Are German Roads As Quiet As German Cars?

11/26/2007

On our last stops in Europe, the CP Tech Center visited 6 sites in Germany. Two of these sites are of particular interest as they allowed for a “side-by-side” comparison of various concrete pavement texturing techniques. These sites include low-noise pavement test sections on the B56 near Düren and on the A4 near Röhe. If you haven’t been to either place, click below for a free tour on Google Maps:

Google Earth Thumbnail of GE02 Test SectionsGoogle Earth Thumbnail of GE05 Test Sections

GE02 (B56-Düren) — GE05 (A4-Röhe)

On Site GE02, we tested 4 unique textures / sections:

Exposed aggregate on pavement

Section A – Exposed Aggregate – CRCP

Exposed aggregate on pavement section B

Section B – Exposed Aggregate – JCP

Diamond grinding on pavement

Section C – Diamond Grinding

Broom drag pavement texture

Section D – Broom Drag

The results for the levels and spectra from the OBSI measurements are as follows:

A weighted total OBSI level chart A weighted OBSI Level Chart - Spectra

 

Of particular interest on all of the European test sections has been the contribution of the joint “slap” to the overall levels (and to some degree, the corresponding bias in the average spectra). Since all of the measurements were recorded for subsequent postprocessing, the effects of the joints can be separated from that of the texture. To illustrate the significance, the following plot shows a trace of the average (overall) OBSI level of Section D. In this plot, you will note the quieter “texture” level that is periodically interrupted by a “slap” event at the joint (in this case, every 5m). For clarity, the gridlines have been lined up at the approximate joint locations:

A-weighted OBSI Level Chart - Joints

Meanwhile, on the A4, three different textures were evaluated, as follows:

Exposed aggregate pavement (5mm nominal)

Section A – Exposed Aggregate (5mm Nominal)

Exposed aggregate pavement (8mm nominal)

Section B – Exposed Aggregate (8mm Nominal)

Burlap drag texture pavement

Section C – Burlap Drag

At the time of testing, Sections A and B were approximately 7.5 years old, and Section C was constructed 6.5 years ago. The levels and spectra for these three sections can be found here:

 

A4 pavement Test Section Chart - Total Third octave band center frequency pavement texture chart - spectra

The project team would like to thank the Bundesanstalt für Straßenwesen (BASt) for their very generous assistance during this effort, especially that of Dr. Igor Müller, Mr. Stefan Höller, and Mses. Beata Krieger and Nina Sliwa.