple[NDArray[np.float64], NDArray[np.float64]]

Aerodynamic sound power of (2.3.13) and (2.3.14), in dB.

$L_{W,0,i}=L_{W,0,h,i}(v_0)+{\alpha }_{h,i}{\log }_{10}(v/v_0)$ with $v_0=300$ km/h. At the reference speed the result is Table G-6 verbatim.

Parameters

Name	Description
speed	Train speed v, in km/h.
reference	(source A, source B) reference spectra at v_0, or None (the default) for Table G-6.
alpha	Speed exponent alpha_h,i; Table G-6 gives 50 in every band.

Returns: (source A spectrum, source B spectrum), 24 values each.

Raises

Exception	When
ValueError	If the speed is not positive.

AERODYNAMIC_THRESHOLD_SPEED

Constant (float).

AERODYNAMIC_THRESHOLD_SPEED = 200.0

BrakeType

BrakeType(*values)

Digit 3 of the vehicle descriptor, Table [2.3.a].

bridge_transfer

bridge_transfer(bridge: BridgeType | str) -> NDArray[np.float64]

Bridge transfer function L_H,bridge,i of Table G-7, in dB per axle.

Parameters

Name	Description
bridge	A BridgeType member or its column label.

Returns: The 24 1/3-octave values, in dB.

Raises

Exception	When
ValueError	If the column is not tabulated.

BridgeType

BridgeType(*values)

Columns of Table G-7, labelled by the A-weighted bridge excess.

contact_filter

contact_filter(
    filter_: ContactFilter | tuple[float, float],
) -> tuple[NDArray[np.float64], NDArray[np.float64]]

Contact filter A_3 of Table G-2.

Parameters

Name	Description
filter_	A ContactFilter member or the (wheel load in kN, wheel diameter in mm) pair that labels the column.

Returns: (wavelengths in mm, levels in dB).

Raises

Exception	When
ValueError	If the combination is not tabulated.

ContactFilter

ContactFilter(*values)

Columns of Table G-2, as (wheel load in kN, wheel diameter in mm).

curve_squeal_excess

curve_squeal_excess(
    radius: float,
    *,
    tram: bool = False,
    turnout: bool = False,
    track_length: float = 50.0,
) -> float

Curve-squeal excess added to the rolling noise, in dB.

The rule is the one (EU) 2021/1226 Annex point (4)(b) substituted for the 2015 text: for trains, 8 dB at $R\le 300$ m and 5 dB at $300<R\le 500$ m over at least 50 m of curve, and 8 dB on switch turnouts with $R\le 300$ m whatever their length; for trams, 5 dB on curves and switch turnouts with $R\le 200$ m. The excess applies at all frequencies.

Parameters

Name	Description
radius	Curve radius R, in m.
tram	True for a tram, which follows its own rule.
turnout	True for a switch turnout, where the minimum curve length does not apply.
track_length	Length of track along the curve l_track, in m.

Returns: The excess, in dB (0.0 where no squeal is modelled).

Raises

Exception	When
ValueError	If the radius or the track length is not positive.

DirectivityEdition

DirectivityEdition(*values)

Which text of the vertical directivity (2.3.16) to evaluate.

horizontal_directivity

horizontal_directivity(
    phi: float,
    *,
    frequencies: Any = (50.0, 63.0, 80.0, 100.0, 125.0, 160.0, 200.0, 250.0, 315.0, 400.0, 500.0, 630.0, 800.0, 1000.0, 1250.0, 1600.0, 2000.0, 2500.0, 3150.0, 4000.0, 5000.0, 6300.0, 8000.0, 10000.0),
) -> NDArray[np.float64]

Horizontal directivity dL_W,dir,hor,i of (2.3.15), in dB.

$10{\log }_{10}(0.01+0.99{\sin }^2\varphi )$: a dipole, identical in every band, equal to 0 dB broadside ($\varphi =90^{\circ }$) and to $10{\log }_{10}0.01=-20$ dB along the track. The Directive offers it “by default” for rolling, impact, squeal, braking, fans and aerodynamic effects; since no other horizontal directivity is given and traction noise includes the fans, it is applied here to every source, as the Commission’s reference module does.

