In the fall of 1996, near the small town of Herne (click HERE for Google Map), an investigation was initiated with the task of seeking out so-called “Noiseless Cement Concrete Pavements”. Sponsored by the Environment and Infrastructure Department of the Ministry of the Flemish Community, test sections of six unique pavement types were constructed along the N255 highway. This two-lane rural highway was constructed with the following surfaces:
- Surface A: Dense-graded hot-mix asphalt “AB-2 0/10 (+10/14)” – with a maximum aggregate size of 14 mm.
- Surface B: Exposed Aggregate Concrete 0/7 (maximum aggregate size of 7 mm)
- Surface C: Porous Asphalt “ZOAB 0/14” (14 mm max aggregate size)
- Surface D: “Very” Porous Concrete 0/7
- Surface E: Stone Matrix Asphalt (SMA) 0/14
- Surface F: SMA 0/10
Three reports on these sections have been developed by the Ministry. Download them here:
These reports include detailed information on the materials and construction used on these sections. Acoustical measurements were also made periodically after construction, along with friction measurements.
The question that the National CP Tech Center wanted to address was what has happened since 1999, and how does this compare to the US experience? Of course, the two sections of most interest were the porous concrete and exposed aggregate concrete sections. See photos below (click on a photo to expand it):
With the much-appreciated assistance of FEBELCEM and the Flemish Ministry Road and Traffic Administration, measurements for noise using OBSI were conducted in October 2007. Due to speed restrictions, data at multiple speeds were collected to determine the relationship between that and noise level. From these measurements, levels were derived at 60 mph that could be compared to other measurements being collected in the program. The results for each of the six test sections were summarized in both total OBSI levels and corresponding spectra. These can be downloaded here:
So what has changed in the last decade? Judge for yourself. Keep in mind that the levels measured ten years ago were using a different measurement system (not OBSI, as we have measured here), therefore they cannot be directly compared. However, the levels relative to each other are worth noting.
The CP Tech Center and the project sponsors would like to thank Messrs. Luc Rens and André Jasienski FEBELCEM and Mr. Chris Caestecker of the Flemish Ministry, as well as others within these organizations who contributed. We would also like to thank Dr. Luc Goubert of the BRRC for his assistance.