CNOSSOS-EU (Road)
Note
The following information applies to both the European calculation methods (EU-2015, EU-2021) and the country-specific implementations (e.g. CNS-DE-2018, CNS-DE-2021, RVS-2019, RVS-2021), see also Calculation acc. to ... in chapter CNOSSOS-EU. If any differences in country-specific implementations exist, this is explicitly mentioned.
Emission Parameter
Assuming a steady traffic flow of Qm vehicles of category m per hour is assumed, with an average speed vm (in km/h), the sound power per metre in frequency band i of the source line LW', eq,line,i,m is defined by:
\(L_{W',eq,line,i,m}=L_{W,i,m}+10\lg(\frac{Q_m}{1000*v_m})\)
with
- LW,i,m is the directional sound power of a single vehicle (re. 10-12 W/m)
Vehicle Categories
Traffic flow Qm is expressed as yearly average per hour, per time period (Day, Evening, Night), for the following vehicle categories:
| Category m | Name | Description |
| 1 | Light motor vehicles | Passenger cars, delivery vans <= 3.5 tons, SUVs, MPVs including trailers and caravans |
| 2 | Medium heavy vehicles | Medium heavy vehicles, delivery vans > 3.5 tons, buses, motorhomes, etc. with two axles and twin tyre mounting on rear axle |
| 3 | Heavy vehicles | Heavy duty vehicles, touring cars, buses, with three or more axles |
| 4a | Powered two-wheelers | Two-, Three- and Four-wheel Mopeds |
| 4b | Motorcycles with and without sidecars, Tricycles and Quadricycles | |
| 5 | Open Category | for example used for electric vehicles at CNOSSOS-NO |
The following traffic amount formula and attributes apply to the respective input boxes on the Road dialog (see also Exact Counts):
| Input Box | in | Amount formula from categories m | CadnaA Attributes |
|---|---|---|---|
| Number of Vehicles/Hour | count | 1+2+3+4+5 | MT/E/N |
| Percentage heavy vehicles 2+3 | % | (2+3)/(1+2+3+4+5)*100% | PT/E/N |
| Heavy Trucks 3 in 2+3 | % | 3/(2+3)*100% | PLT/E/N |
| Powered two-wheelers 4a+4b | % | (4a+4b)/(1+2+3+4+5)*100% | PMCT,/E/N |
| Motorcycles 4b in 4a+4b | % | 4b/(4a+4b)*100% | PLLAT/E/N |
| Open Category 5 | % | 5/(1+2+3+4+5)*100% | P5T/E/N |
Source Types
The calculation of emission considers two main noise source types:
- rolling noise due to the tire-road interaction (while aerodynamic noise is incorporated in the rolling noise source).
- propulsion noise produced by the drive line (engine, exhaust, etc.) of the vehicle.
For light, medium and heavy motor vehicles (categories 1, 2 and 3), the total sound power corresponds to the energetic sum of the rolling and the propulsion noise. For two-wheelers (category 4), only propulsion noise is considered. Category 5 (only defined at CNOSSOS-NO) is treated the same as category 1-3.
Rolling Noise
The emission by rolling noise is described by the sound power level in the frequency band i per vehicle of class m=1, 2 or 3:
\(L_{WR,i,m}=A_{R,i,m}+B_{R,i,m}*\lg(\frac{v_m}{v_{ref}})+\Delta L_{WR,i,m}\)
with \(\Delta L_{WR,i,m}=\Delta L_{WR,road,i,m}+\Delta L_{sudded tyres,i,m}+\Delta L_{WR,acc,i,m}+\Delta L_{W,temp,i,m}\)
The coefficients AR,i,m and BR,i,m are given in octave bands for each vehicle category and for a reference speed vref = 70 km/h.
ΔLWR,i,m is the sum of the following corrections for rolling noise:
| Correction | accounts for the effect on rolling noise ... | Remarks |
| ΔLWR,road,i,m | by road surfaces different from the virtual reference surface | for details see below in this chapter |
| ΔLstudded tyres,i,m | by studded tyres with light vehicles (category 1) | enter period and percentage on the „Road“ tab, see CNOSSOS-EU |
| ΔLWR,acc,i,m | by crossings with traffic lights or roundabouts | for details see Crossing |
| ΔLW,temp | by the temperature T different from Tref = 20°C | see CNOSSOS-EU |
Propulsion Noise
The propulsion noise emission includes all contributions from engine, exhaust, gears, air intake, etc. The propulsion noise sound power level in the frequency band i for a vehicle of class m is:
\(L_{WP,i,m}=A_{P,i,m}+B_{P,i,m}*(\frac{v_m-v_{ref}}{v_{ref}})+\Delta L_{WP,i,m}\)
with \(\Delta L_{WP,i,m}=\Delta L_{WP,road,i,m}+\Delta L_{WP,grad,i,m}+\Delta L_{WP,acc,i,m}\)
The coefficients AP,i,m and BP,i,m are given in octave bands for each vehicle category and for a reference speed vref = 70 km/h.