Parameters

Name	Description
phi	Horizontal angle phi, in degrees, measured from the direction of travel (Figure [2.3.b]).
frequencies	Midband frequencies, used only for the array shape.

Returns: The correction, in dB, one value per band.

Raises

Exception	When
ValueError	If the angle is not finite.

impact_roughness

impact_roughness(single: Any, joint_density: float) -> NDArray[np.float64]

Impact roughness L_R,IMPACT,i of (2.3.12), in dB.

$L_{R,IMPACT,i}=L_{R,\text{IMPACT-SINGLE},i}+10{\log }_{10}(n_l/0.01)$, so at the tabulated density of one joint per 100 m the table is returned verbatim.

Parameters

Name	Description
single	Single-impact roughness on the frequency grid, in dB.
joint_density	Joint density n_l, in m^-1.

Returns: L_R,IMPACT,i, in dB.

Raises

Exception	When
ValueError	If the joint density is negative or not finite.

impact_roughness_single

impact_roughness_single() -> tuple[NDArray[np.float64], NDArray[np.float64]]

Impact roughness L_R,IMPACT-SINGLE of Table G-4.

The table is given for a joint density $n_l=0.01$ m^-1, that is one switch, joint or crossing per 100 m, which is also the default the Directive prescribes for jointed track.

Returns: (wavelengths in mm, levels in dB).

octave_bands_from_third_octaves

octave_bands_from_third_octaves(levels: Any) -> NDArray[np.float64]

Energy-sum a 24-band 1/3-octave spectrum into the eight octave bands.

Annex II 2.3.2 requires the directional sound power to be derived in 1/3 octave bands and then “expressed in octave bands by energetically adding each pertaining 1/3 octave band together into the corresponding octave band”.

Parameters

Name	Description
levels	The 24 1/3-octave levels from 50 Hz to 10 kHz, in dB.

Returns: The eight octave levels from 63 Hz to 8 kHz, in dB.

Raises

Exception	When
ValueError	If the spectrum is not 24 bands.

rail_roughness

rail_roughness(
    roughness: RailRoughnessClass | str,
) -> tuple[NDArray[np.float64], NDArray[np.float64]]

Rail roughness L_r,TR of Table G-1b.

Only the two maintained classes E and M are tabulated; the N and B classes of Table [2.3.b] carry no spectrum in Appendix G and have to be supplied by the Member State.

Parameters

Name	Description
roughness	The RailRoughnessClass of digit 2 of the track descriptor.

Returns: (wavelengths in mm, levels in dB).

Raises

Exception	When
ValueError	If the class carries no spectrum in Table G-1b.

RailPad

RailPad(*values)

Digit 3 of the track descriptor: rail-pad dynamic stiffness.

(EU) 2021/1226 Annex point (3) replaced “acoustic” stiffness by dynamic stiffness and re-worded the hard class as “Hard (800-1 000 MN/m)”.

RailRoughnessClass

RailRoughnessClass(*values)

Digit 2 of the track descriptor, Table [2.3.b].

RAILWAY_MINIMUM_SPEED

Constant (float).

RAILWAY_MINIMUM_SPEED = 50.0

RAILWAY_OCTAVE_BANDS

Constant (tuple).

RAILWAY_OCTAVE_BANDS = (63.0, 125.0, 250.0, 500.0, 1000.0, 2000.0, 4000.0, 8000.0)

RAILWAY_SOURCE_HEIGHTS

Constant (tuple).

RAILWAY_SOURCE_HEIGHTS = (0.5, 4.0)

railway_source_power

railway_source_power(
    traffic: RailwayVehicle | list[RailwayVehicle] | tuple[RailwayVehicle, ...],
    track: RailwayTrack,
    *,
    psi: float = 0.0,
    phi: float = 90.0,
    reference_time: float = 12.0,
    minimum_speed: float | None = None,
    interpolation: RoughnessInterpolation = ...,
    directivity_edition: DirectivityEdition = ...,
) -> RailwayEmissionResult

Directional sound power per metre of a railway source line (2.3.1).

