Noise is in the ear of the listener.
That’s one conclusion to be drawn from a March 12 meeting to discuss noise reduction on Highway 280 in the St. Anthony Park area. About 20 people turned out to hear a presentation by MnDOT officials on what might be done to reduce noise levels on a road that has seen sharply increased traffic since the August collapse of the 35W bridge in Minneapolis.
The meeting was sponsored by a St. Anthony Park group called Citizens Concerned for Habitable Neighborhoods, in response to indications from MnDOT that any formal request for noise abatement should reflect neighborhood consensus.
Some consensus did emerge at the March 12 meeting. Residents said they’d like to pursue an asphalt overlay for the southern portion of 280, despite MnDOT officials’ skepticism that it would produce noticeable results.
MnDOT’s Chris Roy said the department calls a given measure “noise reduction” only if it results in a change of at least 5 decibels. He said that altering the surface of a roadway rarely results in a 5 db reduction; hence, MnDOT would need some other reason for an overlay, such as ease of maintenance.
MnDOT’s Peter Wasko added that overlays create their own problems. “Overlays deteriorate, sometimes fairly rapidly, especially with heavy truck traffic,” he said. “Then you’ve got potholes, which create their own kind of noise.”
Wasko noted that bridges, which constitute a sizeable portion of southern 280, cannot be overlaid, and he cautioned people about having unrealistic expectations from a roadway surface change. “Be careful what you wish for,” he said.
Many people at the meeting seemed unconvinced by MnDOT’s sometimes highly technical explanation of the effects of concrete “tining” (a finishing procedure that improves traction and drainage), the differences between sound volume and pitch, and the computer modeling the department uses to predict the effects of various noise mitigation procedures. In the end, they urged MnDOT to look further at an overlay.
Noise walls also came up for discussion at the meeting. Currently, 280 has a noise wall on portions of its east side. That wall was built a decade ago in response to neighborhood pressure, and a legislative mandate meant that the usual requisition procedures were circumvented.
That might be required again, since according to Roy, MnDOT’s funds for noise reduction are extremely limited. Wasko said it costs almost $2 million a mile to construct a noise wall, and there are about 265 sites in the metro area that could use one.
“Any neighborhood that wants a noise wall is competing with a lot of other neighborhoods,” he said.
Roy also pointed out that noise walls can’t be built everywhere. Such variables as visibility, slope and right-of-way requirements severely limit the potential to add sound barriers on 280 in St. Anthony Park, he said.
Again, many residents seemed unconvinced. Several argued that completing the existing wall is necessary to justify the expense of erecting it in the first place.
Another highway enhance-ment that Roy discussed is vegetation and landscaping. He said such additions would have no effect on noise levels, but MnDOT does have some money available for that use.
St. Anthony Park resident Alice Duggan urged the department to consider adding vegetation wherever it’s feasible.
“It might not make things quieter,” she said, “but at least it would let drivers know that this is a neighborhood, that people live here. Maybe they would slow down a little.”
The March 12 meeting addressed only that portion of 280 bordering St. Anthony Park. MnDOT has had separate discussions with Lauderdale, and construction of a sound wall north of Larpenteur is scheduled to begin in July.