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SonRoad

Emission Parameter

According to the Swiss road noise model „SonRoad“ the A-weighted sound power level LwA in dB(A) emitted by the two vehicle types autos and trucks calculates from Heu-2004:

  • for autos:

\(L_{\text{wA,autos}}=28.5+10 \lg(10^{0.1(7.3+35 \lg v + \Delta_{BR})}+10^{0.1(60.5+10 \lg (1+(\frac{v}{44})^{3.5})+\Delta_S)})+\Delta_{BG}\)

  • for trucks:

\(L_{\text{wA,trucks}}=28.5+10 \lg(10^{0.1(16.3+35 \lg v + \Delta_{BR})}+10^{0.1(74.7+10 \lg (1+(\frac{v}{56})^{3.5})+\Delta_S)})+\Delta_{BG}\)

with

  • v: speed of autos or trucks, in km/h

  • ΔBR: correction for roll noise component on road surfaces (tabulated, see below), in dB(A)

  • ΔBG: correction for total noise component on road surfaces (tabulated, see below), in dB(A)

  • ΔS: gradient correction, in dB(A)

Dialog Road (for SonRoad)

In SonRoad, the emission is based on A-weighted sound power levels, while the calculation of propagation occurs in one-third octave-bands, in CadnaA converted to octave band levels and A-weighted levels.

The A-weighted sound power per unit length L’wA in third-octave bands results from:

\(L'_{wA}=10 \lg (\sum_{j=0}^{23}(\frac{N_{autos}}{v_{autos}}10^{0.1(L_{wA,autos}+Y(j))}+\frac{N_{trucks}}{v_{trucks}}10^{0.1(L_{wA,trucks}+Y(j))}))-30dB+MK+K_1\)

with

  • Nautos, Ntrucks: number of autos/trucks per hour

  • vautos, vtrucks: speed of autos/trucks, in km/h

  • Y(j): third-octave values of the reference spectrum (see below), in dB(A)

  • j: running number of third-octave

  • ML, K1: model & level corrections (see below)

Reference Spectrum

The values X(j) represent the A-weighting spectrum. As the emission data was measured on hard ground the final spectrum Y(j) results.

j Frequency(Hz) X(j) in
dB(A)		 Y(j) in
dB(A)
1 100 -20 -24.3
2 125 -20 -24.3
3 160 -18 -22.3
4 200 -16 -20.2
5 250 -15 -19.1
6 315 -14 -17.9
7 400 -13 -16.6
8 500 -12 -15.1
9 630 -11 -13.4
10 800 -9 -10.3
11 1000 -8 -7.6
12 1250 -9 -6.6
13 1600 -10 -7.5
14 2000 -11 -10.9
15 2500 -13 -14.5
16 3150 -15 -15.5
17 4000 -16 -15.1
18 5000 -18 -18.7

Specification of Emission

MDTD

CadnaA offers to introduce traffic data based on Mean Daily Traffic Data (MDTD), though not available in SonRoad originally. In this case, the number of vehicles per hour N and the percentage trucks/buses eta (%) is calculated for the road type „Switzerland“ according to the specifications in the Swiss road noise standard STL-86 BAFU60-1987.

Road Type Day (6-22 h) Night (22-6 h)
N (veh/h) Eta (%) N (veh/h) Eta (%)
Switzerland 0.058 MDTD 10 0.009 MDTD 5

Exact Counts

This option enables to enter the five hourly traffic figures N and percentage of heavy vehicles eta (%) for the time periods D/E/N.

L’wA dB(A)

direct input of L’wA in dB(A)

Diurnal Pattern

see Common Input Data, Diurnal Pattern

Model Correction MK

The model correction MK can - as already available for STL86 BAFU60-1987 - be entered for each road and time periods D/E/N individually.

Level Correction K1

The level correction K1 is a low traffic correction according to:

  • -5 for N<31.6
  • \(10 \lg (\frac{N}{100})\) for 31.6 <= N < 100
  • 0 for N > 100

with

  • N: total number of vehicles per hour

Speed (km/h)

The speed correction in CadnaA is based on the speed entered (whether it complies with an actual speed limit or not).

Source Geometry

The source height in SonRoad is 0.45 m above ground.

Road Surface

The table below lists the road surface corrections for the total noise (ΔBG) and for the roll noise (ΔBR).

Surface Type ΔBG dB(A) ΔBR dB(A)
asphalt concrete AC 8,11,16 (also AB 10,11,16) 0 0
concrete (depending on age and condition) +2 0
porous asphalt PA 8,11 (formerly drain asphalt DRA 10,11) for speeds v > 70 km/h -4 0
mastic asphalt MA 8,11,16 (formerly GA) 0 0
rough asphalt AC MR 8,11 (formerly also Macro-Rugeux MR 6,11) -1 0
surface treatment OB 3/6 0 0
surface treatment OB 6/11 +1 0
stone mastic asphalt SMA 6 -1 0
stone mastic asphalt SMA 8,11 0 0
chipped mastic asphalt SPA 6,8,11 0 0
asphalt concrete TA 10 0 0
asphalt concrete TA 16 +1 0
pavement (Note - Larger individual spread is likely.) 0 +6

Road Gradient (%)

A positive road gradient g (i.e. uphill) results in the level correction:

\(\Delta_S = 0.8 * g\) for g > 0%

Roads with negative slope (i.e. downhill) receive no correction.

Correction for Multiple Reflections

Multiple reflections within an urban road can be corrected with the procedure according to RLS-90. For further information see RLS-90, Correction for Multiple Reflections.