Assembles, for every vehicle of the traffic and both source heights, the rolling noise (2.3.8)-(2.3.11), the impact noise (2.3.12), the curve squeal, the traction noise, the aerodynamic noise (2.3.13)-(2.3.14) and the bridge noise (2.3.18); applies the directivity of (2.3.15)-(2.3.17); adds the flow term of (2.3.2) or (2.3.4); and energy-sums everything over the traffic.

Rolling, impact, squeal and bridge noise sit at source A. Traction and aerodynamic noise are tabulated separately for the two heights, so their split between A and B is read from the data rather than assumed. Rolling noise is excluded while a vehicle idles, and impact noise is not modelled below the minimum speed nor while idling.

Parameters

Name	Description
traffic	One RailwayVehicle or a sequence of them.
track	The RailwayTrack of the section.
psi	Vertical angle psi to the receiver, in degrees.
phi	Horizontal angle phi to the receiver, in degrees; the default 90 deg is broadside, where the dipole correction is 0 dB.
reference_time	Reference period T_ref of (2.3.4), in the same unit as idling_time.
minimum_speed	Speed floor used to determine the total effective roughness, in km/h; None (the default) selects 50 km/h, or 30 km/h for a tram. Pass 0 to switch the floor off, which also switches off the exclusion of impact noise below it.
interpolation	The RoughnessInterpolation rule.
directivity_edition	Which text of (2.3.16) to evaluate.

Returns: A RailwayEmissionResult.

Raises

Exception	When
ValueError	If the traffic is empty or an input is invalid.

RAILWAY_THIRD_OCTAVE_BANDS

Constant (tuple).

RAILWAY_THIRD_OCTAVE_BANDS = (50.0, 63.0, 80.0, 100.0, 125.0, 160.0, 200.0, 250.0, 315.0, 400.0, 500.0, 630.0, 800.0, 1000.0, 1250.0, 1600.0, 2000.0, 2500.0, 3150.0, 4000.0, 5000.0, 6300.0, 8000.0, 10000.0)

RailwayEmissionResult

RailwayEmissionResult(
    third_octave_frequencies: NDArray[np.float64],
    frequencies: NDArray[np.float64],
    heights: tuple[float, float],
    third_octave_line_power: NDArray[np.float64],
    line_power: NDArray[np.float64],
    total_line_power: NDArray[np.float64],
    components: dict[str, tuple[NDArray[np.float64], NDArray[np.float64]]] = ...,
)

Directional sound power per metre of a CNOSSOS-EU railway source.

Attributes

Name	Description
third_octave_frequencies	The 24 1/3-octave midband frequencies, Hz.
frequencies	The eight octave midband frequencies, Hz.
heights	Heights of the two equivalent source lines, in m.
third_octave_line_power	L'_W,eq,line,i(psi,phi) per source height and 1/3-octave band, in dB re 1 pW per metre.
line_power	The same, energy-summed into octave bands.
total_line_power	The two heights summed, per octave band.
components	The 1/3-octave sound power of each physical source before the flow term and the directivity, keyed by "rolling", "traction", "aerodynamic" and "bridge", each holding the (source A, source B) pair.

RailwayEmissionResult.plot()

RailwayEmissionResult.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes

Plot the per-metre line power of the two equivalent source heights.

RailwayTrack

RailwayTrack(
    rail_roughness: tuple[Any, Any],
    track_transfer: Any,
    impact_roughness: tuple[Any, Any] | None = None,
    joint_density: float = 0.01,
    bridge_transfer: Any | None = None,
    squeal_excess: float = 0.0,
    length: float = 100.0,
)

The Appendix G data of one track section.

Attributes

Name	Description
rail_roughness	(wavelengths in mm, levels in dB) of Table G-1b.
track_transfer	L_H,TR,i of Table G-3a, 24 values in dB.
impact_roughness	(wavelengths in mm, levels in dB) of Table G-4, or None where there is no joint, switch or crossing.
joint_density	Joint density n_l, in m^-1.
bridge_transfer	L_H,bridge,i of Table G-7 where the section is on a bridge, or None.
squeal_excess	Curve-squeal excess in dB, from curve_squeal_excess.
length	Length L of the track section, in m; used only by the idling flow term (2.3.4).

