Second campaign

Following the implementation of the statements and the measure of an initial campaign, a second campaign was undertaken to measure the acoustic behaviour. Like the first campaign, the sound indicators used are as follows:

• Proximity Method (CPX Test -Close ProXimity method). This method is standardised under ISO/CD Standard 11819-2. “Acoustic. Measurement of the influence of road surfaces on traffic noise. Part 2: Proximity Method.
• Statistical Method of the Passage of Vehicles (SPB Test- Statistical Pass-by noise). This method is standardised under Standard ISO 11819-1. “Acoustic. Measurement of the influence of road surfaces on traffic noise. Part 1: Statistical method of the passage of vehicles”.

CPX (left) and SPB (right) test

Following the analysis of the results obtained from the second acoustic assessment, it is confirmed that such LIFESOUNDLESS mixtures are able to reduce the road noise generated by the contact made between the tyre and the road surface and this property is maintained in general terms during the year of their implementation. The key results and conclusions are shown below:

1. Noise levels achieved in the second campaign from the CPX test

• The expected noise reductions were achieved and maintained. The proposed objective with the new LIFESOUNDLESS mixtures was to reach about 89-90 dBA at 50 km/h and 97dBA at 80 Km/h in the CPX test (reduction of 3dBA with respect to the road before the action).

2. Benefits achieved from the CPX test regarding the initial situation

• The average sound reductions with the SPB method were quantified at 5dB on the A-8058 (Scene 1) and 9dB on the A-376 (Scene 2) in the first campaign, maintaining this in the second campaign also. It has been demonstrated that with SOUNDLESS roads it is possible to reduce to 4dB @ 50 km/h and 7dB @80 km/h with respect to the existing solution within a one-year period.

3. Results measured SPB

• It has been demonstrated that SOUNDLESS roads reduce by up to 3 dB @50km/h and 5 dB @80 km/h with respect to a new AC16 surf road in the year analysed.
• The acoustic variability in the paved sections is kept within the orders of the first campaign 1 dB.
• The LIFESOUNDLESS mixture, with the addition of 1% plastic (mixture spread in Scene 2: A-376) continues having the greatest noise reduction. However, the most silent mixture continues to be the one with 1.5% NFU powder (mixture applied in Scene 1: A-8058). In conclusion, the presence of additives helps stabilise a larger amount of bitumen in the mixture, thereby allowing less road noise to be generated, combining the maintenance of the structure with the traffic loads.
• The estimate of the population affected tells us that the solution adopted is fairly well suited to the problems affecting the area.
• No noteworthy surface defects have appeared on the road in during the first few months.