So far, a lot has been reported on the recent suite of testing in Europe conducted by the National Concrete Pavement Technology Center. It was also reported that this work was done in concert with an ambitious testing program done in the US where, to date, over 1200 test sections have been evaluated for noise, texture, friction, and smoothness.

The question must be asked: how do US practices of texturing concrete pavements compare to those used in Europe in terms of tire-pavement noise?

First, it must be said that a lot more must be considered when comparing pavement textures. A fair comparison must include factors such as friction, durability, and cost, among others. It has been shown, however, that virtually all nominal concrete pavement textures - both in Europe and in the US - can be built low-noise and yet still excel in these other areas.

OK, so just how quiet are US concrete pavement textures?

There is a lot of variability in measuring noise. Some due to the measurement, but still a lot due to the variability in and among the pavements. With over a thousand test sections, characteristics of "populations" of similar pavement textures begin to emerge. The following figure includes a normalized depiction of the populations of the four most commonly used textures in the US: diamond grinding, drag textures, longitudinal tining, and transverse tining:

Click on the image above or HERE to enlarge the image.

Note the levels - note the variability in the levels. The quieter of all concrete pavement textures are those that are diamond ground and with drag surfaces. Longitudinally tined also have many quieter sections, but also have more variability and can therefore also be noisy. The noisier ones are likely those that are worn and/or constructed with a more aggressive texture. Transverse tining has the most variability with some quieter sections (almost all of which have small - typ. 1/2" - spacings), but also very loud sections with most being randomly spaced tines with large gaps (typ. 1 to 3") between the grooves. Again, wear and quality of the concrete and construction are big factors in where a particular pavement might stand within this population.

With this information, we leave it to you to compare to the European practice as documented below. But as you compare the US to Europe - and as you compare among the various US texture types - keep in mind what other factors are also important.

In the last blog entry, a preview was given of the use of Google Earth as part of this project. The measurement results from each of the sites are being ported to Google Earth for both visualization and interpretation. Moving averages of the On-Board Sound Intensity are calculated with a 0.5-second window (44 ft. at 60 mph). The result is a trace that characterizes the test variability along the section. Overlaying this on top of the terrain and aerial images in Google Earth allows for a better understanding of this variability.

The following three images illustrate three of the test sections. Click on any of the images to expand on it.

Austria Site AT05

Belgium Site BE01

Netherlands Site NL02

If you want to take a test drive of Google Earth for yourself, first make sure you have the latest version installed, which can be downloaded by clicking HERE.

Then click HERE to download the file for AT05 illustrated above.

Have a nice flight!

 

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 on the images below for a free tour:

GE02 (B56-Düren) --- GE05 (A4-Röhe)

On Site GE02, we tested 4 unique textures / sections (click on small images to expand):

• Section A - Exposed Aggregate - CRCP
• Section B - Exposed Aggregate - JCP
• Section C - Diamond Grinding
• Section D - Broom Drag

The results for the levels and spectra from the OBSI measurements are as follows (click on image to expand):

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 seperated 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:

(Click on the above image or HERE to expand)

Meanwhile, on the A4, three different textures were evaluated, as follows (click on images to expand detail):

• Section A - Exposed Aggregate (5mm Nominal)
• Section B - Exposed Aggregate (8mm Nominal)
• 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 (click on the images to expand):

 

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.

So far, a lot of preliminary noise results have been reported. However, one of the key elements of the CP Tech Center testing in Europe was texture measurements using the Robotic Texture (RoboTex) Measurement System. Due to the need for traffic control, RoboTex measurements were not possible on all of the sections, however 8 exposed aggregate concrete sections were tested in total: 5 in Austria, 2 in Belgium, and 1 in Germany.

In summarizing the texture measurements, "cards" have been developed. On each card, you will find representative photos of the various pavements, along with a 3D image of the RoboTex data. Summary metrics are also given including the average Mean Profile Depth (MPD) and a spectral analysis of texture per the most current draft of the ISO 13473-4 specification. Average On-Board Sound Intensity Levels (A-weighted, ref 1 pW/m²) are also provided for quick reference.

To view any card, simply click on the small image below.

Be sure to collect them all!