ΔLWP,i,m is the sum of the following corrections for propulsion noise:
| Correction | accounts for the effect on propulsion noise ... | Remarks |
| ΔLWP,road,i,m | by different road surfaces due to sound absorption | for details see below in this chapter |
| ΔLWP,grad,i,m | by road gradients | for details see below in this chapter |
| ΔLWP,acc,i,m | by accelerating and decelerating vehicles at intersections | for details see Crossing |
Specification of Emission
Counts, MDTD
The specification of traffic counts using MDTD („Mean Daily Traffic Density“, vehicles/24h) in conjunction with a road type is only defined for the Austrian interpretations. Depending on the selection at „Calculation according to“ (see chapter CNOSSOS-EU) the distributions of following literature is used:
- 2015/996 AT: Distribution acc. to RVS-2019
- 2021/1226 AT: Distribution acc. to RVS-2021
- Other: Distribution acc. to RVS-2019
Exact Counts
This option enables to enter counts and percentages for the five CNOSSOS-specific vehicle classes.
Note that the „Number of Vehicles/hour“ addresses the total amount for all classes and the „Percentage heavy vehicles 2+3 (%)“ and the „Percentage Motorcycles 4a+4b (%)“ refer to that amount, whilst „Percentage Trucks 3 in 2+3 (%)“ and „Percentage Motorcycles 4b in 4a+4b (%)“ refer to the both above percentages being assumed as 100%.
Example:
-
Percentage Trucks 3 in 2+3 = 50%, for Day: 50% of 15% gives 7.5%,
-
resulting in 7.5% vehicles in each of classes 2 and 3
-
Percentage Motorcycles 4a+4b =0%: no motorcycles in 4a and 4b
The emission data for vehicle categories can be edited via the library „Vehicle Classes“ (see Vehicle Classes) and selected via the configuration of calculations (see CNOSSOS-EU, Vehicle Classes).
LwA‘ dB(A)
direct input of L‘wA in dB(A)
Diurnal Pattern
see Common Input Data, Diurnal Pattern
Source Geometry
A road with multiple lanes can be considered in the calculation:
-
by a number of source lines placed in the centre of each lane, or
-
by a single source line in the middle of a two way road, or
-
by one source line per carriageway in the outer lane of multi-lane roads.
CadnaA, uses variant 3 by default.
In order to use variant 1, enter as many parallel road objects as there are lanes, each road object having a road width of 0 m (causing a single emission line in each case). In order to apply variant 2, deactivate the option „Calculate outer Lanes separately“ on the „Road“ tab (see CNOSSOS-EU).
The emission line/s is/are segmented with each segment being replaced by a point source. The source height is 0.05 m above the road surface for all vehicle classes. The height entered in the dialog Geometry is the height of the road surface.
Speed Correction
Traffic speed can be specified for "Autos" and - if activated - for "Trucks" separately (in km/h). The speed limit entered for "Autos" will be considered for cars and motorcycles (incl. category 5) while the speed limit entered for "Trucks" - if any - will be considered for medium and heavy trucks. With the limit entered just for "Autos" (i.e. option "Trucks" deactivated) the value applies to all types of vehicles (i.e. no intrinsic speed limit for trucks).
Consequently, there is no road-specific speed limit for motorcycles. However, a vehicle class specific speed limit for motorcycles can be entered on the „Road“ tab (see CNOSSOS-EU).
For all categories, with speeds less than 20 km/h the sound power level as for vm=20 km/h is used.
Button DEN
see Common Input Data, Button DEN
Road Gradient (%)
The effect of road gradient is considered in the propulsion noise only, where a steady speed is assumed. The correction term ΔLWP,grad,m is a function of the slope s%, the vehicle speed vm (in km/h) and the vehicle class m.
Road Surface
Select the road surfaces via the drop down menu. The dropdown shows the data from the local library (if available) followed by the data from the default library, see Road Surfaces
Library Access
gives access to the global library of road surfaces