Noise Barrier Modfied

As I wrote a short time back, the commercial interests of Gopher Electronic's owner appears to have some over-riding influence on the barrier construction. The current design, as of November 27, per Jennie Read, PE, North Area Engineer - Ramsey County, (jennifer.read@state.mn.us) is described in the figure below:

I have, as usual, a couple of concerns. It makes sense to begin to taper the wall down as it approaches Little Canada Road. A visual obstruction for vehicles from the west turning south onto the I35E entrance would be a safety hazard. However, terminating the wall at the current location ignores the health and quiet of our neighbors on Australian Avenue. The two issues that will cause their noise levels to be untouched (regardless of the oddly derived MNDOT estimates) are the gap left between the noise source (I35E) and the reflection caused by the earlier east side noise wall. The photo below illustrates that the east wall is nicely lined up to reflect noise from that side of the freeway into the neighborhood directly across the intersection.

Simply extending the wall to match the new east side barrier is not enough to correct the damage done by the original (and poorly considered) noise barrier design. While it might be inconvenient for the business owners to have to install higher signage to be visible to the tiny fraction of drivers who will be looking for signs while negotiating a hazardous section of freeway, the cost to the homeowners should come first for both MNDOT and the City of Little Canada's local government.

Having seen the original noise level estimates made by MNDOT which were used to justify why noise barriers were not recommended when the freeway was expanded, I'm unimpressed by the random numbers their "engineers" have applied to expectations of noise reductions in the neighborhoods. The closer the properties are to the noise barrier, the more effective the barrier will be. Even MNDOT "experts" should know this fact.

Honestly, the more I see these characters abuse science, the more I am convinced of Thomas Huxley's condemnation of the three classes of witnesses, "liars, damned liars, and experts." At least with these new estimates in hand, I will have data to work with in collecting measurements over the next few seasons before the wall is constructed. After the wall is built, it will be interesting to hear the MNDOT excuses for why their numbers, again, failed to approach reality. Before the previous I35E expansion and noise wall construction, the MNDOT optimistic guesses regarding the effects on our property defied logic and science and were, as expected, wrong. Instead of "less than 3dB" of change in the abusive noise levels on our properties, the new traffic expansion increased levels by 5-9dBA and 8-14dBC.

The Little Canada residents living along the south end of the existing west side wall (1o-3o on the MNDOT map above) have voted against the extension of the wall. I suspect it is because they are receiving as much benefit from the existing trees as they expect from a new wall. Due to medical issues, I was not able to attend the November 28 City Council meeting where they expressed their opinions. However, it will be critical for the city and residents to carefully monitor any MNDOT "enhancements" to the existing tree protection, if that becomes part of the plan. When MNDOT planted 4' trees on the west side (near the 1n location on the MNDOT map above), the state's employees cut down several existing 20' trees to "make room" for the new starter plants. Obviously, that was counter-productive and should not be repeated.

"Unweave the Weave" Landscaping

The February-March edition of the Little Canada Le Petit Canadien mentioned that about $250,000 will be made available for landscaping to recover some of the damage done by the increased width of the freeway and to moderate some of the noise that came with that freeway traffic. All I can say is, "it's about time." I've monitored the sound pressure level in my backyard during rush hour and the noise level far exceeds EPA and OSHA safe limits; well into the low 90dBSPL territory.

The Canadien article suggested that the City Council has "focused on the area between I-35E and West Savage Lake in an attempt to create some natural barriers to the sound and view coming from the freeway." This is a solid approach. The extended barriers on the east side of the lake have reflected additional noise in our direction, which makes safely enjoying our neighborhood and yards impossible during much of the day. Hopefully, the character MnDOT used as an "acoustic expert" won't be involved in this analysis, since pretty much all of his guess-timates about the effects on our neighborhood from the freeway expansion and the noise barriers were so far off I'd be surprised if that guy ever attended a science class at any time in his life.

Sound absorption is a much better tactic for silencing noise than obstruction. The noise barriers have a limited effectiveness, based on height, length of the barrier, distance from the noise source and the target clients, the noise bandwidth, and the mass of the materials used for the barrier. Absorption actually converts sound energy to heat; not a lot of heat, but that energy is no longer sound. Noise doesn't bounce off of conifers. Instead, the air motion pass through the branches and leaf tissue and moving those obstacles converts sound to motion and heat.

Of course, the trees will absorb some of the carbon dioxide, lowering pollution levels. In all, this is a plan my wife and I have been advocating for almost a decade and I'm glad to see the city and state buying into it. We should all give Joel Hanson a call at 651/766-4040 or email at joel.hanson@ci.little-canada.mn.us and get the city behind this idea. With decent sized plantings, almost immediately we could have a substantially more quiet neighborhood. In a few years, this could be our view of the freeway.