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 and can be downloaded here:

Click images above to download PDF reports or here:

April 1997 REPORT --- April 1999 REPORT --- October 1999 REPORT

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):

Exposed Aggregate - PHOTO 1 - PHOTO 2

Porous Concrete - PHOTO 1 - PHOTO 2

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:

OBSI Measurements - TOTAL LEVELS - SPECTRA

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.

With a number of comments received so far on the posts from the European testing being conducted by the National CP Tech Center, it seemed appropriate to fulfill another (quite logical) human sense... hearing.

From the results posted so far, 7 sound clips have been prepared to form a "listening experience" of some of the European pavements: 3 from Austria, 2 from Belgium, and 2 from the Netherlands.

Total OBSI levels and corresponding third-octave spectra from these sections are summarized together below (click on either image to expand):

Each sound clip was prepared by sampling approximately 5 seconds of OBSI data. The left channel (ear) is a measurement taken near the leading edge (front) of the test tire. The right ear will hear a measurement from the trailing edge (rear) of the tire. Some filtering has been performed to better reproduce the sound as one might hear it at these locations (and still minimizing the effect of wind noise).

To listen to these sound clips, simply click on the following links. If they do not play, you might need to download them first, and play them seperately.

File AT03.mp3 (Austria, 8 mm Exposed Aggregate, 7 yrs old)

File AT05.mp3 (Austria, 11mm Exposed Aggregate, 6 yrs old)

File AT06.mp3 (Austria, 8 mm Exposed Aggregate, 15 yrs old)

File BE02.mpg (Belgium, 20 mm Exposed Aggregate, age TBD)

File BE03.mpg (Belgium, 6.3 mm Exposed Aggregate, age TBD)

File NL01.mpg (Netherlands, 8 mm Exposed Aggregate, 1.5 yrs old)

File NL02.mpg (Netherlands, Porous Concrete, 1.5 yrs old)

Don't forget to load them up on your iPod for maximum enjoyment!!!!

The CP Tech Center team has recently completed testing in the Netherlands, where three unique sites were visited. The first includes a series of 41 unique test surfaces, constructed as part of the Innovatieprogramma Geluid (IPG) - a Dutch program with the objective of reducing road and rail noise. The other two sites included a single concrete pavement surface each.

The first, NL01, is an exposed aggregate concrete pavement that was constructed on N285 near Zevenbergen, HERE. Built in 2006, the concrete mix includes a "4/8 mm" aggregate, which was selected based on the results of a low-noise concrete pavement experiment conducted in 2000 by the Noord-Brabant Province, Dutch Association of the Netherlands Cement Industry (VNC), and the Dutch Information and Technology Centre for Transport and nfrastructure (CROW). Photographs of this surface are below, which can be clicked on to enlarge.

The next section was a very interesting one, as it is innovative in a number of ways. The section is a test section of a precast concrete pavement technique called Modieslab. Orginally developed under the Roads to the Future program in the Netherlands, this section was built more recently - in 2006 - as a means to demonstrate this technique under heavy, high-speed traffic. Sponsored as well by the IPG as a "third generation road surface", the section is located at the junction of the A12 and A2 motorways near Utrecht, HERE. The section consists of 3.6- x 7.2-m precast concrete panels that include a porous concrete surface. Photos of the section and the surface are found below (click to enlarge).

The on-board sound intensity levels were evaluated using the new SRTT tire at 60 mph. The resulting levels and spectra for these two sections can be found below.

(Click on the figure above or HERE to expand)

(Click on the figure above or HERE to expand)

As can be seen, the OBSI level for the porous concrete surface on the Modieslab is very low - just over 96 dBA. This makes it the lowest level of all of the concrete pavement surfaces measured so far by the CP Tech Center team.

As mentioned elsewhere in this blog, this measurement program can be viewed as "NITE 2", or complementary to the Caltrans/FHWA-sponsored NITE study previously conducted by Dr. Paul Donavan of Illingworth & Rodkin. While measuring noise on numerous surfaces in Europe in 2004, a diamond ground porous concrete surface was found to be about the same level as this Modieslab section. Unfortunately, the section measured under NITE experienced durability problems, and has since been removed. However, it can be concluded from both studies that very quiet concrete pavement surfaces are possible.