RailwayVehicle

RailwayVehicle(
    stock: RollingStock,
    flow_rate: float = 0.0,
    speed: float = 0.0,
    condition: RunningCondition = ...,
    idling_time: float = 0.0,
)

One vehicle of the traffic on a track section.

Attributes

Name	Description
stock	The RollingStock data of the vehicle type.
flow_rate	Average number of vehicles per hour Q.
speed	Their speed v on the track section, in km/h.
condition	The RunningCondition c.
idling_time	Total idling time T_idle within T_ref, in the same unit as T_ref; used only when condition is idling.

REFERENCE_JOINT_DENSITY

Constant (float).

REFERENCE_JOINT_DENSITY = 0.01

rolling_sound_power

rolling_sound_power(
    roughness: Any,
    transfer: Any,
    axles: float,
) -> NDArray[np.float64]

One rolling-noise component of (2.3.8) to (2.3.10), in dB.

$L_{W,0,i}=L_{R,TOT,i}+L_{H,i}+10{\log }_{10}(N_a)$: the same addition serves the track, the wheel and the freight superstructure, each with its own transfer function. All three sit at source A.

Parameters

Name	Description
roughness	Total effective roughness L_R,TOT,i, in dB.
transfer	Transfer function L_H,i, in dB per axle.
axles	Number of axles per vehicle N_a.

Returns: The component sound power, in dB.

Raises

Exception	When
ValueError	If axles is not a positive number.

RollingStock

RollingStock(
    axles: int,
    wheel_roughness: tuple[Any, Any],
    contact_filter: tuple[Any, Any],
    wheel_transfer: Any,
    superstructure_transfer: Any | None = None,
    traction: tuple[Any, Any] | None = None,
    aerodynamic: tuple[Any, Any] | None = None,
    aerodynamic_alpha: float = 50.0,
    tram: bool = False,
)

The Appendix G data of one vehicle type, on its own wavelength grids.

Every field is the spectrum the method needs, so a Member State substitutes its own database simply by building this object from its own tables rather than from the cnossos_rail look-ups.

Attributes

Name	Description
axles	Number of axles per vehicle N_a.
wheel_roughness	(wavelengths in mm, levels in dB) of Table G-1a.
contact_filter	(wavelengths in mm, levels in dB) of Table G-2.
wheel_transfer	L_H,VEH,i of Table G-3b, 24 values in dB.
superstructure_transfer	L_H,VEH,SUP,i of Table G-3c for a freight wagon, or None for any other vehicle type.
traction	(source A, source B) spectra of Table G-5, or None for an unpowered vehicle.
aerodynamic	(source A, source B) reference spectra of Table G-6 at v_0, or None to leave aerodynamic noise out.
aerodynamic_alpha	Speed exponent of (2.3.13) and (2.3.14).
tram	True for a tram or light metro, which uses the lower minimum speed and the tram squeal rule.

roughness_to_frequency

roughness_to_frequency(
    levels: Any,
    wavelengths: Any,
    speed: float,
    *,
    frequencies: Any = (50.0, 63.0, 80.0, 100.0, 125.0, 160.0, 200.0, 250.0, 315.0, 400.0, 500.0, 630.0, 800.0, 1000.0, 1250.0, 1600.0, 2000.0, 2500.0, 3150.0, 4000.0, 5000.0, 6300.0, 8000.0, 10000.0),
    interpolation: RoughnessInterpolation = ...,
) -> NDArray[np.float64]

Resample a roughness spectrum from wavelength onto frequency.

A roughness level is tabulated against wavelength and has to be read at $\lambda =v/f$ with v in m/s (the corrigendum of OJ L 5, 10.1.2018; the 2015 text says km/h, which is wrong by a factor 3.6). The value at the wanted wavelength is obtained from the two neighbouring tabulated bands according to interpolation; beyond the ends of the table the end value is held.

Parameters

Name	Description
levels	Roughness levels of the table, in dB.
wavelengths	Wavelengths of the table, in mm, in any monotonic order.
speed	Train speed v, in km/h.
frequencies	Target midband frequencies, in Hz.
interpolation	The RoughnessInterpolation rule.

