Archive for June, 2009

Venice to Ljubljana: A Drive-by Noise Barrier Tour

Thursday, June 11th, 2009

by Doug Barrett

Last month I had the opportunity to make the 2.5 hour drive from Venice, Italy to Ljubljana, Slovenia.  First rounding the broad lowlands of the northern Adriatic and then passing through the foothills of the Julian Alps, the Autostrada spans diverse cultures and landscapes.  As one  travels farther east, steeples in small towns change from Italianate towers to onion-shaped domes and the terrain transforms from coastal to mountainous.

While many visitors may focus on the centuries-old villages, ancient ruins, and timeless mountain vistas, the drive also offers quite a sample of modern highway noise barriers.  My fabulous spouse not only tolerated, but (when I was driving) even contributed to a high-speed windshield survey of northern Italian and Slovenian noise barriers.  Several features set these noise barriers apart from those typically found along highways in the United States:

Widespread use of sound-absorptive materials:  Although some U.S. transportation agencies commonly use sound-absorptive materials to minimize the effects of reflected sound (Virginia DOT and New York State DOT come to mind), other state DOTs do not.  Also, while cement-based absorptive materials are popular for highway barriers in the United States, metal panels were the most popular in this region.


Use of tilted noise barriers: Tilting noise barriers back from the highway is another strategy to reduce multiple reflections of sound between parallel barriers.  This technique, although rare in the U.S., was common here.  Sometimes entire barriers were tilted, other times, each individual panel, or just the upper portion of the barrier was angled.


Transparent materials: In some locations, scenic views were preserved by using transparent panels.  On many barriers, only the top portion was transparent, typically with the obligatory hawk decal to reduce bird strikes.


I found the mixing and matching of these features to be especially interesting.  Because the transparent materials are not sound-absorptive, often they were paired with sound-absorptive lower panels.  In some cases, only the transparent upper portion was curved or tilted.  One barrier included a sound-absorptive lower section combined with a transparent upper section, bent towards the road to increase the barrier’s effective height.  The entire structure was capped by a sound-absorptive roll-top, also intended to improve the barrier’s noise reduction benefit.


The Waterpark Capital of the World!

Thursday, June 11th, 2009

by Mary Ellen Eagan

I spent the weekend in the Wisconsin Dells, celebrating my in-laws’ 50th wedding anniversary.  As a waterpark virgin, I thought I’d report on my experience.  It would require an entire blog post to explore the in-laws, or the Midwest. (I always forget how nice these people are – here I am at DTW, browsing at Borders– well actually, trying to keep the kids from killing each other during our four-hour layover by reading up on the Jonas Brothers and latest in the Twilight/teenage-mutant vampire sex saga – and the sales clerk just will not stop talking.  “What’s your problem?” I want to ask, and then it hits me – I’m in Michigan!)

Chula Vista Waterpark, Wisconsin Dells

Chula Vista Waterpark, Wisconsin Dells

Anyway, back to the Waterpark Capital of the World®.  Because this is Wisconsin, and the weather can be (and was) 50 degrees in June, we spent our weekend at the indoor waterpark.  At check-in, I noticed a sign that read something like, “In order to protect and enhance our environment, we are charging a $2 per day ‘green fee'”.  It was then that I started noticing the environmental nightmare of this place:

  • First of all, there are hundreds of thousands of gallons of water being used on a daily basis, mostly transported around by pumps and machines of enormous proportions.
  • This water, splashed around by wave machines, water cannons, and the like, creates rainforest-like conditions.  Combine that with the airborne byproducts of pool-water sanitizing chemicals, and indoor air quality is something you don’t want to think about.
  • Finally, the noise.  I felt a bit like the Grinch in Who-ville (“That’s one thing he hated! The NOISE! THE NOISE! THE NOISE!”) but I swear the noise levels must have exceeded OSHA standards.  There are very few times I wish I had a sound level meter on-hand; this was one of them.

Back in our room/condo, there was a jacuzzi (into which Greta proceeded to pour an entire bottle of dishwashing liquid – someone’s having bubble baths this week!), the usual teeny-tiny bottles of shampoo, and not a single energy-efficient light bulb.   I kept asking myself what they could possibly by spending my $2 on.

When I got home, I tried to do some research on environmental impacts of waterparks, and did not find much.  I did learn though, that there is a LEED-Certified waterpark in Indiana.  This seems about as oxymoronic as ‘sustainable aviation’, but whatever.

The kids had a blast.