The exposed aggregate section on N285 is also worth mentioning as both the level and spectra are "in between" the experiences seen in Austria and Belgium. The aggregate size is - possibly not coincidentilly - somewhere in between as well.

The team would like to thank a number of folks that helped us tremendously in the Netherlands. The IPG staff was very cooperative, including Messrs. Ruud Nijland, Guido Debeus, Thijs Bennis, and Peter The. Mr. Marc Stet of VIA Aperta and Dr. Gijsjan van Blokland of M+P were also instrumental in establishing the necessary contacts. In addition, Steef van Hartskamp of the Provincie Noord-Brabant should be thanked. Finally, Mr. Rob Snijders of Arcadis and Noud van Deurzen of BETONSON have been very helpful in providing support information for the Modieslab site.

Thanks to the assistance of FEBELCEM and the Road and Traffic Administration, testing in Belgium was completed last week with the evaluation of three test sites. Two of these sites were located along the N49 (E34) highway - the primary artery between Antwerp and Brugge in the northern part of the country (Flemish region). Both sites were constructed with exposed agrgegate concrete surfaces.

One site, labeled BE02, is located near the town of Zelzate or more specifically, HERE. It was constructed as a 23-cm Continuously Reinforced Concrete Pavement (CRCP) inlay of an existing asphalt section. The concrete aggregate consisted of 4 fractions: a blend of two porphyry coarse aggregates and two sands. The maximum aggregate size is 20 mm. Here are a coupleof photographs of these surfaces. Click on either image to view more detail:

 

The second site, BE03, is just outside Antwerp near the town of Melsele, HERE. It was reportedly constructed as a two-lift concrete pavement using techniques similar to the those used in Austria. The top lift on this section used a much smaller coarse aggregate though, with a maximum aggregate size of 6 mm. The following are two photographs of this surface. Again, click on either image to expand it:

The results of the On-Board Sound Intensity testing of these two pavements was, as expected, very different.

Theory tells you that the concrete with the smaller aggrgeate should fare better in terms of measured sound levels. The measurements made under the National CP Tech Center program validated this fact. In fact, the OBSI level of the exposed aggregate surface on BE03 averaged 101.7 dBA compared to 105.3 dBA on the BE02 section.

(Click on the figure above or HERE to expand)

Comparing the spectra of the two sections is also revealing. The biggest differences can be found in the lower frequencies... those that "rumble". However, this too is not surprising in that the larger aggregates on the BE02 section lead to a corresponding increase in texture size. This, in turn, should lead to an increase in low frequency content.

(Click on the figure above or HERE to expand)

Testing in Austria is complete, and a total of six unique sites were evaluated for tire-pavement noise using OBSI and texture via RoboTex. Each of the sites was constructed using exposed aggregate concrete (some 8 mm maximum aggregate size, others 11 mm). The sites span a period of 15 years of construction.

OBSI data has been collected using the 16-in SRTT tire at 60 mph (97 km/hr), and a preliminary analysis has revealed that total OBSI levels are on the order of 104 to 106 dBA (ref 1 pW/sq.m). These levels are similar to those previously measured on exposed aggregate sections in both Michigan and in Montreal. To further reference these measurements, note that the quietest dense concrete pavement in the USA is on the order of 99 dBA, while the surfaces with the highest levels can be over 110 dBA.

Here is a little info about each of the Austrian sites:

• Site AT01 is located on the A2 near Vösendorf (south of Vienna). It was constructed in 2005/2006. Due to traffic levels, it was only measured using OBSI.
• Site AT02 is located on the A1 near Erlauf, approximately 60 miles West of Vienna. It was constructed in 2000 with 11 mm aggregate.
• Site AT03 and AT04 are in opposite directions of the A1 at the same location: near Tödling, about 100 miles West of Vienna. Both were constructed with 8 mm aggregate, but Site AT03 was constructed in 2000 and AT04 in 1998.
• SIte AT05 is on the A1 near Steindorf (Seewalchen am Attersee) - approximately 35 miles East of Salzburg. It was constructed using 11 mm maximum aggregate size in 2001.
• Site AT06 is on the A1 near Thalgau, 15 miles East of Salzburg. It is the oldest of the sites tested; constructed in 1992 using 8 mm aggregate.