Returns: The spectrum on the target frequency grid, in dB.

Raises

Exception	When
ValueError	If an input is invalid.

RoughnessInterpolation

RoughnessInterpolation(*values)

How a roughness spectrum is resampled from wavelength onto frequency.

The Directive describes the resampling in prose only: “the two corresponding 1/3 octave bands defined in the wavelength domain shall be averaged energetically and proportionally”. No formula and no example is given, so the rule has to be chosen, and the choice is the single largest interpretation risk of the railway model.

RunningCondition

RunningCondition(*values)

Running condition c of 2.3.2.

Only two conditions are modelled: constant speed, which the Directive says is valid as well when the train accelerates or decelerates, and idling.

superstructure_transfer

superstructure_transfer() -> NDArray[np.float64]

Superstructure transfer L_H,VEH,SUP,i of Table G-3c, in dB per axle.

Only one superstructure is tabulated, the “EU standard” of vehicle type a (freight), and it is 0.0 dB in every band, so (2.3.10) reduces to $L_{R,TOT,i}+10{\log }_{10}(N_a)$. The contribution is considered for freight wagons only.

Returns: The 24 1/3-octave values, all zero.

total_effective_roughness

total_effective_roughness(
    rail: Any,
    wheel: Any,
    filter_: Any,
) -> NDArray[np.float64]

Total effective roughness L_R,TOT,i of (2.3.7), in dB.

$L_{R,TOT,i}=10{\log }_{10}(10^{L_{r,TR,i}/10}+10^{L_{r,VEH,i}/10})+A_{3,i}$. All three spectra must already be on the frequency grid, that is resampled with roughness_to_frequency at the speed of interest.

Parameters

Name	Description
rail	Rail roughness L_r,TR,i, in dB.
wheel	Wheel roughness L_r,VEH,i, in dB.
filter_	Contact filter A_3,i, in dB.

Returns: L_R,TOT,i, in dB.

Raises

Exception	When
ValueError	If the spectra are not 24 bands each.

track_transfer

track_transfer(track: TrackTransferClass | str) -> NDArray[np.float64]

Track transfer function L_H,TR,i of Table G-3a, in dB per axle.

Parameters

Name	Description
track	A TrackTransferClass member or its column code.

Returns: The 24 1/3-octave values, in dB.

Raises

Exception	When
ValueError	If the column is not tabulated.

TrackBase

TrackBase(*values)

Digit 1 of the track descriptor, Table [2.3.b].

TrackCurvature

TrackCurvature(*values)

Digit 6 of the track descriptor, Table [2.3.b].

TrackDescriptor

TrackDescriptor(
    base: TrackBase,
    roughness: RailRoughnessClass,
    pad: RailPad,
    measure: TrackMeasure = ...,
    joints: RailJoints = ...,
    curvature: TrackCurvature = ...,
)

The six-digit track descriptor of Table [2.3.b].

Attributes

Name	Description
base	Digit 1, the TrackBase.
roughness	Digit 2, the RailRoughnessClass.
pad	Digit 3, the RailPad dynamic stiffness.
measure	Digit 4, the TrackMeasure.
joints	Digit 5, the RailJoints.
curvature	Digit 6, the TrackCurvature.

TrackDescriptor.code

property

The descriptor written back out as a string.

TrackDescriptor.from_code()

classmethod

TrackDescriptor.from_code(code: str) -> TrackDescriptor

Parse a descriptor such as "BMSNNN".

Parameters

Name	Description
code	The six-character descriptor.

Returns: The parsed TrackDescriptor.

Raises

Exception	When
ValueError	If the code is not a valid six-digit descriptor.

TrackTransferClass

TrackTransferClass(*values)

Columns of Table G-3a, track base / rail pad of the track descriptor.

traction_sound_power

traction_sound_power(
    vehicle: TractionVehicle | str,
) -> tuple[NDArray[np.float64], NDArray[np.float64]]

Traction sound power per vehicle of Table G-5, in dB.

Because the Directive models only constant speed and idling and takes the source strength at maximum load, $L_{W,0,const,i}=L_{W,0,idling,i}$, so this one table serves both running conditions.