A Night at the Volksoper

Monday, June 8th, 2009

by Lance Meister

My wife and I recently took a trip to Europe to visit her family and get some culture.  We spent three days in Vienna, and one night we went to the opera to see La Boheme.  We went to the Volksoper (the people’s opera), which could be classified as the second best opera house in Vienna, after the Stadtoper (the state opera).  This was definitely a classic opera house, with the red velour seat covers and the boxes up both sides of the stage.

We took the U-bahn (the subway in German) to the opera house.  Interestingly, it looks like the Vienna subway is a wide gauge (the distance between the rails, the standard is 4′ 8 1/2″, and it looks like Vienna might be 5′).  When we got off the train, about a block from the opera house, we saw a streetcar running down the street next to the Volksoper.  It’s impressive to see how much public transit European cities have.

We went in and found our seats in the balcony.  (Interesting acoustics note:  If you’re down in the lower seats close to the stage, you might be able to see better, but the seats in the balcony have some of the best acoustics in the house.  They’re also cheaper.)  The opera started, and almost immediately I noticed a very low-frequency rumbling noise.  At first, I thought it might be a thunder-type sound effect from the orchestra, but even with my limited knowledge of both German and opera, it didn’t fit the scene.  The sound went away, but then it came back about 5-10 minutes later.  I realized that what I was hearing was ground-bourne noise (or GBN as we call it) from the streetcar on the street outside.  Now, I’ve been in the business for many years, but I think this was the first time I had really experienced GBN, and been seriously bothered by it.  The noise, even when the orchestra was playing and the singers were singing, was clearly audible, due mainly to the very low frequency of the noise.  It was definitely interfering with my enjoyment of the performance.

Now, you may ask, what is GBN, and how could the streetcar be causing it?  GBN is caused by ground-bourne vibration.  Vibration propagates from the steel wheels on the steel rail, through the ground, into a building, and causes room surfaces to shake and radiate noise; much like a speaker generates noise by vibrating the diaphragm.  Because vibration is very low frequency, the radiated noise is also low frequency, and produces a very low rumbling sound.  Most of the time, this GBN is inaudible, and is masked by airborne noise.  However, in  two cases, GBN may be heard.  One is when the train is in a tunnel, and there is no airborne noise to mask the GBN.  The other is when a building is very well insulated against airborne noise, such as a recording studio, a theater, or… an opera house!

What really surprised me was than in a place like Vienna, where they value their cultural spaces, and where noise and vibration is taken seriously, they wouldn’t have solved this problem a long time ago.  Both the opera house and the street car appear to have been there for a long time,  so this has to have been occurring for many years.  However, GBN is a relatively easy problem to solve. While GBN is low frequency noise (100-400 Hz), it is caused by what we consider high frequency vibration.  Vibration  (and GBN) mitigation is almost universally effective at higher frequencies (above 60 Hz), so most types of mitigation would be effective at reducing the annoyance from the GBN in the opera house.

So for me, the tragedy was not the death of the heroine at the end of the opera, but the fact that the performance was spoiled by a GBN problem that could be solved relatively easily.

Public Participation

Friday, June 5th, 2009
by Mary Ellen Eagan
Last night I participated in a public workshop on the TF Green Airport Expansion EIS.  See coverage herehere, and here.
Hundreds of local residents attend the Federal Aviation Administration's public meeting on the proposed runway expansion at Green Airport, at the Crown Plaza, in Warwick, Wednesday.  The Providence Journal / Ruben W. Perez

Hundreds of local residents attend the Federal Aviation Administration's public meeting on the proposed runway expansion at Green Airport, at the Crown Plaza, in Warwick, Wednesday. The Providence Journal / Ruben W. Perez










An estimated 400 people turned out, mostly to find out if their homes are eligible for mitigation (acquisition or sound insulation) as a result of a proposed runway extension at the airport.  These folks have been waiting for a very long time for this environmental process to conclude.  Imagine, if you can, holding off on routine home repairs (new roof, replacement windows) for 10 or more years while FAA sorts out which of a zillion alternatives it will finally choose to build.  Or maybe not.

I am always astounded by how polite and grateful folks are to get information; at the end of the day, most people are just looking for honest, straightforward answers to their questions.  And it’s our job to provide them.  I am often equally astounded by callous indifference on the part of the bureaucrats and/or consultants sharing the information – just another public meeting in another city.  I was proud last night to feel as though everyone on our large team took our jobs seriously, provided thoughtful and sincere answers, and respected the perspectives and feelings of the folks living with the impacts of the airport and its possible future.

Many people thanked me.  That’s the kind of job satisfaction I work for.