The following figures reveal both the total OBSI levels and the corresponding spectra. Each site was approximately 1 to 1.5 km in length. To expand each figure, click on it.

(Click on the figure above or HERE to expand)

 

(Click on the figure above or HERE to expand)

Much appreciation is given to VÖZ, ASFINAG, and the various Autobahnmeisterei for their assistance in the measurements.

This last week, testing of pavement surface characteristics including tire-pavement noise and texture has begun in Austria. Two exposed aggregate sites were completed including a site south of Vienna near Vösendorf, and a second site near Salzburg. Four additional sites in Austria will be evaluated this week, before moving on to Belgium. Here is both a photo and postprocessed data from the RoboTex device showing the exposed aggregate on the A1 section near Salzburg:

On Sunday, January 13 (2008), a TRB workshop will be conducted at the Hilton with the intent to bring the transportation community up-to-speed on all that has been going on in designing and building quieter pavements around the country. The workshop will include a "Tire-Pavement Noise 101" session in the morning, following by a series of "we did it, and here is what we learned" presentations in the afternoon. More information can be found on the TRB Annual Meeting website, or more specifically at http://nrc40.nas.edu/meeting/Workshops.htm

The National Concrete Pavement Technology Center at Iowa State University has recently published the results of a the largest study ever looking at CPSC on pavements throughout the US and Canada. The report can be found at:

http://www.cproadmap.org/publications/Cackler_SCpart2_finalreport.pdf

While lengthy, the report includes an executive summary of the key findings, with the key one being that we have many examples of both safe and quiet in the existing concrete pavement inventory.

Unique was that the project was co-sponsored by the CP Tech Center, FHWA, and ACPA. The work published here continues to evolve, however, now as part of Pooled Fund project TPF-5(139). For more information, contact Paul Wiegand of the CP Tech Center at 515-294-7082 or by email pwiegand@iastate.edu.

Britpave (The British In-Situ Concrete Paving Association) recently announced the formation of EUPave - a consortium of concrete paving organizations in the UK, Belgium, Spain, the Netherlands, and Italy. The European Cement Industry Association is also a founding member. Expansion in the membership is expected, as the new organization will improve the efficiency of promotion and technical support throughout the EU member countries. More information will be made available soon on the website www.eupave.com

With one of the missions of the Surface Characteristics Track to collaborate with counterparts all over the world, this is a significant advancement worth following.

In two weeks, the National CP Tech Center will leave for Europe to conduct a round of Noise and Texture testing on pavements there. Beginning in Austria, they will then travel to Belgium, the Netherlands, and finally Germany. Dozens of pavements including exposed aggregate concrete and porous concrete will be tested. Innovative "low noise" solutions will also be evaluated. The measurement techniques that will be used are the same that have been used on over 1000 test sections to date in the USA and Canada. As a result, apples-to-apples comparisons can be made between European and North American pavement characteristics. The On-Board Sound Intensity measurements in Europe will be similar in scope to the NITE testing conducted by Dr. Paul Donavan in 2004. Texture will be measured with the innovative device termed RoboTex (Robotic Texture) Measurement System.

 

 

 

The next scheduled Noise 101 Workshop will be held September 21 in Montgomery, Alabama, sponsored by the Alabama DOT and FHWA Alabama Division. Ten additional workshops are now available and will be scheduled on a first-come, first-served basis.

This FHWA-sponsored workshop is your opportunity to bring noise and pavement experts together in order to help them understand each others’ concerns, see possibilities for integrating pavements into noise mitigation issues, and realize the need to work together to seek out solutions. This complex topic is presented in a simple and entertaining manner by world-renowned industry experts Paul R. Donavan, Ph.D. and Robert Otto Rasmussen, Ph.D., P.E. (TX).

Workshop Objectives:

• To educate noise practitioners on the fundamentals of pavements.
• To educate pavement practitioners on the fundamentals of noise.
• To understand tire-pavement noise and how it fits into the bigger picture.
• To understand the fundamentals of measuring and interpreting noise.
• To examine current practices for designing and constructing quieter pavements.

To Reserve Your Free Workshop:

Limited slots are still available and are scheduled on a first-come, first-served basis. To schedule a free workshop in your state, please contact:
Mark Swanlund
(202) 366-1323
email

or

Mark Ferroni
(202) 366-3233
email