Parameters

Name	Description
vehicle	A TractionVehicle member or its description.

Returns: (source A spectrum, source B spectrum), 24 values each.

Raises

Exception	When
ValueError	If the vehicle is not tabulated.

TractionVehicle

TractionVehicle(*values)

Columns of Table G-5, the traction sound power per vehicle.

TRAM_MINIMUM_SPEED

Constant (float).

TRAM_MINIMUM_SPEED = 30.0

VehicleDescriptor

VehicleDescriptor(
    vehicle_type: VehicleType,
    axles: int,
    brake: BrakeType,
    measure: WheelMeasure = ...,
)

The four-digit vehicle descriptor of Table [2.3.a].

Attributes

Name	Description
vehicle_type	Digit 1, the VehicleType.
axles	Digit 2, the number of axles per vehicle.
brake	Digit 3, the BrakeType.
measure	Digit 4, the WheelMeasure.

VehicleDescriptor.code

property

The descriptor written back out as a string.

VehicleDescriptor.from_code()

classmethod

VehicleDescriptor.from_code(code: str) -> VehicleDescriptor

Parse a descriptor such as "a4cn" or "h16nn".

The second digit is the actual number of axles, so it may run to more than one character.

Parameters

Name	Description
code	The descriptor, first digit to last.

Returns: The parsed VehicleDescriptor.

Raises

Exception	When
ValueError	If the code is not a valid four-digit descriptor.

VehicleType

VehicleType(*values)

Digit 1 of the vehicle descriptor, Table [2.3.a].

vertical_directivity

vertical_directivity(
    psi: float,
    *,
    frequencies: Any = (50.0, 63.0, 80.0, 100.0, 125.0, 160.0, 200.0, 250.0, 315.0, 400.0, 500.0, 630.0, 800.0, 1000.0, 1250.0, 1600.0, 2000.0, 2500.0, 3150.0, 4000.0, 5000.0, 6300.0, 8000.0, 10000.0),
    height: int = 1,
    aerodynamic: bool = False,
    edition: DirectivityEdition = ...,
) -> NDArray[np.float64]

Vertical directivity dL_W,dir,ver,i of (2.3.16) and (2.3.17), in dB.

Source A (height = 1) follows (2.3.16), which (EU) 2021/1226 Annex point (4)(d) replaced: the absolute-value bars of the 2015 text are gone and the correction is identically zero for $\psi \le 0$. Source B (height = 2) follows (2.3.17) for the aerodynamic effect only, $10{\log }_{10}({\cos }^2\psi )$ for $\psi <0$, and is omni-directional for every other source.

Parameters

Name	Description
psi	Vertical angle psi, in degrees (Figure [2.3.b]).
frequencies	Midband frequencies f_c,i, in Hz.
height	1 for source A at 0.5 m, 2 for source B at 4.0 m.
aerodynamic	True to select the aerodynamic source at height = 2; ignored at height = 1.
edition	Which text of (2.3.16) to evaluate.

Returns: The correction, in dB, one value per band.

Raises

Exception	When
ValueError	If the angle is not finite or the height is not 1 or 2.

wheel_roughness

wheel_roughness(
    brake: BrakeType | str,
) -> tuple[NDArray[np.float64], NDArray[np.float64]]

Wheel roughness L_r,VEH of Table G-1a.

Parameters

Name	Description
brake	The BrakeType of digit 3 of the vehicle descriptor.

Returns: (wavelengths in mm, levels in dB).

Raises

Exception	When
ValueError	If the brake type is not tabulated.

wheel_transfer

wheel_transfer(diameter: WheelDiameter | float) -> NDArray[np.float64]

Wheel transfer function L_H,VEH,i of Table G-3b, in dB per axle.

Parameters

Name	Description
diameter	A WheelDiameter member or the diameter in mm.

Returns: The 24 1/3-octave values, in dB.

Raises

Exception	When
ValueError	If the diameter is not tabulated.

WheelDiameter

WheelDiameter(*values)

Columns of Table G-3b, the wheel diameter in mm, all “no measure”.

WheelMeasure

WheelMeasure(*values)

Digit 4 of the vehicle descriptor, Table [2.3.a].